[PATCH v4 16/27] iommu/arm-smmu-v3: Keep track of valid CD entries in the cd_table

[Jason Gunthorpe]

We no longer need a master->sva_enable to control what attaches are
allowed.

Instead keep track inside the cd_table how many valid CD entries exist,
and if the RID has a valid entry.

Replace all the attach focused master->sva_enabled tests with a check if
the CD has valid entries (or not). If there are any valid entries then the
CD table must be currently programmed to the STE.

Signed-off-by: Jason Gunthorpe <jgg at nvidia.com>
---
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  5 +---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 26 ++++++++++---------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   | 10 +++++++
 3 files changed, 25 insertions(+), 16 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index cd0a8c721d9fba..6d54a6105ceadd 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -433,9 +433,6 @@ static int __arm_smmu_sva_bind(struct device *dev, struct mm_struct *mm,
 	if (smmu_domain->stage != ARM_SMMU_DOMAIN_S1)
 		return -ENODEV;
 
-	if (!master || !master->sva_enabled)
-		return -ENODEV;
-
 	bond = kzalloc(sizeof(*bond), GFP_KERNEL);
 	if (!bond)
 		return -ENOMEM;
@@ -638,7 +635,7 @@ static int arm_smmu_sva_set_dev_pasid(struct iommu_domain *domain,
 	struct mm_struct *mm = domain->mm;
 	struct arm_smmu_cd target;
 
-	if (mm_get_enqcmd_pasid(mm) != id)
+	if (mm_get_enqcmd_pasid(mm) != id || !master->cd_table.used_sid)
 		return -EINVAL;
 
 	if (!arm_smmu_get_cd_ptr(master, id))
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 53b2d2b35a440b..0c134d535401e5 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1245,6 +1245,8 @@ void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
 			     struct arm_smmu_cd *cdptr,
 			     const struct arm_smmu_cd *target)
 {
+	bool target_valid = target->data[0] & cpu_to_le64(CTXDESC_CD_0_V);
+	bool cur_valid = cdptr->data[0] & cpu_to_le64(CTXDESC_CD_0_V);
 	struct arm_smmu_cd_writer cd_writer = {
 		.writer = {
 			.ops = &arm_smmu_cd_writer_ops,
@@ -1253,6 +1255,15 @@ void arm_smmu_write_cd_entry(struct arm_smmu_master *master, int ssid,
 		.ssid = ssid,
 	};
 
+	if (cur_valid != target_valid) {
+		if (cur_valid)
+			master->cd_table.used_ssids--;
+		else
+			master->cd_table.used_ssids++;
+	}
+	if (ssid == IOMMU_NO_PASID)
+		master->cd_table.used_sid = target_valid;
+
 	arm_smmu_write_entry(&cd_writer.writer, cdptr->data, target->data);
 }
 
@@ -2714,16 +2725,6 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	master = dev_iommu_priv_get(dev);
 	smmu = master->smmu;
 
-	/*
-	 * Checking that SVA is disabled ensures that this device isn't bound to
-	 * any mm, and can be safely detached from its old domain. Bonds cannot
-	 * be removed concurrently since we're holding the group mutex.
-	 */
-	if (arm_smmu_master_sva_enabled(master)) {
-		dev_err(dev, "cannot attach - SVA enabled\n");
-		return -EBUSY;
-	}
-
 	mutex_lock(&smmu_domain->init_mutex);
 
 	if (!smmu_domain->smmu) {
@@ -2739,7 +2740,8 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 		cdptr = arm_smmu_get_cd_ptr(master, IOMMU_NO_PASID);
 		if (!cdptr)
 			return -ENOMEM;
-	}
+	} else if (arm_smmu_ssids_in_use(&master->cd_table))
+		return -EBUSY;
 
 	/*
 	 * Prevent arm_smmu_share_asid() from trying to change the ASID
@@ -2815,7 +2817,7 @@ static int arm_smmu_attach_dev_ste(struct iommu_domain *domain,
 	struct arm_smmu_master *master = dev_iommu_priv_get(dev);
 	struct attach_state state = {};
 
-	if (arm_smmu_master_sva_enabled(master))
+	if (arm_smmu_ssids_in_use(&master->cd_table))
 		return -EBUSY;
 
 	/*
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 174e9f080066cc..69351386dc1441 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -602,11 +602,21 @@ struct arm_smmu_ctx_desc_cfg {
 	dma_addr_t			cdtab_dma;
 	struct arm_smmu_l1_ctx_desc	*l1_desc;
 	unsigned int			num_l1_ents;
+	unsigned int			used_ssids;
+	bool				used_sid;
 	u8				s1fmt;
 	/* log2 of the maximum number of CDs supported by this table */
 	u8				s1cdmax;
 };
 
+/* True if the cd table has SSIDS > 0 in use. */
+static inline bool arm_smmu_ssids_in_use(struct arm_smmu_ctx_desc_cfg *cd_table)
+{
+	if (cd_table->used_sid)
+		return cd_table->used_ssids > 1;
+	return cd_table->used_ssids;
+}
+
 struct arm_smmu_s2_cfg {
 	u16				vmid;
 };
-- 
2.43.0