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Re: [TF-A] [Hafnium] Debugging page table creation in Hafnium

by Madhukar Pappireddy

Hi Raghu and Andrew, Thanks for the inputs. I have added the mm_vm_dump() call to the mm_init() function but nothing was dumped to uart log. I guess I am missing something trivial. It looks like mm_root_table_count() returns 0. Any suggestions? diff --git a/src/mm.c b/src/mm.c index 2e352e9..7c56a09 100644 --- a/src/mm.c +++ b/src/mm.c @@ -1041,5 +1041,7 @@ bool mm_init(struct mpool *ppool) mm_identity_map(stage1_locked, layout_data_begin(), layout_data_end(), MM_MODE_R | MM_MODE_W, ppool); + mm_vm_dump(&ptable); + return arch_mm_init(ptable.root); } Thanks, Madhukar -----Original Message----- From: Hafnium <hafnium-bounces(a)lists.trustedfirmware.org> On Behalf Of Andrew Walbran via Hafnium Sent: Friday, July 17, 2020 6:10 AM To: Raghu K <raghu.ncstate(a)icloud.com> Cc: hafnium(a)lists.trustedfirmware.org Subject: Re: [Hafnium] Debugging page table creation in Hafnium Yep, mm_vm_dump sounds like what you're looking for. You can add a call where you like and it will go to the log UART. On Thu, 16 Jul 2020 at 19:14, Raghu K via Hafnium < hafnium(a)lists.trustedfirmware.org> wrote: > Quick search indicates mm_vm_dump() and the functions it calls in > src/mm.c should do what you want. i've not tried it or don't know the > format, but this may be what you are looking for. > > -Raghu > > On 7/16/20 11:03 AM, Madhukar Pappireddy via Hafnium wrote: > > Hi, > > > > I was wondering if there is support in Hafnium to dump page tables > > to a > log file. I am new to the Hafnium project and would appreciate any help. > Below is an example from TF-A which provides such provision. > > > > ......<snip> > > VERBOSE: Translation tables state: > > VERBOSE: Xlat regime: EL3 > > VERBOSE: Max allowed PA: 0xfffffffff > > VERBOSE: Max allowed VA: 0xfffffffff > > VERBOSE: Max mapped PA: 0x2f1fffff > > VERBOSE: Max mapped VA: 0x2f1fffff > > VERBOSE: Initial lookup level: 1 > > VERBOSE: Entries @initial lookup level: 64 > > VERBOSE: Used 3 sub-tables out of 5 (spare: 2) > > [LV1] VA:0x0 size:0x40000000 > > [LV2] VA:0x0 size:0x200000 > > [LV3] VA:0x0 PA:0x0 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x1000 PA:0x1000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x2000 PA:0x2000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x3000 PA:0x3000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x4000 PA:0x4000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x5000 PA:0x5000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x6000 PA:0x6000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x7000 PA:0x7000 size:0x1000 MEM-RO-EXEC-S > > [LV3] VA:0x8000 PA:0x8000 size:0x1000 MEM-RO-XN-S > > [LV3] VA:0x9000 PA:0x9000 size:0x1000 MEM-RO-XN-S > > [LV3] VA:0xa000 PA:0xa000 size:0x1000 MEM-RO-XN-S > > [LV3] VA:0xb000 size:0x1000 > > [LV3] (500 invalid descriptors omitted) > > [LV2] VA:0x200000 size:0x200000 > > [LV2] (30 invalid descriptors omitted) > > [LV2] VA:0x4000000 size:0x200000 ..... <snip> > > > > Thanks, > > Madhukar > > > > -- > Hafnium mailing list > Hafnium(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/hafnium >

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Re: [TF-A] Pointer Authentication keys

by Soby Mathew

Hi Varun, AIU, Usually 2 keys are used to protect 2 different software contexts for enforcing the security boundary between them. This is the case for kernel and userspace. In TF-A, every BL image is allowed to choose the IA key to use, hence every BL image can have a separate IA key. Each BL image is executing within a single security domain and hence there is less use create a boundary within the BL image by using the 2nd key registers. The Compiler by default selects either IA or IB instruction key register to use by default. It cannot automatically make use of both key registers and it doesn't support the use of DA or DB yet I think. There are some function attributes which allow to use a different key at a function level, but the functions need to be marked out manually. But the requirement for creating the sub-domain within a BL image by specifying a different key for certain functions has not yet been seen AFAIK. Best Regards Soby Mathew From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Varun Wadekar via TF-A Sent: 13 July 2020 22:20 To: tf-a(a)lists.trustedfirmware.org Cc: Kalyani Chidambaram Vaidyanathan <kalyanic(a)nvidia.com> Subject: [TF-A] Pointer Authentication keys Hi, >From the initial read of the Arm ARM, there are multiple keys (instruction, data) provided for authenticating pointers. But the current implementation only writes IA key [1]. I would like to understand the thought process behind programming only one key here. AFAIU, we should enable all keys - IA, IB, DA, DB. -Varun [1] https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/…

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Re: [TF-A] Announcing some changes around the code review label in Gerrit

by Joanna Farley

Hi Julius, Sandrine is away on vacation so I thought I would follow up as we had a chat in one of our team meetings about the point below. > On 07/07/2020, 23:05, "TF-A on behalf of Julius Werner via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: >> IOW, you're fine with both options but you'd prefer to have different >> people setting MR+1 and COR+1 (or CR+1 in the special cases mentioned >> above), right? Just want to double-check I understood your position. >Right. So when we had +1/+2 CR before these changes we endeavoured to ensure that these were done by different people and if a maintainer gave a +1 they resisted also giving a +2 as we recognise having multiple eyes is always advantageous. So the general feeling was that this should be the recommended best practice. However, the feeling was also that this specific recommendation should not be strictly enforced by gerrit checking as on occasions it is possible to give both on simple patches and maintainers and code owners in this case can be trusted to make the correct choice. The enforcing of them in Gerrit should be viewed as an aid to try and avoid mistakes rather than strict control for as you say we don't expect people to intentionally break the rules. Perhaps a warning in this case can be made to remind folks what's best practice here. For now though as mentioned as we practice the new rules and recommendations we will use an honour system rather than strict enforcement along with updating the documented rules and recomendations. Thanks Joanna

5 years, 5 months

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Re: [TF-A] Deadlock in SGI RAS handling

by Soby Mathew

Hi Raghu, The Exception Handling framework (EHF) was designed to provide prioritization between the EL3 interrupts and EA although EA will always have highest priority since it cannot be blocked. In the case you describe, the driver in EL3 which is handling the RAS errors would need to ensure serialization of the events delivered to the S-EL0 payload somehow. This could be either via holding the event in a queue in EL3 till EL0 is done with processing the first event or the EL0 payload is capable of re-entry and can manage a queue internally. In case of MM, I suppose re-entry is not an option and hence a holding queue in EL3 driver needs to be implemented. The current implementation in sgi_ras.c doesn't do this currently as this was a PoC to showcase the RAS flow. Best Regards Soby Mathew > -----Original Message----- > From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Raghu K > via TF-A > Sent: 13 July 2020 22:28 > To: tf-a(a)lists.trustedfirmware.org > Subject: [TF-A] Deadlock in SGI RAS handling > > Hi All, > > I was going through some code in sgi_ras.c and was wondering if the > situation mentioned below could cause a deadlock or if i'm missing > something. It seems like it is possible to deadlock if we enter MM in S- > EL0(say through an MM_COMMUNICATE SMC or perhaps an initial RAS > interrupt) followed by a SYNC EA or ASYNC EA on the same core. sgi_ras.c > seems like it registers the same handler for both interrupts and aborts. > While interrupts can be blocked/masked, SYNC EA's cannot be blocked(not > that i know of), and i don't see SErrors being blocked on the path to the EA > handler and entry to MM. If this situation does occur, it seems like we could > deadlock when the EA attempts to enter MM again in the interrupt handler. > Is there something that would prevent this situation from happening? > > > Thanks > Raghu > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 5 months

