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

[Shameer Kolothum]

If the SMMU supports BTM and the device belongs to NESTED domain
with shared pasid table, we need to use the VMID allocated by the
KVM for the s2 configuration. Hence, request a pinned VMID from KVM.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi at huawei.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 49 ++++++++++++++++++++-
 1 file changed, 47 insertions(+), 2 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 26bf7da1bcd0..04f83f7c8319 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -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);
 }
-- 
2.17.1