[RFC PATCH 4/5] iommu/arm-smmu-v3: Use pinned VMID for NESTED stage with BTM

@@ -28,6 +28,7 @@
 #include <linux/pci.h>
 #include <linux/pci-ats.h>
 #include <linux/platform_device.h>
+#include <linux/kvm_host.h>
 
 #include <linux/amba/bus.h>
 

@@ -2195,6 +2196,33 @@ static void arm_smmu_bitmap_free(unsigned long *map, int idx)
 	clear_bit(idx, map);
 }
 
+static int arm_smmu_pinned_vmid_get(struct arm_smmu_domain *smmu_domain)
+{
+	struct arm_smmu_master *master;
+
+	master = list_first_entry_or_null(&smmu_domain->devices,
+					  struct arm_smmu_master, domain_head);
+	if (!master)
+		return -EINVAL;
+
+	return kvm_pinned_vmid_get(master->dev);
+}
+
+static int arm_smmu_pinned_vmid_put(struct arm_smmu_domain *smmu_domain)
+{
+	struct arm_smmu_master *master;
+
+	master = list_first_entry_or_null(&smmu_domain->devices,
+					  struct arm_smmu_master, domain_head);
+	if (!master)
+		return -EINVAL;
+
+	if (smmu_domain->s2_cfg.vmid)
+		return kvm_pinned_vmid_put(master->dev);
+
+	return 0;
+}
+
 static void arm_smmu_domain_free(struct iommu_domain *domain)
 {
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);

@@ -2215,8 +2243,11 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 		mutex_unlock(&arm_smmu_asid_lock);
 	}
 	if (s2_cfg->set) {
-		if (s2_cfg->vmid)
-			arm_smmu_bitmap_free(smmu->vmid_map, s2_cfg->vmid);
+		if (s2_cfg->vmid) {
+			if (!(smmu->features & ARM_SMMU_FEAT_BTM) &&
+			    smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
+				arm_smmu_bitmap_free(smmu->vmid_map, s2_cfg->vmid);
+		}
 	}
 
 	kfree(smmu_domain);

@@ -3199,6 +3230,17 @@ static int arm_smmu_attach_pasid_table(struct iommu_domain *domain,
 				!(smmu->features & ARM_SMMU_FEAT_2_LVL_CDTAB))
 			goto out;
 
+		if (smmu->features & ARM_SMMU_FEAT_BTM) {
+			ret = arm_smmu_pinned_vmid_get(smmu_domain);
+			if (ret < 0)
+				goto out;
+
+			if (smmu_domain->s2_cfg.vmid)
+				arm_smmu_bitmap_free(smmu->vmid_map, smmu_domain->s2_cfg.vmid);
+
+			smmu_domain->s2_cfg.vmid = (u16)ret;
+		}
+
 		smmu_domain->s1_cfg.cdcfg.cdtab_dma = cfg->base_ptr;
 		smmu_domain->s1_cfg.s1cdmax = cfg->pasid_bits;
 		smmu_domain->s1_cfg.s1fmt = cfg->vendor_data.smmuv3.s1fmt;

@@ -3221,6 +3263,7 @@ static int arm_smmu_attach_pasid_table(struct iommu_domain *domain,
 static void arm_smmu_detach_pasid_table(struct iommu_domain *domain)
 {
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
+	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	struct arm_smmu_master *master;
 	unsigned long flags;
 

@@ -3237,6 +3280,8 @@ static void arm_smmu_detach_pasid_table(struct iommu_domain *domain)
 		arm_smmu_install_ste_for_dev(master);
 	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
 
+	if (smmu->features & ARM_SMMU_FEAT_BTM)
+		arm_smmu_pinned_vmid_put(smmu_domain);
 unlock:
 	mutex_unlock(&smmu_domain->init_mutex);
 }