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Deadlock in SGI RAS handling

by Raghu K

Hi All, I was going through some code in sgi_ras.c and was wondering if the situation mentioned below could cause a deadlock or if i'm missing something. It seems like it is possible to deadlock if we enter MM in S-EL0(say through an MM_COMMUNICATE SMC or perhaps an initial RAS interrupt) followed by a SYNC EA or ASYNC EA on the same core. sgi_ras.c seems like it registers the same handler for both interrupts and aborts. While interrupts can be blocked/masked, SYNC EA's cannot be blocked(not that i know of), and i don't see SErrors being blocked on the path to the EA handler and entry to MM. If this situation does occur, it seems like we could deadlock when the EA attempts to enter MM again in the interrupt handler. Is there something that would prevent this situation from happening? Thanks Raghu

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Pointer Authentication keys

by Varun Wadekar

Hi, >From the initial read of the Arm ARM, there are multiple keys (instruction, data) provided for authenticating pointers. But the current implementation only writes IA key [1]. I would like to understand the thought process behind programming only one key here. AFAIU, we should enable all keys - IA, IB, DA, DB. -Varun [1] https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/…

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TF-A Tech Forum Agenda @ Thr 16th July 2020 16:00-1700 BST

by Joanna Farley

Hi All, The next TF-A Tech Forum is scheduled for Thu 16th July 2020 16:00 – 17:00 (BST). A reoccurring meeting invite has been sent out to the subscribers of this TF-A mailing list. If you don’t have this please let me know. Agenda: * Secure EL2 SPM (Secure Partition Manager) Hafnium-based * In this TF-A Tech Forum session we present the status and open roadmap for the Secure Partition Manager firmware development. The TF-A SPM is the reference open source implementation for the PSA FF-A (Platform Security Architecture Firmware Framework for A-class) specification in the Secure world. It leverages the Armv8.4-Secure EL2 extension bringing virtualization technology in the Secure world (S-EL2 exception level). The development derives originally from the Google Hafnium project, which has been recently transitioned to https://www.trustedfirmware.org/ under the BSD 3-Clause license. * Optional TF-A Mailing List Topic Discussions If TF-A contributors have anything they wish to present at any future TF-A tech forum please contact me to have that scheduled. Previous sessions, both recording and presentation material can be found on the trustedfirmware.org TF-A Technical meeting webpage: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/ A scheduling tracking page is also available to help track sessions suggested and being prepared: https://developer.trustedfirmware.org/w/tf_a/tf-a-tech-forum-scheduling/ Final decisions on what will be presented will be shared a few days before the next meeting and shared on the TF-A mailing list. Thanks Joanna

5 years, 5 months

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New Defects reported by Coverity Scan for ARM-software/arm-trusted-firmware

by scan-admin＠coverity.com

Hi, Please find the latest report on new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan. 4 new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan. New defect(s) Reported-by: Coverity Scan Showing 4 of 4 defect(s) ** CID 360537: Insecure data handling (TAINTED_SCALAR) ________________________________________________________________________________________________________ *** CID 360537: Insecure data handling (TAINTED_SCALAR) /plat/qemu/common/qemu_bl2_setup.c: 72 in update_dt() 66 67 if (dt_add_psci_cpu_enable_methods(fdt)) { 68 ERROR("Failed to add PSCI cpu enable methods in Device Tree\n"); 69 return; 70 } 71 >>> CID 360537: Insecure data handling (TAINTED_SCALAR) >>> Passing tainted variable "fdt->size_dt_struct" to a tainted sink. 72 ret = fdt_pack(fdt); 73 if (ret < 0) 74 ERROR("Failed to pack Device Tree at %p: error %d\n", fdt, ret); 75 } 76 77 void bl2_platform_setup(void) ** CID 360536: (TAINTED_SCALAR) ________________________________________________________________________________________________________ *** CID 360536: (TAINTED_SCALAR) /plat/rpi/rpi4/rpi4_bl31_setup.c: 249 in rpi4_prepare_dtb() 243 gic_int_prop[2] = cpu_to_fdt32(0x0f04); // all cores, level high 244 fdt_setprop(dtb, offs, "interrupts", gic_int_prop, 12); 245 246 offs = fdt_path_offset(dtb, "/chosen"); 247 fdt_setprop_string(dtb, offs, "stdout-path", "serial0"); 248 >>> CID 360536: (TAINTED_SCALAR) >>> Passing tainted variable "dtb->size_dt_struct" to a tainted sink. 249 ret = fdt_pack(dtb); 250 if (ret < 0) 251 ERROR("Failed to pack Device Tree at %p: error %d\n", dtb, ret); 252 253 clean_dcache_range((uintptr_t)dtb, dtb_size(dtb)); 254 INFO("Changed device tree to advertise PSCI.\n"); /plat/rpi/rpi4/rpi4_bl31_setup.c: 220 in rpi4_prepare_dtb() 214 int ret, offs; 215 216 /* Return if no device tree is detected */ 217 if (fdt_check_header(dtb) != 0) 218 return; 219 >>> CID 360536: (TAINTED_SCALAR) >>> Passing tainted variable "dtb->totalsize" to a tainted sink. 220 ret = fdt_open_into(dtb, dtb, 0x100000); 221 if (ret < 0) { 222 ERROR("Invalid Device Tree at %p: error %d\n", dtb, ret); 223 return; 224 } 225 /plat/rpi/rpi4/rpi4_bl31_setup.c: 249 in rpi4_prepare_dtb() 243 gic_int_prop[2] = cpu_to_fdt32(0x0f04); // all cores, level high 244 fdt_setprop(dtb, offs, "interrupts", gic_int_prop, 12); 245 246 offs = fdt_path_offset(dtb, "/chosen"); 247 fdt_setprop_string(dtb, offs, "stdout-path", "serial0"); 248 >>> CID 360536: (TAINTED_SCALAR) >>> Passing tainted variable "dtb->size_dt_struct" to a tainted sink. 249 ret = fdt_pack(dtb); 250 if (ret < 0) 251 ERROR("Failed to pack Device Tree at %p: error %d\n", dtb, ret); 252 253 clean_dcache_range((uintptr_t)dtb, dtb_size(dtb)); 254 INFO("Changed device tree to advertise PSCI.\n"); /plat/rpi/rpi4/rpi4_bl31_setup.c: 249 in rpi4_prepare_dtb() 243 gic_int_prop[2] = cpu_to_fdt32(0x0f04); // all cores, level high 244 fdt_setprop(dtb, offs, "interrupts", gic_int_prop, 12); 245 246 offs = fdt_path_offset(dtb, "/chosen"); 247 fdt_setprop_string(dtb, offs, "stdout-path", "serial0"); 248 >>> CID 360536: (TAINTED_SCALAR) >>> Passing tainted variable "dtb->size_dt_struct" to a tainted sink. 249 ret = fdt_pack(dtb); 250 if (ret < 0) 251 ERROR("Failed to pack Device Tree at %p: error %d\n", dtb, ret); 252 253 clean_dcache_range((uintptr_t)dtb, dtb_size(dtb)); 254 INFO("Changed device tree to advertise PSCI.\n"); /plat/rpi/rpi4/rpi4_bl31_setup.c: 249 in rpi4_prepare_dtb() 243 gic_int_prop[2] = cpu_to_fdt32(0x0f04); // all cores, level high 244 fdt_setprop(dtb, offs, "interrupts", gic_int_prop, 12); 245 246 offs = fdt_path_offset(dtb, "/chosen"); 247 fdt_setprop_string(dtb, offs, "stdout-path", "serial0"); 248 >>> CID 360536: (TAINTED_SCALAR) >>> Passing tainted variable "dtb->size_dt_struct" to a tainted sink. 249 ret = fdt_pack(dtb); 250 if (ret < 0) 251 ERROR("Failed to pack Device Tree at %p: error %d\n", dtb, ret); 252 253 clean_dcache_range((uintptr_t)dtb, dtb_size(dtb)); 254 INFO("Changed device tree to advertise PSCI.\n"); /plat/rpi/rpi4/rpi4_bl31_setup.c: 220 in rpi4_prepare_dtb() 214 int ret, offs; 215 216 /* Return if no device tree is detected */ 217 if (fdt_check_header(dtb) != 0) 218 return; 219 >>> CID 360536: (TAINTED_SCALAR) >>> Passing tainted variable "dtb->size_dt_strings" to a tainted sink. 220 ret = fdt_open_into(dtb, dtb, 0x100000); 221 if (ret < 0) { 222 ERROR("Invalid Device Tree at %p: error %d\n", dtb, ret); 223 return; 224 } 225 ** CID 360535: Insecure data handling (TAINTED_SCALAR) ________________________________________________________________________________________________________ *** CID 360535: Insecure data handling (TAINTED_SCALAR) /plat/renesas/rcar/bl2_plat_setup.c: 1005 in bl2_el3_early_platform_setup() 999 bl2_lossy_setting(1, LOSSY_ST_ADDR1, LOSSY_END_ADDR1, 1000 LOSSY_FMT1, LOSSY_ENA_DIS1, fcnlnode); 1001 bl2_lossy_setting(2, LOSSY_ST_ADDR2, LOSSY_END_ADDR2, 1002 LOSSY_FMT2, LOSSY_ENA_DIS2, fcnlnode); 1003 #endif 1004 >>> CID 360535: Insecure data handling (TAINTED_SCALAR) >>> Passing tainted variable "fdt->size_dt_struct" to a tainted sink. 1005 fdt_pack(fdt); 1006 NOTICE("BL2: FDT at %p\n", fdt); 1007 1008 if (boot_dev == MODEMR_BOOT_DEV_EMMC_25X1 || 1009 boot_dev == MODEMR_BOOT_DEV_EMMC_50X8) 1010 rcar_io_emmc_setup(); ** CID 346762: (TAINTED_SCALAR) ________________________________________________________________________________________________________ *** CID 346762: (TAINTED_SCALAR) /lib/libfdt/fdt_empty_tree.c: 37 in fdt_create_empty_tree() 31 return err; 32 33 err = fdt_finish(buf); 34 if (err) 35 return err; 36 >>> CID 346762: (TAINTED_SCALAR) >>> Passing tainted variable "buf->size_dt_struct" to a tainted sink. 37 return fdt_open_into(buf, buf, bufsize); /lib/libfdt/fdt_empty_tree.c: 33 in fdt_create_empty_tree() 27 return err; 28 29 err = fdt_end_node(buf); 30 if (err) 31 return err; 32 >>> CID 346762: (TAINTED_SCALAR) >>> Passing tainted variable "buf->size_dt_strings" to a tainted sink. 33 err = fdt_finish(buf); 34 if (err) 35 return err; 36 37 return fdt_open_into(buf, buf, bufsize); /lib/libfdt/fdt_empty_tree.c: 37 in fdt_create_empty_tree() 31 return err; 32 33 err = fdt_finish(buf); 34 if (err) 35 return err; 36 >>> CID 346762: (TAINTED_SCALAR) >>> Passing tainted variable "buf->totalsize" to a tainted sink. 37 return fdt_open_into(buf, buf, bufsize); /lib/libfdt/fdt_empty_tree.c: 37 in fdt_create_empty_tree() 31 return err; 32 33 err = fdt_finish(buf); 34 if (err) 35 return err; 36 >>> CID 346762: (TAINTED_SCALAR) >>> Passing tainted variable "buf->size_dt_strings" to a tainted sink. 37 return fdt_open_into(buf, buf, bufsize); ________________________________________________________________________________________________________ To view the defects in Coverity Scan visit, https://u2389337.ct.sendgrid.net/ls/click?upn=nJaKvJSIH-2FPAfmty-2BK5tYpPkl…

