[Intel-gfx] [PATCH 5/5] drm/i915/uc: Reject doplicate entries in firmware table
John Harrison
john.c.harrison at intel.com
Wed Apr 19 17:59:33 UTC 2023
On 4/19/2023 10:33, Ceraolo Spurio, Daniele wrote:
> 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 at Intel.com wrote:
>>>>> From: John Harrison <John.C.Harrison at 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?
The point is about accidental breakages. The 'issue' was not an actual
failure but that a failure could potentially occur if, for example, a
patch got applied twice due to some backport error/confusion. Adding a
comment doesn't help with that.
Given that it is trivial to return FIRMWARE_ERROR on a validation
failure, I'm inclined to go with that for now. The validation is still
only being done once (and moving it to _early time means we don't
actually need the static bool at all) and the driver is guaranteed to
not try to process a broken table and get confused. It is also instantly
evident if a backport is broken for any reason without worrying about
what kind of explicit testing may or may not be run.
John.
>
> 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 at 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:
>>>>
>>>
>>
>
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