iommu/amd: Fix IOMMU page flush when detach device from a domain

ssuthiku-amd · joergroedel · commit 9825bd94e3a2 · 2019-01-24T15:24:49.000+01:00
When a VM is terminated, the VFIO driver detaches all pass-through devices from VFIO domain by clearing domain id and page table root pointer from each device table entry (DTE), and then invalidates the DTE. Then, the VFIO driver unmap pages and invalidate IOMMU pages. Currently, the IOMMU driver keeps track of which IOMMU and how many devices are attached to the domain. When invalidate IOMMU pages, the driver checks if the IOMMU is still attached to the domain before issuing the invalidate page command. However, since VFIO has already detached all devices from the domain, the subsequent INVALIDATE_IOMMU_PAGES commands are being skipped as there is no IOMMU attached to the domain. This results in data corruption and could cause the PCI device to end up in indeterministic state. Fix this by invalidate IOMMU pages when detach a device, and before decrementing the per-domain device reference counts. Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Suggested-by: Joerg Roedel <joro@8bytes.org> Co-developed-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com> Signed-off-by: Suravee Suthikulpanit <suravee.suthikulpanit@amd.com> Fixes: 6de8ad9 ('x86/amd-iommu: Make iommu_flush_pages aware of multiple IOMMUs') Signed-off-by: Joerg Roedel <jroedel@suse.de>
diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
@@ -1991,16 +1991,13 @@ static void do_attach(struct iommu_dev_data *dev_data,
 
 static void do_detach(struct iommu_dev_data *dev_data)
 {
+	struct protection_domain *domain = dev_data->domain;
 	struct amd_iommu *iommu;
 	u16 alias;
 
 	iommu = amd_iommu_rlookup_table[dev_data->devid];
 	alias = dev_data->alias;
 
-	/* decrease reference counters */
-	dev_data->domain->dev_iommu[iommu->index] -= 1;
-	dev_data->domain->dev_cnt                 -= 1;
-
 	/* Update data structures */
 	dev_data->domain = NULL;
 	list_del(&dev_data->list);
@@ -2010,6 +2007,16 @@ static void do_detach(struct iommu_dev_data *dev_data)
 
 	/* Flush the DTE entry */
 	device_flush_dte(dev_data);
+
+	/* Flush IOTLB */
+	domain_flush_tlb_pde(domain);
+
+	/* Wait for the flushes to finish */
+	domain_flush_complete(domain);
+
+	/* decrease reference counters - needs to happen after the flushes */
+	domain->dev_iommu[iommu->index] -= 1;
+	domain->dev_cnt                 -= 1;
 }
 
 /*
