Re: [PATCH v5 1/9] iommu/arm-smmu-v3: Handle ARM erratum for CONT under invalidation with SVA

The erratum (MMU-700: #3777127, S3: #3673557) deals with under
invalidation of a CONT PTE grouping in the SMMU. The recommended work
around is to use a Range Invalidate (RIL) that spans the entire CONT. The
only user of CONT in the kernel right now is through SVA sharing a CPU
page table that contains a CONT created by the mm.

Previously it was thought that this errata was dealt with because the
driver always uses RIL. However, there is a subtle detail in the errata
that the RIL range must fully enclose the entire CONT for it to work.

It seems that two sequential RILs, with a split point falling inside a
CONT grouping, will not prevent the errata.

The SMMU's RIL generation algorithm does not produce a single RIL for a
single SVA invalidation request, nor does the mm carefully align the SVA
invalidation ranges to accommodate the RIL splitting.

Thus, when processing a SVA invalidation, the RIL splitting routine can
generate a RIL that is split in the middle of the CONT and risk under
invalidation from this errata. This condition could be triggered by a
malicious userspace manipulating the TLB gathers via mmap/mprotect/munmap.

Update the errata list to the include the S3 variation, detect the IOMMUs
that have it, and then have SVA invalidations use a simplified version of
the over invalidation algorithm from the tlbi rework series. This ensures
that a single RIL is issued for a single MMU notifier callback and now the
RIL is guarenteed to cover any posible CONT.

Future work to add CONT to iommu_domain page tables should either use this
one-invalidate/one-RIL algorithm or disable CONT support in the
iommu_domain.

Cc: stable@vger.kernel.org
Fixes: 3f1ce8e85ee0 ("iommu/arm-smmu-v3: Share process page tables")
Cc: Vijayanand Jitta <redacted>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
---
 Documentation/arch/arm64/silicon-errata.rst   |  3 +-
 .../iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c   |  7 ++
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   | 87 +++++++++++++++----
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  2 +
 4 files changed, 81 insertions(+), 18 deletions(-)

diff --git a/Documentation/arch/arm64/silicon-errata.rst b/Documentation/arch/arm64/silicon-errata.rst
index ac3248b9f2f3bb..68018bf75b7910 100644
--- a/Documentation/arch/arm64/silicon-errata.rst
+++ b/Documentation/arch/arm64/silicon-errata.rst

@@ -271,7 +271,8 @@ stable kernels.
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | MMU L1          | #3878312        | N/A                         |
 +----------------+-----------------+-----------------+-----------------------------+
-| ARM            | MMU S3          | #3995052        | N/A                         |
+| ARM            | MMU S3          | #3995052,       | N/A                         |
+|                |                 | #3673557        |                             |
 +----------------+-----------------+-----------------+-----------------------------+
 | ARM            | GIC-700         | #2941627        | ARM64_ERRATUM_2941627       |
 +----------------+-----------------+-----------------+-----------------------------+

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 0a429c64fbf3e7..a0c9078646fb55 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

@@ -215,6 +215,13 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
 	if (system_supports_haft())
 		feat_mask |= ARM_SMMU_FEAT_HAFT;
 
+	/*
+	 * The workaround for ARM_SMMU_OPT_FULL_CONT_RIL requires range
+	 * invalidation support.
+	 */
+	if (smmu->options & ARM_SMMU_OPT_FULL_CONT_RIL)
+		feat_mask |= ARM_SMMU_FEAT_RANGE_INV;
+
 	if ((smmu->features & feat_mask) != feat_mask)
 		return false;
 

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 5732f3ba0122d6..d6896e25b6632a 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -2538,6 +2538,36 @@ static void arm_smmu_cmdq_batch_add_range(struct arm_smmu_device *smmu,
 	}
 }
 
