iommu/amd: Setup GCR3 table in advance if domain is SVA capable

SVA can be supported if domain is in passthrough mode or paging domain
with v2 page table. Current code sets up GCR3 table for domain with v2
page table only. Setup GCR3 table for all SVA capable domains.

  - Move GCR3 init/destroy to separate function.

  - Change default GCR3 table to use MAX supported PASIDs. Ideally it
    should use 1 level PASID table as its using PASID zero only. But we
    don't have support to extend PASID table yet. We will fix this later.

  - When domain is configured with passthrough mode, allocate default GCR3
    table only if device is SVA capable.

Note that in attach_device() path it will not know whether device will use
SVA or not. If device is attached to passthrough domain and if it doesn't
use SVA then GCR3 table will never be used. We will endup wasting memory
allocated for GCR3 table. This is done to avoid DTE update when
attaching PASID to device.

Signed-off-by: Vasant Hegde <[email protected]>
Reviewed-by: Jason Gunthorpe <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: hegdevasant

drivers/iommu/amd/iommu.c

@@ -89,6 +89,21 @@ static inline bool pdom_is_v2_pgtbl_mode(struct protection_domain *pdom)
 	return (pdom && (pdom->pd_mode == PD_MODE_V2));
 }
 
+static inline bool pdom_is_in_pt_mode(struct protection_domain *pdom)
+{
+	return (pdom->domain.type == IOMMU_DOMAIN_IDENTITY);
+}
+
+/*
+ * We cannot support PASID w/ existing v1 page table in the same domain
+ * since it will be nested. However, existing domain w/ v2 page table
+ * or passthrough mode can be used for PASID.
+ */
+static inline bool pdom_is_sva_capable(struct protection_domain *pdom)
+{
+	return pdom_is_v2_pgtbl_mode(pdom) || pdom_is_in_pt_mode(pdom);
+}
+
 static inline int get_acpihid_device_id(struct device *dev,
 					struct acpihid_map_entry **entry)
 {
@@ -1964,6 +1979,58 @@ void amd_iommu_dev_update_dte(struct iommu_dev_data *dev_data, bool set)
 	iommu_completion_wait(iommu);
 }
 
+/*
+ * If domain is SVA capable then initialize GCR3 table. Also if domain is
+ * in v2 page table mode then update GCR3[0].
+ */
+static int init_gcr3_table(struct iommu_dev_data *dev_data,
+			   struct protection_domain *pdom)
+{
+	struct amd_iommu *iommu = get_amd_iommu_from_dev_data(dev_data);
+	int max_pasids = dev_data->max_pasids;
+	int ret = 0;
+
+	 /*
+	  * If domain is in pt mode then setup GCR3 table only if device
+	  * is PASID capable
+	  */
+	if (pdom_is_in_pt_mode(pdom) && !pdev_pasid_supported(dev_data))
+		return ret;
+
+	/*
+	 * By default, setup GCR3 table to support MAX PASIDs
+	 * supported by the device/IOMMU.
+	 */
+	ret = setup_gcr3_table(&dev_data->gcr3_info, iommu,
+			       max_pasids > 0 ?  max_pasids : 1);
+	if (ret)
+		return ret;
+
+	/* Setup GCR3[0] only if domain is setup with v2 page table mode */
+	if (!pdom_is_v2_pgtbl_mode(pdom))
+		return ret;
+
+	ret = update_gcr3(dev_data, 0, iommu_virt_to_phys(pdom->iop.pgd), true);
+	if (ret)
+		free_gcr3_table(&dev_data->gcr3_info);
+
+	return ret;
+}
+
+static void destroy_gcr3_table(struct iommu_dev_data *dev_data,
+			       struct protection_domain *pdom)
+{
+	struct gcr3_tbl_info *gcr3_info = &dev_data->gcr3_info;
+
+	if (pdom_is_v2_pgtbl_mode(pdom))
+		update_gcr3(dev_data, 0, 0, false);
+
+	if (gcr3_info->gcr3_tbl == NULL)
+		return;
+
+	free_gcr3_table(gcr3_info);
+}
+
 static int do_attach(struct iommu_dev_data *dev_data,
 		     struct protection_domain *domain)
 {
@@ -1982,19 +2049,10 @@ static int do_attach(struct iommu_dev_data *dev_data,
 	domain->dev_iommu[iommu->index] += 1;
 	domain->dev_cnt                 += 1;
 
-	/* Init GCR3 table and update device table */
-	if (domain->pd_mode == PD_MODE_V2) {
-		/* By default, setup GCR3 table to support single PASID */
-		ret = setup_gcr3_table(&dev_data->gcr3_info, iommu, 1);
+	if (pdom_is_sva_capable(domain)) {
+		ret = init_gcr3_table(dev_data, domain);
 		if (ret)
 			return ret;
-
-		ret = update_gcr3(dev_data, 0,
-				  iommu_virt_to_phys(domain->iop.pgd), true);
-		if (ret) {
-			free_gcr3_table(&dev_data->gcr3_info);
-			return ret;
-		}
 	}
 
 	/* Update device table */
@@ -2009,10 +2067,8 @@ static void do_detach(struct iommu_dev_data *dev_data)
 	struct amd_iommu *iommu = get_amd_iommu_from_dev_data(dev_data);
 
 	/* Clear GCR3 table */
-	if (domain->pd_mode == PD_MODE_V2) {
-		update_gcr3(dev_data, 0, 0, false);
-		free_gcr3_table(&dev_data->gcr3_info);
-	}
+	if (pdom_is_sva_capable(domain))
+		destroy_gcr3_table(dev_data, domain);
 
 	/* Update data structures */
 	dev_data->domain = NULL;