[PATCH v7 6/9] iommu/arm-smmu-v3: Move CD table to arm_smmu_master

[Michael Shavit]

With this change, each master will now own its own CD table instead of
sharing one with other masters attached to the same domain. Attaching a
stage 1 domain installs CD entries into the master's CD table. SVA
writes its CD entries into each master's CD table if the domain is
shared across masters.

Also add the device to the devices list before writing the CD to the
table so that SVA will know that the CD needs to be re-written to this
device's CD table as well if it decides to update the CD's ASID
concurrently with this function.

Tested-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Michael Shavit <mshavit@xxxxxxxxxx>
---

Changes in v7:
- Update commit message to be more clear about locking purpose.
- Removed redundant newline

Changes in v6:
- Grab the asid lock while writing the RID CD to prevent a race with
  SVA.
- Add the device to the devices list before writing the CD to the table
  and installing the CD table.
- Undo arm_smmu_finalise_s1 rename
- Minor comment fix
- Consistently check cdtab pointer instead of cdtab_dma

Changes in v5:
- Clear the 0th CD entry when the domain is detached. Not clearing it
  caused a bug in arm_smmu_write_ctx_desc which doesn't expect the entry
  to already be set.

Changes in v4:
- Added comment about the cd_table's dependency on the iommu core's
  group mutex.
- Narrowed the range of code for which the domain's init_mutex is held
  on attach since it now only protects the arm_smmu_domain_finalise
  call.

Changes in v2:
- Allocate CD table when it's first needed instead of on probe.

Changes in v1:
- The master's CD table allocation was previously split to a different
  commit. This change now atomically allocates the new CD table, uses
  it, and removes the old one.

 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 100 +++++++++++---------
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |   7 +-
 2 files changed, 58 insertions(+), 49 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 69b9bb5c7f773..bcc94a67640d6 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1025,7 +1025,7 @@ static __le64 *arm_smmu_get_cd_ptr(struct arm_smmu_master *master, u32 ssid)
 	unsigned int idx;
 	struct arm_smmu_l1_ctx_desc *l1_desc;
 	struct arm_smmu_device *smmu = master->smmu;
-	struct arm_smmu_ctx_desc_cfg *cdcfg = &master->domain->cd_table;
+	struct arm_smmu_ctx_desc_cfg *cdcfg = &master->cd_table;
 
 	if (cdcfg->s1fmt == STRTAB_STE_0_S1FMT_LINEAR)
 		return cdcfg->cdtab + ssid * CTXDESC_CD_DWORDS;
@@ -1062,7 +1062,7 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_master *master, int ssid,
 	u64 val;
 	bool cd_live;
 	__le64 *cdptr;
-	struct arm_smmu_ctx_desc_cfg *cd_table = &master->domain->cd_table;
+	struct arm_smmu_ctx_desc_cfg *cd_table = &master->cd_table;
 
 	if (WARN_ON(ssid >= (1 << cd_table->s1cdmax)))
 		return -E2BIG;
@@ -1125,14 +1125,13 @@ int arm_smmu_write_ctx_desc(struct arm_smmu_master *master, int ssid,
 	return 0;
 }
 
-static int arm_smmu_alloc_cd_tables(struct arm_smmu_domain *smmu_domain,
-				    struct arm_smmu_master *master)
+static int arm_smmu_alloc_cd_tables(struct arm_smmu_master *master)
 {
 	int ret;
 	size_t l1size;
 	size_t max_contexts;
 	struct arm_smmu_device *smmu = master->smmu;
-	struct arm_smmu_ctx_desc_cfg *cdcfg = &smmu_domain->cd_table;
+	struct arm_smmu_ctx_desc_cfg *cdcfg = &master->cd_table;
 
 	cdcfg->stall_enabled = master->stall_enabled;
 	cdcfg->s1cdmax = master->ssid_bits;
@@ -1176,12 +1175,12 @@ static int arm_smmu_alloc_cd_tables(struct arm_smmu_domain *smmu_domain,
 	return ret;
 }
 
