Re: [PATCH 1/5] drm/amdgpu: Fix VFCT bus number matching with soft filter

On 7/16/26 07:41, Uwe Kleine-König wrote:
> Hello,
> 
> On Wed, Jul 08, 2026 at 02:35:14PM -0500, Mario Limonciello wrote:
>> On systems where PCI bus renumbering occurs (e.g. pci=realloc,
>> resource conflicts), the runtime bus number may differ from the
>> BIOS POST bus number recorded in the VFCT table. This causes
>> amdgpu_acpi_vfct_bios() to fail finding the VBIOS even though
>> the correct device entry exists.
>>
>> Introduce amdgpu_acpi_vfct_match() which treats the bus number
>> as a soft filter: vendor/device/function identity is the hard
>> requirement, while exact bus match is the preferred path. When
>> bus numbers disagree but device identity matches, accept the
>> VFCT entry and log a dev_notice for diagnostics.
>>
>> Reported-by: Oz Tiram <[email protected]>
>> Closes: https://lore.kernel.org/amd-gfx/[email protected]/
>> Signed-off-by: Mario Limonciello <[email protected]>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c | 45 +++++++++++++++++++++---
>>   1 file changed, 40 insertions(+), 5 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
>> index 3ebdd792feec1..d8fd047295d9d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
>> @@ -377,6 +377,45 @@ static bool amdgpu_read_disabled_bios(struct amdgpu_device *adev)
>>   		false : amdgpu_asic_read_disabled_bios(adev);
>>   }
>>   
>> +/**
>> + * amdgpu_acpi_vfct_match() - Check if a VFCT entry matches the device
>> + * @adev: AMDGPU device
>> + * @vhdr: VFCT image header to check
>> + *
>> + * VFCT entries contain the PCI bus number as recorded during BIOS POST.
>> + * On systems where the kernel renumbers PCI buses (e.g. pci=realloc or
>> + * resource conflicts), the runtime bus number may differ from the POST
>> + * value.  Match by device identity (vendor + device + function) and use
>> + * the bus number as a preference: exact bus match is preferred, but when
>> + * the bus numbers disagree we accept the entry if the device identity
>> + * matches.
>> + *
>> + * Returns: 0 on match, -ENODEV on no match
>> + */
>> +static int amdgpu_acpi_vfct_match(struct amdgpu_device *adev,
>> +				  VFCT_IMAGE_HEADER *vhdr)
>> +{
>> +	/* Vendor and device IDs must always match */
>> +	if (vhdr->VendorID != adev->pdev->vendor ||
>> +	    vhdr->DeviceID != adev->pdev->device)
>> +		return -ENODEV;
>> +
>> +	if (vhdr->PCIDevice != PCI_SLOT(adev->pdev->devfn) ||
>> +	    vhdr->PCIFunction != PCI_FUNC(adev->pdev->devfn))
>> +		return -ENODEV;
>> +
>> +	/* Exact bus number match - preferred */
>> +	if (vhdr->PCIBus == adev->pdev->bus->number)
>> +		return 0;
>> +
>> +	/* Bus mismatch but device identity matches (PCI renumbering case) */
>> +	dev_notice(adev->dev,
>> +		   "VFCT bus number mismatch: table %u != runtime %u, matching by device identity (vendor 0x%04x device 0x%04x)\n",
>> +		   vhdr->PCIBus, adev->pdev->bus->number,
>> +		   adev->pdev->vendor, adev->pdev->device);
>> +	return 0;
>> +}
>> +
>>   #ifdef CONFIG_ACPI
>>   static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
>>   {
>> @@ -413,11 +452,7 @@ static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
>>   		}
>>   
>>   		if (vhdr->ImageLength &&
>> -		    vhdr->PCIBus == adev->pdev->bus->number &&
>> -		    vhdr->PCIDevice == PCI_SLOT(adev->pdev->devfn) &&
>> -		    vhdr->PCIFunction == PCI_FUNC(adev->pdev->devfn) &&
>> -		    vhdr->VendorID == adev->pdev->vendor &&
>> -		    vhdr->DeviceID == adev->pdev->device) {
>> +		    !amdgpu_acpi_vfct_match(adev, vhdr)) {
>>   			adev->bios = kmemdup(&vbios->VbiosContent,
>>   					     vhdr->ImageLength,
>>   					     GFP_KERNEL);
> 
> For the record to hopefully make it easier for others to find the fix:
> 
> This patch became 33a18ecd2fbf in
> 
> 	https://gitlab.freedesktop.org/agd5f/linux.git drm-next
> 
> and thus next and it introduces a build failure for !CONFIG_ACPI builds:
> 
> 	drivers/gpu/drm/radeon/radeon_bios.c:614:12: error: ‘radeon_acpi_vfct_match’ defined but not used [-Werror=unused-function]
> 	  614 | static int radeon_acpi_vfct_match(struct radeon_device *rdev,
> 	      |            ^~~~~~~~~~~~~~~~~~~~~~
> 
> Patch available at https://lore.kernel.org/all/[email protected]/
> 
> Best regards
> Uwe

Thanks.  Alex can you squash that in, or has the merge request already 
gone out?