linux-kernel - [PATCH v10 11/13] iommu/smmuv3: Enforce incompatibility between nested mode and HW MSI regions

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Message-Id: <20200320160932.27222-12-eric.auger@redhat.com>
Date:   Fri, 20 Mar 2020 17:09:30 +0100
From:   Eric Auger <eric.auger@...hat.com>
To:     eric.auger.pro@...il.com, eric.auger@...hat.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, joro@...tes.org,
        alex.williamson@...hat.com, jacob.jun.pan@...ux.intel.com,
        yi.l.liu@...el.com, jean-philippe.brucker@....com,
        will.deacon@....com, robin.murphy@....com
Cc:     marc.zyngier@....com, peter.maydell@...aro.org,
        zhangfei.gao@...il.com
Subject: [PATCH v10 11/13] iommu/smmuv3: Enforce incompatibility between nested mode and HW MSI regions

Nested mode currently is not compatible with HW MSI reserved regions.
Indeed MSI transactions targeting this MSI doorbells bypass the SMMU.

Let's check nested mode is not attempted in such configuration.

Signed-off-by: Eric Auger <eric.auger@...hat.com>
---
 drivers/iommu/arm-smmu-v3.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 84dce0b2e935..106f9c563823 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -2921,6 +2921,23 @@ static bool arm_smmu_share_msi_domain(struct iommu_domain *domain,
 	return share;
 }
 
+static bool arm_smmu_has_hw_msi_resv_region(struct device *dev)
+{
+	struct iommu_resv_region *region;
+	bool has_msi_resv_region = false;
+	LIST_HEAD(resv_regions);
+
+	iommu_get_resv_regions(dev, &resv_regions);
+	list_for_each_entry(region, &resv_regions, list) {
+		if (region->type == IOMMU_RESV_MSI) {
+			has_msi_resv_region = true;
+			break;
+		}
+	}
+	iommu_put_resv_regions(dev, &resv_regions);
+	return has_msi_resv_region;
+}
+
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 {
 	int ret = 0;
@@ -2965,10 +2982,12 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	/*
 	 * In nested mode we must check all devices belonging to the
 	 * domain share the same physical MSI doorbell. Otherwise nested
-	 * stage MSI binding is not supported.
+	 * stage MSI binding is not supported. Also nested mode is not
+	 * compatible with MSI HW reserved regions.
 	 */
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED &&
-		!arm_smmu_share_msi_domain(domain, dev)) {
+		(!arm_smmu_share_msi_domain(domain, dev) ||
+		 arm_smmu_has_hw_msi_resv_region(dev))) {
 		ret = -EINVAL;
 		goto out_unlock;
 	}
-- 
2.20.1