[RFC PATCH v2 6/7] iommu/arm-smmu-v3: Use KVM VMID for s2 stage

[Shameer Kolothum]

If kvm is available make use of kvm pinned VMID interfaces to
set the s2 stage VMID for nested domains.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 18 +++++++++++++-----
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  2 ++
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index b41d77787a2f..18e3e04b50f4 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -18,6 +18,7 @@
 #include <linux/interrupt.h>
 #include <linux/io-pgtable.h>
 #include <linux/iopoll.h>
+#include <linux/kvm_host.h>
 #include <linux/module.h>
 #include <linux/msi.h>
 #include <linux/of.h>
@@ -2399,9 +2400,13 @@ int arm_smmu_domain_alloc_id(struct arm_smmu_device *smmu,
 	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S2) {
 		int vmid;
 
-		/* Reserve VMID 0 for stage-2 bypass STEs */
-		vmid = ida_alloc_range(&smmu->vmid_map, 1,
-				       (1 << smmu->vmid_bits) - 1, GFP_KERNEL);
+		if (smmu_domain->kvm) {
+			vmid = kvm_pinned_vmid_get(smmu_domain->kvm);
+		} else {
+			/* Reserve VMID 0 for stage-2 bypass STEs */
+			vmid = ida_alloc_range(&smmu->vmid_map, 1,
+					       (1 << smmu->vmid_bits) - 1, GFP_KERNEL);
+		}
 		if (vmid < 0)
 			return vmid;
 		smmu_domain->vmid = vmid;
@@ -2431,7 +2436,10 @@ void arm_smmu_domain_free_id(struct arm_smmu_domain *smmu_domain)
 	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S2 &&
 		   smmu_domain->vmid) {
 		arm_smmu_tlb_inv_all_s2(smmu_domain);
-		ida_free(&smmu->vmid_map, smmu_domain->vmid);
+		if (smmu_domain->kvm)
+			kvm_pinned_vmid_put(smmu_domain->kvm);
+		else
+			ida_free(&smmu->vmid_map, smmu_domain->vmid);
 	}
 }
 
@@ -3217,7 +3225,7 @@ arm_smmu_domain_alloc_user(struct device *dev, u32 flags,
 			goto err_free;
 		}
 		smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
-		smmu_domain->nesting_parent = true;
+		smmu_domain->kvm = kvm;
 	}
 
 	smmu_domain->domain.type = IOMMU_DOMAIN_UNMANAGED;
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index 45bcd72fcda4..7d732ea2a6ee 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -758,6 +758,8 @@ struct arm_smmu_domain {
 	struct mmu_notifier		mmu_notifier;
 	bool				btm_invalidation : 1;
 	bool				nesting_parent : 1;
+
+	struct kvm			*kvm;
 };
 
 struct arm_smmu_nested_domain {
-- 
2.34.1