+/*
+ * Generate a RIL for ARM_SMMU_OPT_FULL_CONT_RIL by ensuring the entire SVA
+ * requested range is covered with a single RIL command. The scale is adjusted
+ * so that the RIL may extend past the end of the requested range. This ensures
+ * that any CONT the MM is invalidating is covered by a single RIL. TTL and LEAF
+ * are always 0 because this is only used by SVA.
+ */
+static bool arm_smmu_cmdq_batch_add_ril(struct arm_smmu_device *smmu,
+					struct arm_smmu_cmdq_batch *cmds,
+					struct arm_smmu_cmd *cmd,
+					unsigned long iova, size_t size,
+					u8 tgsz_lg2)
+{
+	u64 cur_tg = iova >> tgsz_lg2;

+	u64 num_tg = ((iova + size - 1) >> tgsz_lg2) - cur_tg + 1;
+	unsigned int scale = fls64((num_tg - 1) / 32);
+
+	if (scale > 31)
+		return false;
+
+	cmd->data[0] |=
+		FIELD_PREP(CMDQ_TLBI_0_NUM,
+			   DIV_ROUND_UP_ULL(num_tg, 1ULL << scale) - 1) |
+		FIELD_PREP(CMDQ_TLBI_0_SCALE, scale);
+	cmd->data[1] = FIELD_PREP(CMDQ_TLBI_1_TG, (tgsz_lg2 - 10) / 2) |
+		       (cur_tg << tgsz_lg2);
+	arm_smmu_cmdq_batch_add_cmd_p(smmu, cmds, cmd);
+	return true;
+}
+
 static bool arm_smmu_inv_size_too_big(struct arm_smmu_device *smmu, size_t size,
 				      size_t granule)
 {

@@ -2565,21 +2595,30 @@ static bool arm_smmu_inv_size_too_big(struct arm_smmu_device *smmu, size_t size,
 static void arm_smmu_inv_to_cmdq_batch(struct arm_smmu_inv *inv,
 				       struct arm_smmu_cmdq_batch *cmds,
 				       struct arm_smmu_cmd *cmd,
-				       bool leaf,
+				       bool single_ril, bool leaf,
 				       unsigned long iova, size_t size,
 				       unsigned int granule)
 {
-	if (arm_smmu_inv_size_too_big(inv->smmu, size, granule)) {
-		struct arm_smmu_cmd nsize_cmd = *cmd;
+	struct arm_smmu_cmd nsize_cmd;
 
-		u64p_replace_bits(&nsize_cmd.data[0], inv->nsize_opcode,
-				  CMDQ_0_OP);
-		arm_smmu_cmdq_batch_add_cmd_p(inv->smmu, cmds, &nsize_cmd);
+	if (arm_smmu_inv_size_too_big(inv->smmu, size, granule))
+		goto full_inv;
+
+	if (single_ril && size > granule) {
+		if (!arm_smmu_cmdq_batch_add_ril(inv->smmu, cmds, cmd, iova,
+						 size, inv->pgsize))
+			goto full_inv;
 		return;
 	}
 
-	arm_smmu_cmdq_batch_add_range(inv->smmu, cmds, cmd, leaf,
-				      iova, size, granule, inv->pgsize);
+	arm_smmu_cmdq_batch_add_range(inv->smmu, cmds, cmd, leaf, iova, size,
+				      granule, inv->pgsize);
+	return;
+
+full_inv:
+	nsize_cmd = *cmd;
+	u64p_replace_bits(&nsize_cmd.data[0], inv->nsize_opcode, CMDQ_0_OP);
+	arm_smmu_cmdq_batch_add_cmd_p(inv->smmu, cmds, &nsize_cmd);
 }
 
 static inline bool arm_smmu_invs_end_batch(struct arm_smmu_inv *cur,

@@ -2600,7 +2639,8 @@ static inline bool arm_smmu_invs_end_batch(struct arm_smmu_inv *cur,
 
 static void __arm_smmu_domain_inv_range(struct arm_smmu_invs *invs,
 					unsigned long iova, size_t size,
-					unsigned int granule, bool leaf)
+					unsigned int granule, bool single_ril,
+					bool leaf)
 {
 	struct arm_smmu_cmdq_batch cmds = {};
 	struct arm_smmu_inv *cur;

