Re: [PATCH v3 2/3] drm/amdgpu: Match VFCT using initial PCI bus number

[Mario Limonciello <mario.limonciello@amd.com>]

On 10/26/26 10:48, Mario Limonciello wrote:
> VFCT records the PCI bus number from BIOS POST. The current bus number
> can change after PCI core renumbers the bus, while accepting a mismatch
> based only on device identity can select the wrong VFCT image when
> matching devices are present. Compare against the bus number captured
> from the firmware bus assignment before bridge renumbering.
> 
> Reported-by: Reza Nikzad Chaleshori <rezanikzadch@gmail.com>
> Closes: https://lore.kernel.org/amd-gfx/20261014080523.186533-1-rezanikzadch@gmail.com/
> Fixes: 11c141672045f ("drm/amdgpu: Fix VFCT bus number matching with soft filter")
> Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>

Accidentally lost Alex's tag when I rebased.

Reviewed-by: Alex Deucher <alexander.deucher@amd.com>> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c | 17 +++--------------
>   1 file changed, 3 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
> index 08ed1eb695586..051be1905e296 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
> @@ -386,10 +386,8 @@ static bool amdgpu_read_disabled_bios(struct amdgpu_device *adev)
>    * 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.
> + * value.  Match using the bus number captured when the device was
> + * discovered, before any bus renumbering.
>    *
>    * Returns: 0 on match, -ENODEV on no match
>    */
> @@ -405,16 +403,7 @@ static int amdgpu_acpi_vfct_match(struct amdgpu_device *adev,
>   	    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;
> +	return vhdr->PCIBus == adev->pdev->bus->number_initial ? 0 : -ENODEV;
>   }
>   
>   static bool amdgpu_acpi_vfct_bios(struct amdgpu_device *adev)
>