[PATCH] intel/vt-d: Send Page Request Drain only if supported

[Joel Granados]

The intel_iommu_drain_pasid_prq function sends QI_OPT_WAIT_DRAIN to
hardware without verifying Page Request Drain Support (PDS). According
to VT-d specification section 6.5.2.8, PRQ drain functionality should
only be used when PDS (bit 42) is set in the extended capability
register. Add ecap_pds() check to conditionally use QI_OPT_WAIT_DRAIN
based on hardware capability.

Signed-off-by: Joel Granados <joel.granados@xxxxxxxxxx>
---
 drivers/iommu/intel/prq.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/prq.c b/drivers/iommu/intel/prq.c
index 52570e42a14c05b7492957909568805dc9c7b6ef..f89916de31a3439866f059f5400e45fb362a6a7d 100644
--- a/drivers/iommu/intel/prq.c
+++ b/drivers/iommu/intel/prq.c
@@ -119,7 +119,7 @@ void intel_iommu_drain_pasid_prq(struct device *dev, u32 pasid)
 	}
 qi_retry:
 	reinit_completion(&iommu->prq_complete);
-	qi_submit_sync(iommu, desc, 3, QI_OPT_WAIT_DRAIN);
+	qi_submit_sync(iommu, desc, 3, ecap_pds(iommu->ecap) ? QI_OPT_WAIT_DRAIN : 0);
 	if (readl(iommu->reg + DMAR_PRS_REG) & DMA_PRS_PRO) {
 		wait_for_completion(&iommu->prq_complete);
 		goto qi_retry;

---
base-commit: f777d1112ee597d7f7dd3ca232220873a34ad0c8
change-id: 20250909-jag-pds-7d85b60ad9d2

Best regards,
-- 
Joel Granados <joel.granados@xxxxxxxxxx>