5 years, 5 months

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Re: [TF-A] Announcing some changes around the code review label in Gerrit

by Joanna Farley

+1 for re-introduction of 'Code-Review' label in addition to 'Code-Owner-Review' label. I would like to see the enforcement of authors of patches not being allowed to self review eventually for all labels. Hopefully we can enable maintainers who are not the author of deadlocked patches to allow the setting of all required +1's to labels is situations where this is necessary for admin purposes after due consideration. I agree though while this process is settling down an honour system is appropriate. Cheers Joanna On 01/07/2020, 08:56, "TF-A on behalf of Sandrine Bailleux via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Hi Julius, On 7/1/20 2:13 AM, Julius Werner wrote: > Hi Sandrine, > > Sounds like good changes in general! I'm curious what the ACLs are for > Code-Owner-Review? Is it tied to docs/about/maintainers.rst or just > based on the honor system? (I notice that I seem to be able to give a > +1 for code I'm not owning, but maybe that's because I am a > maintainer?) Right now, the ACLs are not tied to docs/about/maintainers.rst (any registered user could vote on this label) and it is just based on the honor system. However, I'd like this to be enforced in the future, we just haven't had the time to put the right tooling in place for that. Also we did not want to spend time on developing such scripts before we tried out these process changes in practice. If they proved too heavy or inconvenient, part of this work would have gone to waste. BTW, any help for the tooling is welcome! If you've got plugin configuration files or scripts we could reuse (with an appropriate license) or even tips on how to best set this up, please feel free to share these. > Also, are code owners allowed to +1 themselves (I think > we said we didn't want maintainers to do that, but for code owners I > could see how we might want to allow it since there are usually not > that many)? What do we do when someone uploads the first patch for a > new platform, do they just COR+1 themselves (since there is no code > owner yet)? That is indeed a grey area. As you say, many modules have a single code owner and we need to agree on how we would like such code reviews to be conducted. Thanks for starting this discussion! One option as you say would be to allow code owners to self-review their patches but I am not convinced we would gain anything out of this. It sounds like a tick-box exercise to me, an admin overhead just to get the patch through the system and I would like to avoid that as much as possible. It is likely that a patch submitter has already self-reviewed his code before posting a patch anyway. The alternative we've been discussing in the team is to call out another reviewer in these situations. I think that there is still value in having a second fresh pair of eyes on a patch. Even if the reviewer has no particular expertise on this specific module, they can still catch potential logic problems or structural issues in the code. The latter would be my preference. What do others think? > I think it might still be useful to retain the existing Code-Review as > a +1/-1 label next to the two new ones, just to allow other interested > parties to record their opinion (without it having any enforcing > effect on the merge). In other Gerrit instances I have used people > often like to give CR+1 as a "I'm not the one who needs to approve > this but I have looked at it and think it's fine" or a CR-1 as a "I > can't stop you from doing this but I still want to be clear that I > don't think it's a good idea". It allows people outside the official > approval process a clearer way to participate and can aid the official > approvers in their decisions (e.g. when I am reviewing a patch as a > maintainer that already has a CR-1 from someone else I know to pay > extra attention to their concerns, and it's more visible than just > some random comment further up in the list). What do you think? That's a very good idea, thanks! It also aligns with Javier's concerns, which sound perfectly valid to me. I think your proposal of having 3 distinct labels is better than having code owners and non-code owners voting on the same generic 'Code-Review' label, which is what Javier was suggesting. It clarifies further the intent of each label and as you say allows us to configure different rules for each (i.e. make the generic 'Code-Review' label informative/optional, while making the 'Code-Owner-Review' label mandatory for patch submission). I am gonna wait for others' opinions on this before changing the configuration in Gerrit again. I see Raghu agrees with this approach. If nobody disagrees by the end of the week, I'll do these changes on Monday. In the meantime, as discussed above, any registered user can vote on the new 'Code-Owner-Review' label so let's continue to use that for the rest of this week. Regards, Sandrine -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

