[TF-A] Re: question about encryption

Hi

It seems that 'io_dev_open' is being called within 'check_fip' and 'check_enc_fip' during the retrieval of the image specification. Instead, you can register and open the enc and fip devices once during the setup phase [see example [1] for reference) and store their handles (fip_dev_handle and enc_dev_handle)

These stored handles can then be used directly in the `check_fip` and `check_enc_fip` functions. Please let me know if you need any additional information or if I missed anything in your details.

[1]: https://review.trustedfirmware.org/plugins/gitiles/TF-A/trusted-firmware-a/+...

Thanks, Manish Badarkhe

________________________________ From: 林觀明 via TF-A tf-a@lists.trustedfirmware.org Sent: 18 January 2025 15:56 To: tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org Subject: [TF-A] question about encryption

Hi

I tried to turn on encryption in BL31. And, I met some trouble.

Here is my code.

``` static struct plat_io_policy policies[] = { ... [BL31_IMAGE_ID] = {&enc_dev_handle, &bl31_uuid_spec, check_enc_fip}, .... [ENC_IMAGE_ID] = {&fip_dev_handle, NULL, check_fip} }

int plat_get_image_source(...) { ... policy = &policies[image_id]; ret = policy->check[policy->image_spec]; ... }

static int check_fip(const uintptr_t spec) {

int ret;

ret = io_dev_open(fip_dev_con, (uintptr_t)NULL, &fip_dev_handle);

if (ret) { ERROR("io_dev_open failed for FIP (%d)\n", ret); return ret;   }

ret = io_dev_init(fip_dev_handle, fip_image_id); if (ret) { ERROR("io_dev_init failed for FIP image id %lu (%d)\n", fip_image_id, ret); io_dev_close(fip_dev_handle); } return ret; }

static int check_enc_fip(const uintptr_t spec) {   int result;   uintptr_t local_image_handle;

/* See if a Firmware Image Package is available */   result = io_dev_open(enc_dev_con, (uintptr_t)NULL, &enc_dev_handle);   if (result) {     ERROR("io_dev_open failed for FIP (%d)\n", result);     return result;   }

result = io_dev_init(enc_dev_handle, (uintptr_t)ENC_IMAGE_ID);   if (result != 0)     return result;   return result; } ```

But, I can't boot successfully. Below is log. ``` INFO: Image id=3 loaded: 0x40800000 - 0x4080e299 INFO: BL2: Loading image id 5 WARNING: ===== allocate_dev_info 1 ===== WARNING: ==== -12 ==== ERROR: io_dev_open failed for FIP (-12) ERROR: Image id 11 open failed with -12 WARNING: Failed to obtain reference to image id=11 (-12) ERROR: BL2: Failed to load image id 5 (-12) ```

And, I found root cause in `allocate_dev_info` and `free_dev_info` in `drivers/io/io_fip.c` In `allocate_dev_info`, there is a count, `fip_dev_count`, increasing by 1 after calling `fip_dev_open` There is a check. The value of MAX_FIP_DEVICES is 1. ``` if (fip_dev_count < (unsigned int)MAX_FIP_DEVICES) {     unsigned int index = 0;

result = find_first_fip_state(0, &index);     assert(result == 0);     /* initialize dev_info */     dev_info_pool[index].funcs = &fip_dev_funcs;     dev_info_pool[index].info =         (uintptr_t)&state_pool[index];     *dev_info = &dev_info_pool[index];     ++fip_dev_count;   } ``` And, in `fip_dev_close`, The `fip_dev_count` will be decreased by 1.

However, The root casue is it call fip_dev_open but not calling fip_dev_close. It cause the `fip_dev_count` not be decreased by 1.

Now, I have two solution. 1. Increasing the MAX_FIP_DEVICES, it will be working. 2. Add the io_dev_close in `enc_dev_close` in `driver/io_/io_encrypted.c`. And, it will call the fip_dev_close. It will be working.

Do you have any idea in this solution ? Which solution is more general ?

Thanks !