@@ -2630,14 +2670,14 @@ static void __arm_smmu_domain_inv_range(struct arm_smmu_invs *invs,
 		case INV_TYPE_S1_ASID:
 			cmd = arm_smmu_make_cmd_tlbi(cur->size_opcode,
 						     cur->id, 0);
-			arm_smmu_inv_to_cmdq_batch(cur, &cmds, &cmd, leaf,
-						   iova, size, granule);
+			arm_smmu_inv_to_cmdq_batch(cur, &cmds, &cmd, single_ril,
+						   leaf, iova, size, granule);
 			break;
 		case INV_TYPE_S2_VMID:
 			cmd = arm_smmu_make_cmd_tlbi(cur->size_opcode,
 						     0, cur->id);
-			arm_smmu_inv_to_cmdq_batch(cur, &cmds, &cmd, leaf,
-						   iova, size, granule);
+			arm_smmu_inv_to_cmdq_batch(cur, &cmds, &cmd, single_ril,
+						   leaf, iova, size, granule);
 			break;
 		case INV_TYPE_S2_VMID_S1_CLEAR:
 			/* CMDQ_OP_TLBI_S12_VMALL already flushed S1 entries */

@@ -2684,6 +2724,9 @@ void arm_smmu_domain_inv_range(struct arm_smmu_domain *smmu_domain,
 			       unsigned int granule, bool leaf)
 {
 	struct arm_smmu_invs *invs;
+	bool single_ril =
+		smmu_domain->stage == ARM_SMMU_DOMAIN_SVA &&
+		(smmu_domain->smmu->options & ARM_SMMU_OPT_FULL_CONT_RIL);
 
 	/*
 	 * An invalidation request must follow some IOPTE change and then load

@@ -2723,10 +2766,12 @@ void arm_smmu_domain_inv_range(struct arm_smmu_domain *smmu_domain,
 		unsigned long flags;
 
 		read_lock_irqsave(&invs->rwlock, flags);
-		__arm_smmu_domain_inv_range(invs, iova, size, granule, leaf);
+		__arm_smmu_domain_inv_range(invs, iova, size, granule,
+					    single_ril, leaf);
 		read_unlock_irqrestore(&invs->rwlock, flags);
 	} else {
-		__arm_smmu_domain_inv_range(invs, iova, size, granule, leaf);
+		__arm_smmu_domain_inv_range(invs, iova, size, granule,
+					    single_ril, leaf);
 	}
 
 	rcu_read_unlock();

@@ -5009,12 +5054,20 @@ static void arm_smmu_device_iidr_probe(struct arm_smmu_device *smmu)
 				/* Arm errata 2268618, 2812531 */
 				smmu->features &= ~ARM_SMMU_FEAT_NESTING;
 			}
+			/* Arm errata 3777127 */
+			smmu->options |= ARM_SMMU_OPT_FULL_CONT_RIL;
 			break;
 		case IIDR_PRODUCTID_ARM_MMU_L1:
-		case IIDR_PRODUCTID_ARM_MMU_S3:
-			/* Arm errata 3878312/3995052 */
+			/* Arm errata 3878312 */
 			smmu->features &= ~ARM_SMMU_FEAT_BTM;
 			break;
+		case IIDR_PRODUCTID_ARM_MMU_S3:
+			/* Arm errata 3995052 */
+			smmu->features &= ~ARM_SMMU_FEAT_BTM;
+			/* Arm errata 3673557 */
+			if (variant < 1 || (variant == 1 && revision < 1))
+				smmu->options |= ARM_SMMU_OPT_FULL_CONT_RIL;
+			break;
 		}
 		break;
 	}

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 50f8321e979cef..065d76eb148119 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -934,6 +934,8 @@ struct arm_smmu_device {
 #define ARM_SMMU_OPT_MSIPOLL		(1 << 2)
 #define ARM_SMMU_OPT_CMDQ_FORCE_SYNC	(1 << 3)
 #define ARM_SMMU_OPT_TEGRA241_CMDQV	(1 << 4)
+/* RANGE_INV is mandatory and one RIL must fully span an invalidated CONT */
+#define ARM_SMMU_OPT_FULL_CONT_RIL	(1 << 5)
 	u32				options;
 
 	struct arm_smmu_cmdq		cmdq;

-- 
2.43.0