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Re: [TF-A] Announcing some changes around the code review label in Gerrit

by Varun Wadekar

Hello Sandrine, IMO, the code review process has now evolved from the previous version. I am not too clear on the final outcome. Does it make sense to add a "lifecycle of a review" section to the initial proposal? -Varun -----Original Message----- From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Sandrine Bailleux via TF-A Sent: Monday, July 6, 2020 1:53 AM To: Julius Werner <jwerner(a)chromium.org> Cc: tf-a <tf-a(a)lists.trustedfirmware.org> Subject: Re: [TF-A] Announcing some changes around the code review label in Gerrit External email: Use caution opening links or attachments Hi Julius and all, As agreed and announced last week, I've now reintroduced the Code-Review label in addition to the Code-Owner-Review and Maintainer-Review ones. The Code-Review label is purely informational and won't influence whether a patch is submittable in Gerrit. Anyone should be able to vote on this label, if you face any issue please let me know. On 7/1/20 11:12 PM, Julius Werner wrote: >> BTW, any help for the tooling is welcome! If you've got plugin >> configuration files or scripts we could reuse (with an appropriate >> license) or even tips on how to best set this up, please feel free to >> share these. > > The Chromium Gerrit has an owners-enforcement system but I'm not > familiar with how exactly they set it up. I think they're using this > plugin > https://gerrit.googlesource.com/plugins/find-owners/+/refs/heads/maste > r and this is where it's integrated into Gerrit submission rules: > https://chromium.googlesource.com/chromiumos/+/refs/meta/config/rules. > pl . It works by having a file called OWNERS in certain directories > which sets the owners for the subtree below it, so we would have to > rewrite the current code owner list in that format if we wanted to use > it. This "find-owners" plugin sounds promising! Thanks for the pointers. I notice the "reviewers" plugin [1] is installed on review.tf.org but it does not sound as configurable as "find-owners". Rewriting the current code owners list to use the OWNERS format does not sound like a big task to me (just a dull one... could be scripted, though) so this approach definitely sounds worth investigating to me. [1] https://review.trustedfirmware.org/plugins/reviewers/Documentation/index.ht… > There also seems to be this completely separate plugin that claims to > do roughly the same thing, I have no idea where the difference is > between the two: > https://gerrit.googlesource.com/plugins/owners/+/refs/heads/master I notice the "find-owners" plugin documentation mentions that "this plugin works with Gerrit projects that use Android or Chromium compatible OWNERS files" so maybe they started off from the generic "owners" plugin and customized it for Android/Chromium's needs? Just a guess. Anyway, worth a look as well, thanks! [2] https://gerrit.googlesource.com/plugins/find-owners/+/refs/heads/master/src… >> One option as you say would be to allow code owners to self-review their >> patches but I am not convinced we would gain anything out of this. It >> sounds like a tick-box exercise to me, an admin overhead just to get the >> patch through the system and I would like to avoid that as much as >> possible. It is likely that a patch submitter has already self-reviewed >> his code before posting a patch anyway. >> >> The alternative we've been discussing in the team is to call out another >> reviewer in these situations. I think that there is still value in >> having a second fresh pair of eyes on a patch. Even if the reviewer has >> no particular expertise on this specific module, they can still catch >> potential logic problems or structural issues in the code. > > I definitely did not mean to suggest that these patches should not be > reviewed at all -- I was just talking about the Code-Owner-Review > label. There would still be a maintainer review, of course, and it > seems like a good idea to get additional reviews from other people > too. They just couldn't set the COR+1 bit once we start ACLing it. Right, I see (and agree with you). > Basically, each of these bits have their own purpose, and I would see > the purpose of the COR+1 bit to be that the person most familiar with > that particular piece of code has made sure that it fits in and > doesn't cause unexpected problems with certain quirky configurations > or something like that. That's important when, say, I make a generic > refactoring that touches a platform I'm unfamiliar with, but if the > code owner adds to their own platform that's probably already a given > and they are likely still the best person to judge that, even for > their own code. Yes, that makes sense to me. > That all code gets reviewed by people other than the author I would > see as a somewhat orthogonal concern that should be checked > independently. So maybe the rule could be that if the code owner sets > COR+1 for themselves, there needs to be at least one Code-Review+1 (if > we reintroduce that label) from another person (who is also not the > one setting Maintainer-Review+1) to make sure the minimum amount of > reviews stays the same. Or maybe these should all be completely > independent checks so every patch needs a Code-Owner-Review+1 (can be > from the author), a Maintainer-Review+1 (not from the author) and at > least two Code-Review+1 from people other than the author -- with the > normal expectation that when a maintainer or code owner reviews a > patch, they would also set Code-Review+1 (as a general sign that they > reviewed the patch) in addition to their special meaning flag. I still don't see the benefit of code owners setting COR+1 for themselves. I would think that a patch owner already reviews his own patch before posting it for review so a self COR+1 is just reinstating the obvious in my eyes. Your first suggestion (i.e. having at least one CR+1 from another person when a patch author cannot find another code owner to review their patches) sounds aligned with what I proposed earlier. Your second suggestion sounds a bit too heavy to me. The fact that people would have to replay their vote on several labels sounds like an admin overhead to me. I guess this would simplify the ACL configuration but I would prefer to avoid this if we can. So I suggest the following. We could have 2 ways to get a patch approved. 1) For patches that have multiple code owners: * COR+1 (not from patch owner) * MR+1 (not from patch owner, not from the person setting COR+1) 2) For patches that a have single code owner: * CR+1 (not from patch owner) * MR+1 (not from patch owner, not from the person setting CR+1) In 2), I like your suggestion of mandating 2 CR+1 but I fear this might be difficult to achieve in practice (simply because we might not have enough reviewers for this). Note that in some cases, we would need to mix both policies. If a patch modifies several modules, some of them having multiple code owners and others having a single code owner, we would apply one or the other policy for each module. How does that sound? Also, 1) assumes we always want different individuals doing the code-owner review and the maintainer review. I personally don't feel strongly about this split and I would be fine with the same person doing both types of review, as they are typically looking at different criteria. What do others think? Regards, Sandrine -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 5 months

2
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Re: [TF-A] Erroneous speculative AT workaround

by Soby Mathew

Thanks Andrew for raising the issue and Marc and Raghu for your inputs. The effect of stage 2 when Stage 1 is disabled is something that was overlooked in the workaround implementation. After some discussions this is what we currently understand regarding the problem. 1. EL3 does not modify the EL2 stage 1 translations and hence any speculative execution of AT execution in EL3 and resulting PTW and TLB caching should not be a problem as we always return to the same context in EL2. TF-A in EL3 need not worry about this. Also, we expect that future CPUs having v8.4 extensions for S-EL2 will have already corrected this errata. 2. Whenever the EL1/0 Stage 1 translations are switched in EL3 as part of switching the worlds, it should take Stage 2 into account. Hence disabling the Stage 1 MMU is not effective, as Marc pointed out, because speculative PTW can still take place using Stage 2 identity mapping. After discussion with James, we also realized that flipping the SCR_EL3.NS bit could take Stage 2 out of context (Stage 2 is not valid in secure world) leaving Stage 1 pointing to invalid translations. As discussed in previous emails, on Entry to EL3, if TCR_EL1.EPDx = 1 and SCTLR_EL3.M = 1, any speculative AT PTWs for EL1 context can be prevented (including Stage 2). So the fix as we currently understand would involve the following sequence : a. On Entry to EL3, save the incoming SCTLR_EL1.M and TCR_EL1.EPDx bits and set them (ensure TCR_EL1.EPDx =1 prior to SCTLR_EL1.M =1 using isb()) b. Prior to Exit from EL3, after the target context is restored, restore the SCTLR_EL1.M and TCR_EL1.EPDx bits. The above sequence now means that any use of AT instruction targeted at lower EL from EL3 that require PTW will fault. So prior to use of AT, ensure the PTW are re-enabled and disabled back again after the AT instructions. If the above sequence is agreed upon to resolve the errata, then we can work on a patch for the same. I suspect current el1 register save and restore sequence in TF-A is a bit unwieldy and we may need to analyze all the entry points to EL3 to ensure we cover everything. Best Regards Soby Mathew > -----Original Message----- > From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of Andrew > Scull via TF-A > Sent: 02 July 2020 09:20 > To: Raghu K <raghu.ncstate(a)icloud.com> > Cc: android-kvm(a)google.com; willdeacon(a)google.com; Marc Zyngier > <mzyngier(a)google.com>; tf-a(a)lists.trustedfirmware.org > Subject: Re: [TF-A] Erroneous speculative AT workaround > > On Wed, Jul 01, 2020 at 05:47:00PM -0700, Raghu K wrote: > > This is interesting. It appears that there is no way on entry to EL3 > > to guarantee that the out-of-context(el2 and el1) translation regimes > > are in a consistent state and on every entry into EL3, we have to > > conservatively assume that it is in an inconsistent state. This is > > because of the situation Andrew mentioned(interrupts to EL3 can occur at any > time). > > > > If this is the case, on EL3 entry: > > 1) For EL1, we will need to save SCTLR_EL1, set SCTLR_EL1.M = 1,.EPDx > > = 0 > > This would still be racing against any potential speculative execution of an AT > instruction upon the switch to EL3, IIUC. The window would be much smaller > but not entirely eliminated. > > For KVM, this would be enough as KVM will have already applied this > workaround (with Marc's corrections) whenever it is going to enter an > inconsistent state. However, other EL2 software may choose to handle the > errata differently, possibly going to the lengths of ensuring that no AT > instruction is ever mapped executable. > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 5 months