-static void arm_smmu_free_cd_tables(struct arm_smmu_domain *smmu_domain)
+static void arm_smmu_free_cd_tables(struct arm_smmu_master *master)
 {
 	int i;
 	size_t size, l1size;
-	struct arm_smmu_device *smmu = smmu_domain->smmu;
-	struct arm_smmu_ctx_desc_cfg *cdcfg = &smmu_domain->cd_table;
+	struct arm_smmu_device *smmu = master->smmu;
+	struct arm_smmu_ctx_desc_cfg *cdcfg = &master->cd_table;
 
 	if (cdcfg->l1_desc) {
 		size = CTXDESC_L2_ENTRIES * (CTXDESC_CD_DWORDS << 3);
@@ -1289,7 +1288,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
 	if (smmu_domain) {
 		switch (smmu_domain->stage) {
 		case ARM_SMMU_DOMAIN_S1:
-			cd_table = &smmu_domain->cd_table;
+			cd_table = &master->cd_table;
 			break;
 		case ARM_SMMU_DOMAIN_S2:
 		case ARM_SMMU_DOMAIN_NESTED:
@@ -2075,14 +2074,10 @@ static void arm_smmu_domain_free(struct iommu_domain *domain)
 
 	free_io_pgtable_ops(smmu_domain->pgtbl_ops);
 
-	/* Free the CD and ASID, if we allocated them */
+	/* Free the ASID or VMID */
 	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
-		struct arm_smmu_ctx_desc_cfg *cd_table = &smmu_domain->cd_table;
-
 		/* Prevent SVA from touching the CD while we're freeing it */
 		mutex_lock(&arm_smmu_asid_lock);
-		if (cd_table->cdtab)
-			arm_smmu_free_cd_tables(smmu_domain);
 		arm_smmu_free_asid(&smmu_domain->cd);
 		mutex_unlock(&arm_smmu_asid_lock);
 	} else {
@@ -2113,10 +2108,6 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 	if (ret)
 		goto out_unlock;
 
-	ret = arm_smmu_alloc_cd_tables(smmu_domain, master);
-	if (ret)
-		goto out_free_asid;
-
 	cd->asid	= (u16)asid;
 	cd->ttbr	= pgtbl_cfg->arm_lpae_s1_cfg.ttbr;
 	cd->tcr		= FIELD_PREP(CTXDESC_CD_0_TCR_T0SZ, tcr->tsz) |
@@ -2128,17 +2119,9 @@ static int arm_smmu_domain_finalise_s1(struct arm_smmu_domain *smmu_domain,
 			  CTXDESC_CD_0_TCR_EPD1 | CTXDESC_CD_0_AA64;
 	cd->mair	= pgtbl_cfg->arm_lpae_s1_cfg.mair;
 
-	ret = arm_smmu_write_ctx_desc(master, 0, cd);
-	if (ret)
-		goto out_free_cd_tables;
-
 	mutex_unlock(&arm_smmu_asid_lock);
 	return 0;
 
-out_free_cd_tables:
-	arm_smmu_free_cd_tables(smmu_domain);
-out_free_asid:
-	arm_smmu_free_asid(cd);
 out_unlock:
 	mutex_unlock(&arm_smmu_asid_lock);
 	return ret;
@@ -2400,6 +2383,14 @@ static void arm_smmu_detach_dev(struct arm_smmu_master *master)
 	master->domain = NULL;
 	master->ats_enabled = false;
 	arm_smmu_install_ste_for_dev(master);
+	/*
+	 * Clearing the CD entry isn't strictly required to detach the domain
+	 * since the table is uninstalled anyway, but it helps avoid confusion
+	 * in the call to arm_smmu_write_ctx_desc on the next attach (which
+	 * expects the entry to be empty).
+	 */
+	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 && master->cd_table.cdtab)
+		arm_smmu_write_ctx_desc(master, 0, NULL);
 }
 
