iommu/vt-d: Make intel_iommu_drain_pasid_prq() cover faults for RID

JIRA: https://issues.redhat.com/browse/RHEL-78704
Upstream Status: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

commit add43c4
Author: Lu Baolu <baolu.lu@linux.intel.com>
Date:   Tue Feb 11 08:55:12 2025 +0800

    iommu/vt-d: Make intel_iommu_drain_pasid_prq() cover faults for RID

    This driver supports page faults on PCI RID since commit <9f831c16c69e>
    ("iommu/vt-d: Remove the pasid present check in prq_event_thread") by
    allowing the reporting of page faults with the pasid_present field cleared
    to the upper layer for further handling. The fundamental assumption here
    is that the detach or replace operations act as a fence for page faults.
    This implies that all pending page faults associated with a specific RID
    or PASID are flushed when a domain is detached or replaced from a device
    RID or PASID.

    However, the intel_iommu_drain_pasid_prq() helper does not correctly
    handle faults for RID. This leads to faults potentially remaining pending
    in the iommu hardware queue even after the domain is detached, thereby
    violating the aforementioned assumption.

    Fix this issue by extending intel_iommu_drain_pasid_prq() to cover faults
    for RID.

    Fixes: 9f831c1 ("iommu/vt-d: Remove the pasid present check in prq_event_thread")
    Cc: stable@vger.kernel.org
    Suggested-by: Kevin Tian <kevin.tian@intel.com>
    Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    Reviewed-by: Kevin Tian <kevin.tian@intel.com>
    Link: https://lore.kernel.org/r/20250121023150.815972-1-baolu.lu@linux.intel.com
    Reviewed-by: Yi Liu <yi.l.liu@intel.com>
    Link: https://lore.kernel.org/r/20250211005512.985563-2-baolu.lu@linux.intel.com
    Signed-off-by: Joerg Roedel <jroedel@suse.de>

(cherry picked from commit add43c4)
Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>

Author: snits

drivers/iommu/intel/prq.c

@@ -87,7 +87,9 @@ void intel_iommu_drain_pasid_prq(struct device *dev, u32 pasid)
 		struct page_req_dsc *req;
 
 		req = &iommu->prq[head / sizeof(*req)];
-		if (!req->pasid_present || req->pasid != pasid) {
+		if (req->rid != sid ||
+		    (req->pasid_present && pasid != req->pasid) ||
+		    (!req->pasid_present && pasid != IOMMU_NO_PASID)) {
 			head = (head + sizeof(*req)) & PRQ_RING_MASK;
 			continue;
 		}