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Re: [TF-A] Erroneous speculative AT workaround

by Raghu K

5 years, 6 months

1
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Re: [TF-A] Erroneous speculative AT workaround

by Raghu K

5 years, 6 months

1
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Re: [TF-A] Erroneous speculative AT workaround

by Raghu K

This is interesting. It appears that there is no way on entry to EL3 to guarantee that the out-of-context(el2 and el1) translation regimes are in a consistent state and on every entry into EL3, we have to conservatively assume that it is in an inconsistent state. This is because of the situation Andrew mentioned(interrupts to EL3 can occur at any time). If this is the case, on EL3 entry: 1) For EL1, we will need to save SCTLR_EL1, set SCTLR_EL1.M = 1,.EPDx = 0 2) Set whatever bits we need to for EL2 and S2 translations to not succeed(What are these?) 3) DSB, to ensure no speculative AT can be issued until completion of DSB, so any AT that occurs will not fill the TLB with bad translations. On exit(right before ERET), we need to restore the registers saved on entry, and have the ERET followed by a DSB so that there can be no speculative execution of AT instructions. Thanks Raghu On 7/1/20 5:54 AM, Marc Zyngier via TF-A wrote: > Hi Manish, > > On Wed, 1 Jul 2020 at 13:14, Manish Badarkhe <Manish.Badarkhe(a)arm.com> wrote: >> Hi Andrew, >> >> As per current implementation, in “el1_sysregs_context_restore” routine do below things: >> >> 1. TCR_EL1.EPD0 = 1 >> 2. TCR_EL1.EPD1 = 1 >> 3. SCTR_EL1.M = 0 >> 4. Isb >> Code snippet: >> mrs x9, tcr_el1 >> orr x9, x9, #TCR_EPD0_BIT >> orr x9, x9, #TCR_EPD1_BIT >> msr tcr_el1, x9 >> mrs x9, sctlr_el1 >> bic x9, x9, #SCTLR_M_BIT >> msr sctlr_el1, x9 >> isb >> This is to avoid PTW through while updating system registers at step 5 > Unfortunately, this doesn't prevent anything. > > If SCTLR_EL1.M is clear, TCR_EL1.EPDx don't mean much (S1 MMU is > disabled, no S1 page table walk), and you can still have S2 PTWs > (using an idmap for S1) and creating TLB corruption if these entry > alias with any S1 mapping that exists at EL1. > > Which is why KVM does *set* SCTLR_EL1.M, which prevents the use of a > 1:1 mapping at S1, and at which point the TCR_EL1.EPDx bits are > actually useful in preventing a PTW. > >> 5. Restore all system registers for El1 except SCTLR_EL1 and TCR_EL1 >> 6. isb() >> 7. restore SCTLR_EL1 and TCR_EL1 >> Code Snippet: >> ldr x9, [x0, #CTX_SCTLR_EL1] -> saved value from "el2_sysregs_context_save" >> msr sctlr_el1, x9 >> ldr x9, [x0, #CTX_TCR_EL1] >> msr tcr_el1, x9 >> >> As per above steps. SCTLR_EL1 get restored back with actual settings at step 7. >> Similar flow is present for “el2_sysregs_context_restore” to restore SCTLR_EL1 register. >> >> In conclusion, this routine temporarily clear M bit of SCTLR_EL1 to avoid speculation but restored it back >> to its original setting while leaving back to its caller. Please let us know whether this align with KVM >> workaround for speculative AT erratum. > It doesn't, unfortunately. I believe this code actively creates > problems on a system that is affected by speculative AT execution. > > I don't understand your rationale for touching SCTLR_EL2.M either if > you are not context-switching the EL2 S1 state: as far as I understand > no affected cores have S-EL2, so no switch should happen at this > stage. > > Thanks, > > M.

5 years, 6 months

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Re: [TF-A] Erroneous speculative AT workaround

by Manish Badarkhe

Hi Andrew, As per current implementation, in “el1_sysregs_context_restore” routine do below things: 1. TCR_EL1.EPD0 = 1 2. TCR_EL1.EPD1 = 1 3. SCTR_EL1.M = 0 4. Isb Code snippet: mrs x9, tcr_el1 orr x9, x9, #TCR_EPD0_BIT orr x9, x9, #TCR_EPD1_BIT msr tcr_el1, x9 mrs x9, sctlr_el1 bic x9, x9, #SCTLR_M_BIT msr sctlr_el1, x9 isb This is to avoid PTW through while updating system registers at step 5 5. Restore all system registers for El1 except SCTLR_EL1 and TCR_EL1 6. isb() 7. restore SCTLR_EL1 and TCR_EL1 Code Snippet: ldr x9, [x0, #CTX_SCTLR_EL1] -> saved value from "el2_sysregs_context_save" msr sctlr_el1, x9 ldr x9, [x0, #CTX_TCR_EL1] msr tcr_el1, x9 As per above steps. SCTLR_EL1 get restored back with actual settings at step 7. Similar flow is present for “el2_sysregs_context_restore” to restore SCTLR_EL1 register. In conclusion, this routine temporarily clear M bit of SCTLR_EL1 to avoid speculation but restored it back to its original setting while leaving back to its caller. Please let us know whether this align with KVM workaround for speculative AT erratum. Thanks Manish Badarkhe On 01/07/2020, 17:02, "TF-A on behalf of Joanna Farley via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Thanks Andrew for the notification. We will look into it and get back to this thread. Thanks Joanna On 01/07/2020, 10:16, "TF-A on behalf of Andrew Scull via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Whilst looking at the speculative AT workaround in KVM, I compared it against the workaround in TF-A and noticed an inconsistency whereby TF-A **breaks** KVM's workaround. In `el1_sysregs_context_restore`, the M bit of SCTRL_EL1 is cleared however Linux requires this to be set for its workaround to be correct. If an exception is taken to EL3 partway through a VM context switch, e.g. a secure interrupt, causing a switch to the secure world, TF-A will reintroduce the possibility of TLB corruption. The above explains how it is broken for Linux's chosen workaround however TF-A will also have to be compatible with whatever workaround the EL2 software is using. Starting this thread with the issue identified and we can add more details as needed. Thanks Andrew -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 6 months

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Re: [TF-A] Erroneous speculative AT workaround

by Manish Badarkhe

+Updated comment for SCTLR_EL2 register restoration. On 01/07/2020, 17:45, "TF-A on behalf of Manish Badarkhe via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Hi Andrew, As per current implementation, in “el1_sysregs_context_restore” routine do below things: 1. TCR_EL1.EPD0 = 1 2. TCR_EL1.EPD1 = 1 3. SCTR_EL1.M = 0 4. Isb Code snippet: mrs x9, tcr_el1 orr x9, x9, #TCR_EPD0_BIT orr x9, x9, #TCR_EPD1_BIT msr tcr_el1, x9 mrs x9, sctlr_el1 bic x9, x9, #SCTLR_M_BIT msr sctlr_el1, x9 isb This is to avoid PTW through while updating system registers at step 5 5. Restore all system registers for El1 except SCTLR_EL1 and TCR_EL1 6. isb() 7. restore SCTLR_EL1 and TCR_EL1 Code Snippet: ldr x9, [x0, #CTX_SCTLR_EL1] -> saved value from "el2_sysregs_context_save" msr sctlr_el1, x9 ldr x9, [x0, #CTX_TCR_EL1] msr tcr_el1, x9 As per above steps. SCTLR_EL1 get restored back with actual settings at step 7. Similar flow is present for “el2_sysregs_context_restore” to restore SCTLR_EL2 register. In conclusion, this routine temporarily clear M bit of SCTLR_EL1 to avoid speculation but restored it back to its original setting while leaving back to its caller. Please let us know whether this align with KVM workaround for speculative AT erratum. Thanks Manish Badarkhe On 01/07/2020, 17:02, "TF-A on behalf of Joanna Farley via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Thanks Andrew for the notification. We will look into it and get back to this thread. Thanks Joanna On 01/07/2020, 10:16, "TF-A on behalf of Andrew Scull via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Whilst looking at the speculative AT workaround in KVM, I compared it against the workaround in TF-A and noticed an inconsistency whereby TF-A **breaks** KVM's workaround. In `el1_sysregs_context_restore`, the M bit of SCTRL_EL1 is cleared however Linux requires this to be set for its workaround to be correct. If an exception is taken to EL3 partway through a VM context switch, e.g. a secure interrupt, causing a switch to the secure world, TF-A will reintroduce the possibility of TLB corruption. The above explains how it is broken for Linux's chosen workaround however TF-A will also have to be compatible with whatever workaround the EL2 software is using. Starting this thread with the issue identified and we can add more details as needed. Thanks Andrew -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 6 months