 static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
@@ -2434,23 +2425,14 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	if (!smmu_domain->smmu) {
 		smmu_domain->smmu = smmu;
 		ret = arm_smmu_domain_finalise(domain, master);
-		if (ret) {
+		if (ret)
 			smmu_domain->smmu = NULL;
-			goto out_unlock;
-		}
-	} else if (smmu_domain->smmu != smmu) {
-		ret = -EINVAL;
-		goto out_unlock;
-	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
-		   master->ssid_bits != smmu_domain->cd_table.s1cdmax) {
+	} else if (smmu_domain->smmu != smmu)
 		ret = -EINVAL;
-		goto out_unlock;
-	} else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1 &&
-		   smmu_domain->cd_table.stall_enabled !=
-			   master->stall_enabled) {
-		ret = -EINVAL;
-		goto out_unlock;
-	}
+
+	mutex_unlock(&smmu_domain->init_mutex);
+	if (ret)
+		return ret;
 
 	master->domain = smmu_domain;
 
@@ -2464,16 +2446,42 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev)
 	if (smmu_domain->stage != ARM_SMMU_DOMAIN_BYPASS)
 		master->ats_enabled = arm_smmu_ats_supported(master);
 
-	arm_smmu_install_ste_for_dev(master);
-
 	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
 	list_add(&master->domain_head, &smmu_domain->devices);
 	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
 
+	if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
+		if (!master->cd_table.cdtab) {
+			ret = arm_smmu_alloc_cd_tables(master);
+			if (ret) {
+				master->domain = NULL;
+				goto out_list_del;
+			}
+		}
+
+		/*
+		 * Prevent SVA from concurrently modifying the CD or writing to
+		 * the CD entry
+		 */
+		mutex_lock(&arm_smmu_asid_lock);
+		ret = arm_smmu_write_ctx_desc(master, 0, &smmu_domain->cd);
+		mutex_unlock(&arm_smmu_asid_lock);
+		if (ret) {
+			master->domain = NULL;
+			goto out_list_del;
+		}
+	}
+
+	arm_smmu_install_ste_for_dev(master);
+
 	arm_smmu_enable_ats(master);
+	return 0;
+
+out_list_del:
+	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
+	list_del(&master->domain_head);
+	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
 
-out_unlock:
-	mutex_unlock(&smmu_domain->init_mutex);
 	return ret;
 }
 
@@ -2718,6 +2726,8 @@ static void arm_smmu_release_device(struct device *dev)
 	arm_smmu_detach_dev(master);
 	arm_smmu_disable_pasid(master);
 	arm_smmu_remove_master(master);
+	if (master->cd_table.cdtab)
+		arm_smmu_free_cd_tables(master);
 	kfree(master);
 }
 
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 00f8e6388848e..2f4b832e0deb4 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -695,6 +695,8 @@ struct arm_smmu_master {
 	struct arm_smmu_domain		*domain;
 	struct list_head		domain_head;
 	struct arm_smmu_stream		*streams;
+	/* Locked by the iommu core using the group mutex */
+	struct arm_smmu_ctx_desc_cfg	cd_table;
 	unsigned int			num_streams;
 	bool				ats_enabled;
 	bool				stall_enabled;
@@ -721,11 +723,8 @@ struct arm_smmu_domain {
 
 	enum arm_smmu_domain_stage	stage;
 	union {
-		struct {
 		struct arm_smmu_ctx_desc	cd;
-		struct arm_smmu_ctx_desc_cfg	cd_table;
-		};
-		struct arm_smmu_s2_cfg	s2_cfg;
+		struct arm_smmu_s2_cfg		s2_cfg;
 	};
 
 	struct iommu_domain		domain;
-- 
2.42.0.283.g2d96d420d3-goog