[PATCH 1/1] iommu/vt-d: Use real PASID for flush in caching mode

From: Lu Baolu <baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
To: David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Joerg Roedel <joro-zLv9SwRftAIdnm+yROfE0A@public.gmane.org>
Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org
Subject: [PATCH 1/1] iommu/vt-d: Use real PASID for flush in caching mode
Date: Fri, 16 Mar 2018 12:31:36 +0800	[thread overview]
Message-ID: <1521174696-22495-1-git-send-email-baolu.lu@linux.intel.com> (raw)

If caching mode is supported, the hardware will cache
none-present or erroneous translation entries. Hence,
software should explicitly invalidate the PASID cache
after a PASID table entry becomes present. We should
issue such invalidation with the PASID value that we
have changed. PASID 0 is not reserved for this case.

Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
Cc: Kevin Tian <kevin.tian@intel.com>
Cc: Sankaran Rajesh <rajesh.sankaran@intel.com>
Suggested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
---
 drivers/iommu/intel-svm.c | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
index 99bc9bd..b7b88b5 100644
--- a/drivers/iommu/intel-svm.c
+++ b/drivers/iommu/intel-svm.c
@@ -422,17 +422,13 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
 		iommu->pasid_table[svm->pasid].val = pasid_entry_val;
 
 		wmb();
-		/* In caching mode, we still have to flush with PASID 0 when
-		 * a PASID table entry becomes present. Not entirely clear
-		 * *why* that would be the case — surely we could just issue
-		 * a flush with the PASID value that we've changed? The PASID
-		 * is the index into the table, after all. It's not like domain
-		 * IDs in the case of the equivalent context-entry change in
-		 * caching mode. And for that matter it's not entirely clear why
-		 * a VMM would be in the business of caching the PASID table
-		 * anyway. Surely that can be left entirely to the guest? */
+
+		/*
+		 * Flush PASID cache when a PASID table entry becomes
+		 * present.
+		 */
 		if (cap_caching_mode(iommu->cap))
-			intel_flush_pasid_dev(svm, sdev, 0);
+			intel_flush_pasid_dev(svm, sdev, svm->pasid);
 	}
 	list_add_rcu(&sdev->list, &svm->devs);
 
-- 
2.7.4

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