1
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Re: [TF-A] Erroneous speculative AT workaround

by Joanna Farley

Thanks Andrew for the notification. We will look into it and get back to this thread. Thanks Joanna On 01/07/2020, 10:16, "TF-A on behalf of Andrew Scull via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Whilst looking at the speculative AT workaround in KVM, I compared it against the workaround in TF-A and noticed an inconsistency whereby TF-A **breaks** KVM's workaround. In `el1_sysregs_context_restore`, the M bit of SCTRL_EL1 is cleared however Linux requires this to be set for its workaround to be correct. If an exception is taken to EL3 partway through a VM context switch, e.g. a secure interrupt, causing a switch to the secure world, TF-A will reintroduce the possibility of TLB corruption. The above explains how it is broken for Linux's chosen workaround however TF-A will also have to be compatible with whatever workaround the EL2 software is using. Starting this thread with the issue identified and we can add more details as needed. Thanks Andrew -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 6 months

1
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Erroneous speculative AT workaround

by Andrew Scull

Whilst looking at the speculative AT workaround in KVM, I compared it against the workaround in TF-A and noticed an inconsistency whereby TF-A **breaks** KVM's workaround. In `el1_sysregs_context_restore`, the M bit of SCTRL_EL1 is cleared however Linux requires this to be set for its workaround to be correct. If an exception is taken to EL3 partway through a VM context switch, e.g. a secure interrupt, causing a switch to the secure world, TF-A will reintroduce the possibility of TLB corruption. The above explains how it is broken for Linux's chosen workaround however TF-A will also have to be compatible with whatever workaround the EL2 software is using. Starting this thread with the issue identified and we can add more details as needed. Thanks Andrew

5 years, 6 months

1
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Re: [TF-A] Announcing some changes around the code review label in Gerrit

by Julius Werner

Hi Sandrine, Sounds like good changes in general! I'm curious what the ACLs are for Code-Owner-Review? Is it tied to docs/about/maintainers.rst or just based on the honor system? (I notice that I seem to be able to give a +1 for code I'm not owning, but maybe that's because I am a maintainer?) Also, are code owners allowed to +1 themselves (I think we said we didn't want maintainers to do that, but for code owners I could see how we might want to allow it since there are usually not that many)? What do we do when someone uploads the first patch for a new platform, do they just COR+1 themselves (since there is no code owner yet)? I think it might still be useful to retain the existing Code-Review as a +1/-1 label next to the two new ones, just to allow other interested parties to record their opinion (without it having any enforcing effect on the merge). In other Gerrit instances I have used people often like to give CR+1 as a "I'm not the one who needs to approve this but I have looked at it and think it's fine" or a CR-1 as a "I can't stop you from doing this but I still want to be clear that I don't think it's a good idea". It allows people outside the official approval process a clearer way to participate and can aid the official approvers in their decisions (e.g. when I am reviewing a patch as a maintainer that already has a CR-1 from someone else I know to pay extra attention to their concerns, and it's more visible than just some random comment further up in the list). What do you think? Best regards, Julius

5 years, 6 months

2
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Re: [TF-A] Announcing some changes around the code review label in Gerrit

by Javier Almansa Sobrino

Hi Sandrine, If my understanding is right, Code-Owner-Review is the equivalent to the old Code-Review+1 and therefore anyone can add a vote there, owner or not. If that is so, I think the current name might be misleading. Wouldn't it be better just "Code-Review", for instance? As an example, I am not code owner for Measure Boot, but sometimes I am requested to review the patches for it, so in that case it might lead to confusion if I give Code-Owner-Review score. What do you think? Best regards, Javier -----Original Message----- From: Sandrine Bailleux via TF-A <tf-a(a)lists.trustedfirmware.org<mailto:Sandrine%20Bailleux%20via%20TF-A%20%3ctf-a@lists.trustedfirmware.org%3e>> Reply-To: Sandrine Bailleux <sandrine.bailleux(a)arm.com<mailto:Sandrine%20Bailleux%20%3csandrine.bailleux@arm.com%3e>> To: tf-a <tf-a(a)lists.trustedfirmware.org<mailto:tf-a%20%3ctf-a@lists.trustedfirmware.org%3e>> Subject: [TF-A] Announcing some changes around the code review label in Gerrit Date: Tue, 30 Jun 2020 13:29:00 +0000 Hello all, If you recall, the tf.org Project Maintenance Process [1] advocates a code review model where both code owners and maintainers need to review and approve a patch before it gets merged. Until now, the way we would record this in Gerrit was a bit cumbersome and ambiguous. * Code-Review+1 was for code owners to approve a patch. * Code-Review+2 was for maintainers to approve a patch. The submission rules in Gerrit were such that a patch needed a Code-Review+2 to be merged. This meant that if a maintainer was first to take a look at a patch and approved it (Code-Review+2), Gerrit would allow the patch to be merged without any code owners review. To align better with the Project Maintenance Process, I've done some changes in our Gerrit configuration. You will notice that the Code-Review label is gone and has been replaced by 2 new labels: * Code-Owner-Review * Maintainer-Review Stating the obvious but code owners are expected to vote on the Code-Owner-Review label and maintainers on the Maintainer-Review. Note that maintainers might also be code owners for some modules. If they are doing a "code owner" type of review on a patch, they would vote on the Code-Owner-Review label in this case. Any doubt, please ask. I hope I didn't break anything but if you notice any permissions problems (things you used to be able to do and cannot do anymore, or vice versa!) please let me know. One annoying consequence of this change is that if you've got some patches in review right now and got some votes on the former 'Code-Review' label, these have been partially lost. The history of review comments in Gerrit will still show that somebody had voted Code-Review -1/+1 on your patch but this will no longer appear in the labels summary frame and won't count towards the approvals required to get the patch merged. I could not think of a way to avoid this issue... This should only be temporary, while we transition all in-flight patches to the new code review model. Roughly: * Existing "Code-Review -1/+1" votes will have to be replayed as "Code-Owner-Review -1/+1". * Existing "Code-Review -2/+2" votes will have to be replayed as "Maintainer-Review -1/+1". Sorry for the inconvenience. I hope, once we've gone through the transition period, these changes will make the code review process clearer to everybody. I will update the TF-A documentation to explain all of this in the coming future. Best regards, Sandrine [1] https://developer.trustedfirmware.org/w/collaboration/project-maintenance-p…

5 years, 6 months

1
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New TrustedFirmware.org security incident process is now live

by Dan Handley

Hi all The new TrustedFirmware.org security incident process is now live. This process is described here: https://developer.trustedfirmware.org/w/collaboration/security_center/repor… Initially the process will be used for the following projects: TF-A, TF-M, OP-TEE and Mbed TLS. The security documentation for each project will be updated soon to reflect this change. If you are part of an organization that believes it should receive security vulnerability information before it is made public then please ask your relevant colleagues to register as Trusted Stakeholders as described here: https://developer.trustedfirmware.org/w/collaboration/security_center/trust… Note we prefer individuals in each organization to coordinate their registration requests with each other and to provide us with an email alias managed by your organization instead of us managing a long list of individual addresses. Best regards Dan. (on behalf of the TrustedFirmware.org security team)

