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

On Thu, Jul 16, 2026 at 9:21 AM Mario Limonciello
<[email protected]> wrote:
>
>
>
> 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?

Already out.  I've picked up Uwe's patch.

Alex