[Intel-gfx] [PATCH v2 1/1] drm/i915/uc: Fix issues with overriding firmware files

[John Harrison]

On 9/13/2022 17:58, John.C.Harrison at Intel.com wrote:
> From: John Harrison <John.C.Harrison at Intel.com>
>
> The earlier update to support reduced versioning of firmware files
> introduced an issue with the firmware override module parameter. If an
> invalid file was specified then an infinite loop could occur trying to
> find a backup firmware.
The above not entirely correct - got myself confused while typing it up.

A self test would specify an invalid file name (invalid meaning not in 
the table) both with and without setting the override flag. The 
*non-override* case would cause the infinite loop. I.e. a situation that 
is impossible to hit outside of the selftest because either the file 
name has come from the table in first place or it came from an override. 
However, the override case was still broken in that it would bypass some 
of the later processing.

>
> The fix is that if an explicit override has been set, then don't scan
> for backup options because there is no point anyway. The user wanted X
> and if X is not available, that's their problem.
>
> This patch also fixes up the scanning loop code so that if an invalid
> file is passed in, it will exit rather than loop forever. So if the
> impossible situation did somehow occur in the future, it wouldn't be
> such a big problem.
It also flips the logic on the override early exit to be negative rather 
than positive so as not to skip code that still needs to be run.

John.

>
> v2: Also remove ANSI colour codes that accidentally got left in an
> error message in the original patch.
>
> Fixes: 665ae9c9ca79 ("drm/i915/uc: Support for version reduced and multiple
> firmware files")
> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> Cc: Matthew Brost <matthew.brost at intel.com>
> Cc: Umesh Nerlige Ramappa <umesh.nerlige.ramappa at intel.com>
> Cc: Matthew Auld <matthew.auld at intel.com>
> Cc: Alan Previn <alan.previn.teres.alexis at intel.com>
> Cc: Matt Roper <matthew.d.roper at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Cc: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
> Cc: "Thomas Hellström" <thomas.hellstrom at linux.intel.com>
> Cc: Venkata Sandeep Dhanalakota <venkata.s.dhanalakota at intel.com>
> Signed-off-by: John Harrison <John.C.Harrison at Intel.com>
> ---
>   drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 20 +++++++++++++++-----
>   1 file changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> index af425916cdf64..1169e2a09da24 100644
> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
> @@ -232,6 +232,7 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
>   	u32 fw_count;
>   	u8 rev = INTEL_REVID(i915);
>   	int i;
> +	bool found;
>   
>   	/*
>   	 * The only difference between the ADL GuC FWs is the HWConfig support.
> @@ -246,6 +247,7 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
>   	fw_blobs = blobs_all[uc_fw->type].blobs;
>   	fw_count = blobs_all[uc_fw->type].count;
>   
> +	found = false;
>   	for (i = 0; i < fw_count && p <= fw_blobs[i].p; i++) {
>   		const struct uc_fw_blob *blob = &fw_blobs[i].blob;
>   
> @@ -266,9 +268,15 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
>   		uc_fw->file_wanted.path = blob->path;
>   		uc_fw->file_wanted.major_ver = blob->major;
>   		uc_fw->file_wanted.minor_ver = blob->minor;
> +		found = true;
>   		break;
>   	}
>   
> +	if (!found && uc_fw->file_selected.path) {
> +		/* Failed to find a match for the last attempt?! */
> +		uc_fw->file_selected.path = NULL;
> +	}
> +
>   	/* make sure the list is ordered as expected */
>   	if (IS_ENABLED(CONFIG_DRM_I915_SELFTEST) && !verified) {
>   		verified = true;
> @@ -322,7 +330,7 @@ __uc_fw_auto_select(struct drm_i915_private *i915, struct intel_uc_fw *uc_fw)
>   				continue;
>   
>   bad:
> -			drm_err(&i915->drm, "\x1B[35;1mInvalid FW blob order: %s r%u %s%d.%d.%d comes before %s r%u %s%d.%d.%d\n",
> +			drm_err(&i915->drm, "Invalid FW blob order: %s r%u %s%d.%d.%d comes before %s r%u %s%d.%d.%d\n",
>   				intel_platform_name(fw_blobs[i - 1].p), fw_blobs[i - 1].rev,
>   				fw_blobs[i - 1].blob.legacy ? "L" : "v",
>   				fw_blobs[i - 1].blob.major,
> @@ -553,10 +561,14 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
>   
>   	err = firmware_request_nowarn(&fw, uc_fw->file_selected.path, dev);
>   	memcpy(&file_ideal, &uc_fw->file_wanted, sizeof(file_ideal));
> -	if (!err || intel_uc_fw_is_overridden(uc_fw))
> -		goto done;
> +
> +	/* Any error is terminal if overriding. Don't bother searching for older versions */
> +	if (err && intel_uc_fw_is_overridden(uc_fw))
> +		goto fail;
>   
>   	while (err == -ENOENT) {
> +		old_ver = true;
> +
>   		__uc_fw_auto_select(i915, uc_fw);
>   		if (!uc_fw->file_selected.path) {
>   			/*
> @@ -576,8 +588,6 @@ int intel_uc_fw_fetch(struct intel_uc_fw *uc_fw)
>   	if (err)
>   		goto fail;
>   
> -	old_ver = true;
> -done:
>   	if (uc_fw->loaded_via_gsc)
>   		err = check_gsc_manifest(fw, uc_fw);
>   	else