5 years, 6 months

1
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Announcing some changes around the code review label in Gerrit

by Sandrine Bailleux

Hello all, If you recall, the tf.org Project Maintenance Process [1] advocates a code review model where both code owners and maintainers need to review and approve a patch before it gets merged. Until now, the way we would record this in Gerrit was a bit cumbersome and ambiguous. * Code-Review+1 was for code owners to approve a patch. * Code-Review+2 was for maintainers to approve a patch. The submission rules in Gerrit were such that a patch needed a Code-Review+2 to be merged. This meant that if a maintainer was first to take a look at a patch and approved it (Code-Review+2), Gerrit would allow the patch to be merged without any code owners review. To align better with the Project Maintenance Process, I've done some changes in our Gerrit configuration. You will notice that the Code-Review label is gone and has been replaced by 2 new labels: * Code-Owner-Review * Maintainer-Review Stating the obvious but code owners are expected to vote on the Code-Owner-Review label and maintainers on the Maintainer-Review. Note that maintainers might also be code owners for some modules. If they are doing a "code owner" type of review on a patch, they would vote on the Code-Owner-Review label in this case. Any doubt, please ask. I hope I didn't break anything but if you notice any permissions problems (things you used to be able to do and cannot do anymore, or vice versa!) please let me know. One annoying consequence of this change is that if you've got some patches in review right now and got some votes on the former 'Code-Review' label, these have been partially lost. The history of review comments in Gerrit will still show that somebody had voted Code-Review -1/+1 on your patch but this will no longer appear in the labels summary frame and won't count towards the approvals required to get the patch merged. I could not think of a way to avoid this issue... This should only be temporary, while we transition all in-flight patches to the new code review model. Roughly: * Existing "Code-Review -1/+1" votes will have to be replayed as "Code-Owner-Review -1/+1". * Existing "Code-Review -2/+2" votes will have to be replayed as "Maintainer-Review -1/+1". Sorry for the inconvenience. I hope, once we've gone through the transition period, these changes will make the code review process clearer to everybody. I will update the TF-A documentation to explain all of this in the coming future. Best regards, Sandrine [1] https://developer.trustedfirmware.org/w/collaboration/project-maintenance-p…

5 years, 6 months

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New Defects reported by Coverity Scan for ARM-software/arm-trusted-firmware

by scan-admin＠coverity.com

Hi, Please find the latest report on new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan. 1 new defect(s) introduced to ARM-software/arm-trusted-firmware found with Coverity Scan. New defect(s) Reported-by: Coverity Scan Showing 1 of 1 defect(s) ** CID 360213: Null pointer dereferences (NULL_RETURNS) /plat/arm/common/arm_dyn_cfg.c: 96 in arm_bl1_set_mbedtls_heap() ________________________________________________________________________________________________________ *** CID 360213: Null pointer dereferences (NULL_RETURNS) /plat/arm/common/arm_dyn_cfg.c: 96 in arm_bl1_set_mbedtls_heap() 90 * In the latter case, if we still wanted to write in the DTB the heap 91 * information, we would need to call plat_get_mbedtls_heap to retrieve 92 * the default heap's address and size. 93 */ 94 95 tb_fw_config_info = FCONF_GET_PROPERTY(dyn_cfg, dtb, TB_FW_CONFIG_ID); >>> CID 360213: Null pointer dereferences (NULL_RETURNS) >>> Dereferencing "tb_fw_config_info", which is known to be "NULL". 96 tb_fw_cfg_dtb = tb_fw_config_info->config_addr; 97 98 if ((tb_fw_cfg_dtb != 0UL) && (mbedtls_heap_addr != NULL)) { 99 /* As libfdt use void *, we can't avoid this cast */ 100 void *dtb = (void *)tb_fw_cfg_dtb; 101 ________________________________________________________________________________________________________ To view the defects in Coverity Scan visit, https://u2389337.ct.sendgrid.net/ls/click?upn=nJaKvJSIH-2FPAfmty-2BK5tYpPkl…

5 years, 6 months

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TF-A Tech Forum Agenda @ Thr 2nd July 2020 16:00-1700 BST

by Joanna Farley

Hi All, The next TF-A Tech Forum is scheduled for Thu 2nd July 2020 16:00 – 17:00 (BST). A reoccurring meeting invite has been sent out to the subscribers of this TF-A mailing list. If you don’t have this please let me know. Agenda: * PSA Fuzz Testing - Presented by Gary Morrison * Originally developed for TF-M PSA API’s this is a different approach to Fuzz testing to that was previously presented in the TF-A SMC Fuzz testing session a few weeks back and provides a testing approach for a the different level of PSA API testing coming to TF-A. * Optional TF-A Mailing List Topic Discussions If TF-A contributors have anything they wish to present at any future TF-A tech forum please contact me to have that scheduled. Previous sessions, both recording and presentation material can be found on the trustedfirmware.org TF-A Technical meeting webpage: https://www.trustedfirmware.org/meetings/tf-a-technical-forum/ A scheduling tracking page is also available to help track sessions suggested and being prepared: https://developer.trustedfirmware.org/w/tf_a/tf-a-tech-forum-scheduling/ Final decisions on what will be presented will be shared a few days before the next meeting and shared on the TF-A mailing list. Thanks Joanna

5 years, 6 months

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Re: [TF-A] How should we manage patches affecting multiple users?

