linux-kernel - [PATCH 1/2] iommu/vt-d: Avoid iova flush queue in strict mode

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Date:   Thu, 19 Dec 2019 13:18:50 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Joerg Roedel <joro@...tes.org>
Cc:     David Woodhouse <dwmw2@...radead.org>, ashok.raj@...el.com,
        jacob.jun.pan@...el.com, kevin.tian@...el.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH 1/2] iommu/vt-d: Avoid iova flush queue in strict mode

If Intel IOMMU strict mode is enabled by users, it's unnecessary
to create the iova flush queue.

Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 drivers/iommu/intel-iommu.c | 24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 0726705d2d89..93e1d7c3ac7c 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1858,10 +1858,12 @@ static int domain_init(struct dmar_domain *domain, struct intel_iommu *iommu,
 
 	init_iova_domain(&domain->iovad, VTD_PAGE_SIZE, IOVA_START_PFN);
 
-	err = init_iova_flush_queue(&domain->iovad,
-				    iommu_flush_iova, iova_entry_free);
-	if (err)
-		return err;
+	if (!intel_iommu_strict) {
+		err = init_iova_flush_queue(&domain->iovad,
+					    iommu_flush_iova, iova_entry_free);
+		if (err)
+			return err;
+	}
 
 	domain_reserve_special_ranges(domain);
 
@@ -5199,6 +5201,7 @@ static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
 {
 	struct dmar_domain *dmar_domain;
 	struct iommu_domain *domain;
+	int ret;
 
 	switch (type) {
 	case IOMMU_DOMAIN_DMA:
@@ -5215,11 +5218,14 @@ static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
 			return NULL;
 		}
 
-		if (type == IOMMU_DOMAIN_DMA &&
-		    init_iova_flush_queue(&dmar_domain->iovad,
-					  iommu_flush_iova, iova_entry_free)) {
-			pr_warn("iova flush queue initialization failed\n");
-			intel_iommu_strict = 1;
+		if (!intel_iommu_strict && type == IOMMU_DOMAIN_DMA) {
+			ret = init_iova_flush_queue(&dmar_domain->iovad,
+						    iommu_flush_iova,
+						    iova_entry_free);
+			if (ret) {
+				pr_warn("iova flush queue initialization failed\n");
+				intel_iommu_strict = 1;
+			}
 		}
 
 		domain_update_iommu_cap(dmar_domain);
-- 
2.17.1