Re: [Intel-gfx] [PATCH 5/5] drm/i915/uc: Reject doplicate entries in firmware table

["Ceraolo Spurio, Daniele" <daniele.ceraolospurio@intel.com>]

On 4/19/2023 10:12 AM, John Harrison wrote:
> On 4/19/2023 10:02, John Harrison wrote:
>> On 4/18/2023 16:24, Ceraolo Spurio, Daniele wrote:
>>> Typo doplicate in patch title
>>>
>>> On 4/14/2023 5:57 PM, John.C.Harrison@Intel.com wrote:
>>>> From: John Harrison <John.C.Harrison@Intel.com>
>>>>
>>>> It was noticed that duplicte entries in the firmware table could cause
>>>
>>> typo duplicte
>>>
>>>> an infinite loop in the firmware loading code if that entry failed to
>>>> load. Duplicate entries are a bug anyway and so should never happen.
>>>> Ensure they don't by tweaking the table validation code to reject
>>>> duplicates.
>>>
>>> Here you're not really rejecting anything though, just printing an 
>>> error (and even that only if the SELFTEST kconfig is selected). This 
>>> would allow our CI to catch issues with patches sent to our ML, but 
>>> IIRC the reported bug was on a kernel fork. We could disable the FW 
>>> loading is the table for that particular blob type is in an invalid 
>>> state, as it wouldn't be safe to attempt a load in that case anyway.
>> The validation code is rejecting duplicates. Whether the driver loads 
>> or not after a failed validation is another matter.
>>
>> I was basically assuming that CI will fail on the error message and 
>> thus prevent such code ever being merged. But yeah, I guess we don't 
>> run CI on backports to stable kernels and such. Although, I would 
>> hope that anyone pushing patches to a stable kernel would run some 
>> testing on it first!
>>
>> Any thoughts on a good way to fail the load? We don't want to just 
>> pretend that firmware is not wanted/required on the platform and just 
>> load the i915 module without the firmware. Also, what about the 
>> longer plan of moving the validation to a selftest. You can't fail 
>> the load at all then.
> Actually, forgot we already have a INTEL_UC_FIRMWARE_ERROR status. 
> That works fine for aborting the load. So just go with that and drop 
> the plan to move to a selftest?
>
> John.

I do actually like the idea of moving this code to a mock selftest. 
Maybe just add a comment above the tables making clear that duplicated 
entries are not allowed and will break the loading flow?

Daniele

>
>
>>
>> John.
>>
>>>
>>>>
>>>> For full m/m/p files, that can be done by simply tweaking the patch
>>>> level check to reject matching values. For reduced version entries,
>>>> the filename itself must be compared.
>>>>
>>>> Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
>>>> ---
>>>>   drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c | 27 
>>>> +++++++++++++++++++++---
>>>>   1 file changed, 24 insertions(+), 3 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 c589782467265..44829247ef6bc 100644
>>>> --- a/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
>>>> +++ b/drivers/gpu/drm/i915/gt/uc/intel_uc_fw.c
>>>> @@ -319,7 +319,7 @@ static void validate_fw_table_type(struct 
>>>> drm_i915_private *i915, enum intel_uc_
>>>>   {
>>>>       const struct uc_fw_platform_requirement *fw_blobs;
>>>>       u32 fw_count;
>>>> -    int i;
>>>> +    int i, j;
>>>>         if (type >= ARRAY_SIZE(blobs_all)) {
>>>>           drm_err(&i915->drm, "No blob array for %s\n", 
>>>> intel_uc_fw_type_repr(type));
>>>> @@ -334,6 +334,27 @@ static void validate_fw_table_type(struct 
>>>> drm_i915_private *i915, enum intel_uc_
>>>>         /* make sure the list is ordered as expected */
>>>>       for (i = 1; i < fw_count; i++) {
>>>> +        /* Versionless file names must be unique per platform: */
>>>> +        for (j = i + 1; j < fw_count; j++) {
>>>> +            /* Same platform? */
>>>> +            if (fw_blobs[i].p != fw_blobs[j].p)
>>>> +                continue;
>>>> +
>>>> +            if (fw_blobs[i].blob.path != fw_blobs[j].blob.path)
>>>> +                continue;
>>>> +
>>>> +            drm_err(&i915->drm, "Diplicaate %s blobs: %s r%u 
>>>> %s%d.%d.%d [%s] matches %s r%u %s%d.%d.%d [%s]\n",
>>>
>>> Typo Diplicaate
>>>
>>> Daniele
>>>
>>>> + intel_uc_fw_type_repr(type),
>>>> +                intel_platform_name(fw_blobs[j].p), fw_blobs[j].rev,
>>>> +                fw_blobs[j].blob.legacy ? "L" : "v",
>>>> +                fw_blobs[j].blob.major, fw_blobs[j].blob.minor,
>>>> +                fw_blobs[j].blob.patch, fw_blobs[j].blob.path,
>>>> +                intel_platform_name(fw_blobs[i].p), fw_blobs[i].rev,
>>>> +                fw_blobs[i].blob.legacy ? "L" : "v",
>>>> +                fw_blobs[i].blob.major, fw_blobs[i].blob.minor,
>>>> +                fw_blobs[i].blob.patch, fw_blobs[i].blob.path);
>>>> +        }
>>>> +
>>>>           /* Next platform is good: */
>>>>           if (fw_blobs[i].p < fw_blobs[i - 1].p)
>>>>               continue;
>>>> @@ -377,8 +398,8 @@ static void validate_fw_table_type(struct 
>>>> drm_i915_private *i915, enum intel_uc_
>>>>           if (fw_blobs[i].blob.minor != fw_blobs[i - 1].blob.minor)
>>>>               goto bad;
>>>>   -        /* Patch versions must be in order: */
>>>> -        if (fw_blobs[i].blob.patch <= fw_blobs[i - 1].blob.patch)
>>>> +        /* Patch versions must be in order and unique: */
>>>> +        if (fw_blobs[i].blob.patch < fw_blobs[i - 1].blob.patch)
>>>>               continue;
>>>>     bad:
>>>
>>
>