by Joanna Farley

My take on this is perhaps not unexpectantly fairly aligned with Sandrine's. We as a project have over 30 platforms now up-streamed and the expectations is these are managed by the identified platform owners. We look to them to decide on which of any new capabilities offered are supported in their platforms. We have a strategy not to break up-streamed platforms except where we have clearly announced deprecation and this is all documented here https://trustedfirmware-a.readthedocs.io/en/latest/process/platform-compati… and where interfaces have changed and the work is trivial the submitter is expected to attempt to make a good effort to migrate platforms. To support this the current CI system hosted by Arm can only verify the builds of most platforms which is one of the gerrit approvals needed to merge a patch. Of course that does not mean the executables produced will necessarily run correctly which is where platform owners would need to assist with their own approvals and own testing if possible. With the Arm Juno platform and various Arm FVP models we do have the capability to test but that misses out all the other platforms up-streamed. With the OpenCI coming, which we owe a Tech-Forum session on BTW, the Juno and Arm FVP models will also be made available and if platform owners want they will be able to add their platforms to be tested if they want to invest the effort. Sadly migrating to the OpenCI will take time and will have to be delivered in phases but the hope is this will be useful to platform owners as well as for core changes with the visibility of the CI results. The various Arm platforms are generally owned and managed by different teams and go through the same processes as other non Arm platforms on getting patched up-streamed. So when new core features are added for new Arm hardware IP support or new software features that change behaviour as previously we still look to the platform owners to decide if they want support for these in their platforms. For some trivial changes that may be in the form of reviewing changes prepared but for others that may be deciding if they want to invest the effort to implement themselves. For core changes as well as making patches available via Gerrit for review we have been making more use of the TF-A mailing list to announce the patches are available. Indeed we are trying to make use of the mailing list while work is still in design to discuss openly decisions that need to be made which may or may not effect platforms. The Tech-Forum is also being used to present and discuss ideas and ongoing work. This is all being done to be more open about upcoming changes. We would welcome discussions on the mailing list and tech-forum sessions from platform owners about any subjects. This could be around coordinated support across platforms of new capabilities vs each platform following its own path. That of course holds challenges in coordination of effort and who's effort. Hopefully the direction of travel here for the project helps with some of the suggestions but happy to discuss more here on the mailing list of in a tech-forum meeting. Thanks Joanna On 25/06/2020, 03:16, "TF-A on behalf of Varun Wadekar via TF-A" <tf-a-bounces(a)lists.trustedfirmware.org on behalf of tf-a(a)lists.trustedfirmware.org> wrote: Hi, >> As you said, even a small change might break a platform and unfortunately we're not in a position to detect that with the CI yet. I agree that this is a limitation today. If you remember, I have been advocating for announcing on the email alias when in doubt. That way we minimize surprises for the platform owners. >> IMO we cannot reasonably announce all such changes and I would think that contributors are responsible for keeping an eye on patches and testing them if they think they might be affected. I understand. We should announce on the mailing list, when in doubt. I strongly disagree with the second part of the statement though. Asking platform owners to keep an eye on every change defeats the purpose of upstreaming. The burden must lie on the implementer of a change to try and upgrade consumers. >> But I think that the same change might be considered as an improvement by some, and a useless/undesirable change by others. Possible. And then we take call as a community. If it makes sense for some platforms to move ahead, then that should be OK too. >> We might be able to reduce the number of build options in some cases but there will always be a need to retain most of them IMO Thinking out loud - maybe moving to runtime checks makes sense in some cases instead of makefile variables e.g. CPU erratas. We should look at each case individually. I guess, the main problem seems to be low level of testing. So any implementer wont be confident making a change that affects other platforms. That's when sending an email to the community makes sense. We tackle the situation as a team, instead of one person doing all the work. -Varun -----Original Message----- From: Sandrine Bailleux <sandrine.bailleux(a)arm.com> Sent: Wednesday, June 24, 2020 4:54 AM To: Varun Wadekar <vwadekar(a)nvidia.com> Cc: tf-a(a)lists.trustedfirmware.org Subject: Re: [TF-A] How should we manage patches affecting multiple users? External email: Use caution opening links or attachments Hi Varun, Thanks for sharing your opinion. On 6/20/20 1:55 AM, Varun Wadekar wrote: > Hello @Sandrine Bailleux, > > Thanks for starting the email chain. My response to the issues you flagged in the email below. > > 1. This seems to be a bit tricky. As a consumer of an API, one would expect that it works as advertised. If the behavior changes, thus affecting the expectations or assumptions surrounding the API, then they should be announced. With so many platforms in the tree, we should always assume that even a small change will break a platform. I agree. Whenever there is clear intention to change the expectations or assumptions of an API, this should be announced and discussed. However, there are cases where we might want to rework the implementation of an API (to clean the code for example), make some improvements or extend its functionality. All of that might be done with no intent to step outside of the API original scope but still subtly break some code. As you said, even a small change might break a platform and unfortunately we're not in a position to detect that with the CI yet. IMO we cannot reasonably announce all such changes and I would think that contributors are responsible for keeping an eye on patches and testing them if they think they might be affected. > 2. For improvements, we should strive to upgrade all consumers of the API/makefile/features. This will ensure that all platforms remain current and we reduce maintenance cost in the long run. I assume, that such improvements will give birth to additional configs/makefile settings/platform variables etc. We would be signing up for a lot of maintenance by allowing some platforms to lag. > > For straight forward changes (e.g. the change under discussion) I assume that the platforms will respond and we would get the changes merged relatively fast. For controversial features, this will spark a healthy discussion in the community. I agree with you in principle. But I think that the same change might be considered as an improvement by some, and a useless/undesirable change by others. For example, the change under discussion is an improvement from our point of view. It will lower the maintenance cost, as any new file added in the GIC driver in the future will be automatically pulled in by platforms that use the newly introduced GIC makefile, without the need to update all platforms makefiles. But this might not be what everyone wants, some platform owners might prefer continue cherry-picking specific GIC source files to retain control over what they include in their firmware. In this case, is it the right thing to do to "upgrade" them? I think this is debatable. Maybe a better alternative is to simply make people aware of the change, provide a link to how the migration was done for Arm platforms in this case, so that they've got an example to guide them if they wish to embrace the change for their own platform ports. > 3. For a case where the change breaks platforms, it makes sense to just upgrade all of them. > >>> Now the question we were pondering in Gerrit is, where does the responsibility of migrating all platforms/users lie for all these types of changes? Is the patch author responsible to do all the work? > > [VW] IMO, the author of such a patch is the best person to upgrade all affected platforms/users. The main reason being that he/she is already an expert for the patch. Agree that the patch author is an expert for his own patch but that does not mean he's also an expert on how his patch should be applied for another platform port he's not familiar with. > But, this might not be true in some cases where the author will need help from the community. For such cases, we should ask for help on the mailing list. Yes, I think such cases require collaboration indeed. > I also want to highlight the dangers of introducing make variables as a solution. The current situation is already unmanageable with so many build variables and weak handlers. We should try and avoid adding more. Not sure how this ties with the original discussions but I agree with you, we've got far too many build options in this project. This makes testing a lot harder, as it means we have hundreds of valid combinations of build options to verify. It also makes the code harder to read and understand because it is sprinkled with #ifdefs. Hopefully, switching to a KConfig-like configuration system in the future will help alleviate this issue, as at least it will allow us to express the valid combinations of build options in a more robust manner (today the build system tries to forbid invalid combinations but I am sure it's far from exhaustive in these types of checks) and also visualize what's been enabled/disabled more easily for a specific build. Even though I acknowledge this problem, I am not sure we can completely solve it. Firmware is not general-purpose software and it requires a lot more control over the features you include or not because of stricter memory and CPU constraints. I think people need a way to turn on/off features at a fine granularity. We might be able to reduce the number of build options in some cases but there will always be a need to retain most of them IMO. > Finally, I agree that there's no silver bullet and we have to deal with each situation differently. Communication is key, as you rightly said. As long we involve the community, we should be OK. > > -Varun > > -----Original Message----- > From: TF-A <tf-a-bounces(a)lists.trustedfirmware.org> On Behalf Of > Sandrine Bailleux via TF-A > Sent: Friday, June 19, 2020 2:57 AM > To: tf-a <tf-a(a)lists.trustedfirmware.org> > Subject: [TF-A] How should we manage patches affecting multiple users? > > External email: Use caution opening links or attachments > > > Hello everyone, > > I would like to start a discussion around the way we want to handle changes that affect all platforms/users. This subject came up in this code review [1]. > > I'll present my views on the subject and would like to know what others think. > > First of all, what do we mean by "changes that affect all platforms"? It would be any change that is not self-contained within a platform port. > IOW, a change in some file outside of the plat/ directory. It could be in a driver, in a library, in the build system, in the platform interfaces called by the generic code... the list goes on. > > 1. Some are just implementation changes, they leave the interfaces unchanged. These do not break other platforms builds since the call sites don't need to be updated. However, they potentially change the responsibilities of the interface, in which case this might introduce behavioral changes that all users of the interface need to be aware of and adapt their code to. > > 2. Some other changes might introduce optional improvements. They introduce a new way of doing things, perhaps a cleaner or more efficient one. Users can safely stay with the old way of doing things without fear of breakage but they would benefit from migrating. > > This is the case of Alexei's patch [1], which introduces an > intermediate > GICv2 makefile, that Arm platforms now include instead of pulling each individual file by themselves. At this point, it is just an improvement that introduces an indirection level in the build system. This is an improvement in terms of maintainability because if we add a new essential file to this driver in the future, we'll just need to add it in this new GICv2 makefile without having to update all platforms makefiles. However, platform makefiles can continue to pull in individual files if they wish to. > > 3. Some other changes might break backwards compatibility. This is something we should avoid as much as possible and we should always strive to provide a migration path. But there are cases where there might be no other way than to break things. In this case, all users have to be migrated. > > > Now the question we were pondering in Gerrit is, where does the responsibility of migrating all platforms/users lie for all these types of changes? Is the patch author responsible to do all the work? > > I think it's hard to come up with a one-size-fits-all answer. It really depends on the nature of changes, their consequences, the amount of work needed to do the migration, the ability for the patch author to test these changes, to name a few. > > I believe the patch author should migrate all users on a best-effort basis. If it's manageable then they should do the work and propose a patch to all affected users for them to review and test on their platforms. > > On the other hand, if it's too much work or impractical, then I think the best approach would be for the patch author to announce and discuss the changes on this mailing list. In some scenarios, the changes might be controversial and not all platform owners might agree that the patch brings enough benefit compared to the migration effort, in which case the changes might have to be withdrawn or re-thought. In any case, I believe communication is key here and no one should take any unilateral decision on their own if it affects other users. > > I realize this is a vast subject and that we probably won't come up with an answer/reach an agreement on all the aspects of the question. But I'd be interested in hearing other contributors' view and if they've got any experience managing these kinds of issues, perhaps in other open source project. > > Best regards, > Sandrine > > [1] > https://review.trustedfirmware.org/c/TF-A/trusted-firmware-a/+/4538 > -- > TF-A mailing list > TF-A(a)lists.trustedfirmware.org > https://lists.trustedfirmware.org/mailman/listinfo/tf-a > -- TF-A mailing list TF-A(a)lists.trustedfirmware.org https://lists.trustedfirmware.org/mailman/listinfo/tf-a

5 years, 6 months

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