Re: [PATCH] drm/amdgpu: Gate VFCT bus fallback on pci=realloc

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] pci: missing EXPORT_SYMBOL for pci_realloc_enabled_by_user() breaks amdgpu
--

commit 9eeda1e99dc9a34bbbe5670a252bc894b1208696
Author: Mario Limonciello <mario.limonciello@amd.com>

drm/amdgpu: Gate VFCT bus fallback on pci=realloc

This patch modifies the soft filter system to gate the VFCT bus fallback
so it only runs when pci=realloc is explicitly requested by the user. It
introduces pci_realloc_enabled_by_user() in the PCI core and uses it in
the AMDGPU driver.

Closes: https://lore.kernel.org/amd-gfx/20261014080523.186533-1-rezanikzadch@gmail.com/

> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
> index f9315e0472fe9..9651260278c18 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_bios.c
[ ... ]
> @@ -459,7 +457,10 @@ static int amdgpu_acpi_vfct_match(struct amdgpu_device *adev,
>  	if (vhdr->PCIBus == adev->pdev->bus->number)
>  		return 0;
>  
> -	/* Bus mismatch but device identity matches (PCI renumbering case) */
> +	/* Allow bus renumbering only when the user requested pci=realloc. */
> +	if (!pci_realloc_enabled_by_user())
> +		return -ENODEV;
> +

[ ... ]

> diff --git a/drivers/pci/setup-bus.c b/drivers/pci/setup-bus.c
> index ed16ef7c26fa7..d9450585082c0 100644
> --- a/drivers/pci/setup-bus.c
> +++ b/drivers/pci/setup-bus.c
> @@ -1799,6 +1799,11 @@ static bool pci_realloc_enabled(enum enable_type enable)
>  	return enable >= user_enabled;
>  }
>  
> +bool pci_realloc_enabled_by_user(void)
> +{
> +	return pci_realloc_enable == user_enabled;
> +}
> +

[Severity: Low]
Will this cause a module build failure (undefined reference) if the amdgpu
driver is compiled as a loadable module (CONFIG_DRM_AMDGPU=m)?

Since setup-bus.c is built into the core kernel and pci_realloc_enabled_by_user()
lacks an EXPORT_SYMBOL or EXPORT_SYMBOL_GPL macro, the linker won't be able
to resolve this symbol during modpost for amdgpu.ko.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261015124843.203905-1-mario.limonciello@amd.com?part=1