[PATCH 3/4] iommu/vt-d: Reject unsupported page request modes

[Jacob Pan]

When supervisor/privilige mode SVM is used, we bind init_mm.pgd with
a supervisor PASID. There should not be any page fault for init_mm.
Execution request with DMA read is also not supported.

This patch checks PRQ descriptor for both unsupported configurations,
reject them both with invalid responses.

Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
---
 drivers/iommu/intel/svm.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c
index 23a1e4f58c54..ff7ae7cc17d5 100644
--- a/drivers/iommu/intel/svm.c
+++ b/drivers/iommu/intel/svm.c
@@ -1113,7 +1113,17 @@ static irqreturn_t prq_event_thread(int irq, void *d)
 			       ((unsigned long long *)req)[1]);
 			goto no_pasid;
 		}
-
+		/* We shall not receive page request for supervisor SVM */
+		if (req->pm_req && (req->rd_req | req->wr_req)) {
+			pr_err("Unexpected page request in Privilege Mode");
+			/* No need to find the matching sdev as for bad_req */
+			goto no_pasid;
+		}
+		/* DMA read with exec requeset is not supported. */
+		if (req->exe_req && req->rd_req) {
+			pr_err("Execution request not supported\n");
+			goto no_pasid;
+		}
 		if (!svm || svm->pasid != req->pasid) {
 			rcu_read_lock();
 			svm = ioasid_find(NULL, req->pasid, NULL);
-- 
2.25.1