Re: [PATCH] drm/xe/pf: Keep VF LMEM BAR size low if no VFs enabled

["Michał Winiarski" <michal.winiarski@intel.com>]

On Wed, Sep 02, 2026 at 02:47:51PM +0200, Marcin Bernatowicz wrote:
> When VFs are enabled on dGFX the driver resizes the PF VF_LMEM_BAR to
> fit the requested layout. After VFs are disabled the PF VF BAR
> size is left as-is. On platforms with tight MMIO apertures a
> subsequent unplug/rescan followed by another enable may fail with:
> 
>   "VF BAR …: can't assign; no space"
> 
> because the PCI core reserves address space based on the (now large) VF
> template, often multiplied by totalvfs.
> 
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5937
> Fixes: 94eae6ee4c2d ("drm/xe/pf: Set VF LMEM BAR size")
> Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
> Cc: Michał Wajdeczko <michal.wajdeczko@intel.com>
> Cc: Michał Winiarski <michal.winiarski@intel.com>

Reviewed-by: Michał Winiarski <michal.winiarski@intel.com>

Thanks,
-Michał

> ---
> v3:
>  - rebased to resolve conflicts, no other functional changes were done
> v2:
>  - Rename helper to restore_vf_vram_bar_size() (Michal)
>  - Use xe->sriov.pf.device_total_vfs instead of pci_sriov_get_totalvfs(),
>    which may be capped (Michal)
>  - Switch logging to %pe (Michal)
>  - Call restore unconditionally on enable-fail path (Michal)
>    (drop vf_vram_bar_resized flag)
> ---
>  drivers/gpu/drm/xe/xe_pci_sriov.c | 16 ++++++++++++++++
>  1 file changed, 16 insertions(+)