[PATCH 7/9] drm/xe/vf: Don't use register based TLB invalidation if VF

[Matthew Brost]

On Wed, Jun 19, 2024 at 11:45:55PM +0200, Michal Wajdeczko wrote:
> VF drivers can only use GuC-based TLB invalidation, as they don't
> have access to the related registers. However, VFs shouldn't need
> any explicit TLB invalidation before enabling CTB communication,
> as there will be an implicit GGTT TLB invalidation issued by the
> GuC itself as part of MMIO-based action handling.
> 

Does assigning / removing a new GGTT mapping on a VF involve a MMIO
action?

Not touching registers on VF itself makes sense though.

Matt

> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
> index 23d397a246a8..e1f1ccb01143 100644
> --- a/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
> +++ b/drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c
> @@ -13,6 +13,7 @@
>  #include "xe_guc.h"
>  #include "xe_guc_ct.h"
>  #include "xe_mmio.h"
> +#include "xe_sriov.h"
>  #include "xe_trace.h"
>  #include "regs/xe_guc_regs.h"
>  
> @@ -249,6 +250,9 @@ int xe_gt_tlb_invalidation_ggtt(struct xe_gt *gt)
>  
>  		xe_gt_tlb_invalidation_wait(gt, seqno);
>  	} else if (xe_device_uc_enabled(xe) && !xe_device_wedged(xe)) {
> +		if (IS_SRIOV_VF(xe))
> +			return 0;
> +
>  		xe_gt_WARN_ON(gt, xe_force_wake_get(gt_to_fw(gt), XE_FW_GT));
>  		if (xe->info.platform == XE_PVC || GRAPHICS_VER(xe) >= 20) {
>  			xe_mmio_write32(gt, PVC_GUC_TLB_INV_DESC1,
> -- 
> 2.43.0
>