Re: [PATCH v2] iommu/arm-smmu-v3: Batch ATC invalidation commands

[Jean-Philippe Brucker <jean-philippe@linaro.org>]

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On Thu, Feb 13, 2020 at 02:56:00PM -0600, Rob Herring wrote:
> Similar to commit 2af2e72b18b4 ("iommu/arm-smmu-v3: Defer TLB
> invalidation until ->iotlb_sync()"), build up a list of ATC invalidation
> commands and submit them all at once to the command queue instead of
> one-by-one.
> 
> As there is only one caller of arm_smmu_atc_inv_master() left, we can
> simplify it and avoid passing in struct arm_smmu_cmdq_ent.
> 
> Cc: Jean-Philippe Brucker <jean-philippe@linaro.org>
> Cc: Will Deacon <will@kernel.org>
> Cc: Robin Murphy <robin.murphy@arm.com>
> Cc: Joerg Roedel <joro@8bytes.org>
> Signed-off-by: Rob Herring <robh@kernel.org>

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>


Since I'm adding a third user of cmdq batching [1], I had a go at
factoring them. I can send the attached patch with my next version, if it
looks OK.

Thanks,
Jean

[1] https://lore.kernel.org/linux-iommu/20200213101435.229932-4-jean-philippe@linaro.org/


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From b304f322e6293be4ec8b5a01e2ef67e8fa34143c Mon Sep 17 00:00:00 2001
From: Jean-Philippe Brucker <jean-philippe@linaro.org>
Date: Mon, 17 Feb 2020 17:42:54 +0100
Subject: [PATCH] iommu/arm-smmu-v3: Factor command queue batching

Factor the code for command queue batching, which is now repeated three
times for TLB, ATC and CFG invalidations.

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
 drivers/iommu/arm-smmu-v3.c | 66 +++++++++++++++++++------------------
 1 file changed, 34 insertions(+), 32 deletions(-)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 45da5c251b65..04c3077589be 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -548,6 +548,11 @@ struct arm_smmu_cmdq {
 	atomic_t			lock;
 };
 
+struct arm_smmu_cmdq_batch {
+	u64				cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
+	int				num;
+};
+
 struct arm_smmu_evtq {
 	struct arm_smmu_queue		q;
 	u32				max_stalls;
@@ -1482,15 +1487,33 @@ static int arm_smmu_cmdq_issue_sync(struct arm_smmu_device *smmu)
 	return arm_smmu_cmdq_issue_cmdlist(smmu, NULL, 0, true);
 }
 
+static void arm_smmu_cmdq_batch_add(struct arm_smmu_device *smmu,
+				    struct arm_smmu_cmdq_batch *cmds,
+				    struct arm_smmu_cmdq_ent *cmd)
+{
+	if (cmds->num == CMDQ_BATCH_ENTRIES) {
+		arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, false);
+		cmds->num = 0;
+	}
+	arm_smmu_cmdq_build_cmd(&cmds->cmds[cmds->num * CMDQ_ENT_DWORDS], cmd);
+	cmds->num++;
+}
+
+static int arm_smmu_cmdq_batch_submit(struct arm_smmu_device *smmu,
+				      struct arm_smmu_cmdq_batch *cmds)
+{
+	return arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, true);
+}
+
+
 /* Context descriptor manipulation functions */
 static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
 			     int ssid, bool leaf)
 {
 	size_t i;
-	int cmdn = 0;
 	unsigned long flags;
 	struct arm_smmu_master *master;
-	u64 cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
+	struct arm_smmu_cmdq_batch cmds = {};
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	struct arm_smmu_cmdq_ent cmd = {
 		.opcode	= CMDQ_OP_CFGI_CD,
@@ -1503,19 +1526,13 @@ static void arm_smmu_sync_cd(struct arm_smmu_domain *smmu_domain,
 	spin_lock_irqsave(&smmu_domain->devices_lock, flags);
 	list_for_each_entry(master, &smmu_domain->devices, domain_head) {
 		for (i = 0; i < master->num_sids; i++) {
-			if (cmdn == CMDQ_BATCH_ENTRIES) {
-				arm_smmu_cmdq_issue_cmdlist(smmu, cmds, cmdn, false);
-				cmdn = 0;
-			}
-
 			cmd.cfgi.sid = master->sids[i];
-			arm_smmu_cmdq_build_cmd(&cmds[cmdn * CMDQ_ENT_DWORDS], &cmd);
-			cmdn++;
+			arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
 		}
 	}
 	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
 
-	arm_smmu_cmdq_issue_cmdlist(smmu, cmds, cmdn, true);
+	arm_smmu_cmdq_batch_submit(smmu, &cmds);
 }
 
 static int arm_smmu_alloc_cd_leaf_table(struct arm_smmu_device *smmu,
@@ -2160,11 +2177,11 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master)
 static int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain,
 				   int ssid, unsigned long iova, size_t size)
 {
-	int i, cmdn = 0;
+	int i;
 	unsigned long flags;
 	struct arm_smmu_cmdq_ent cmd;
 	struct arm_smmu_master *master;
-	u64 cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
+	struct arm_smmu_cmdq_batch cmds = {};
 
 	if (!(smmu_domain->smmu->features & ARM_SMMU_FEAT_ATS))
 		return 0;
@@ -2194,20 +2211,13 @@ static int arm_smmu_atc_inv_domain(struct arm_smmu_domain *smmu_domain,
 			continue;
 
 		for (i = 0; i < master->num_sids; i++) {
-			if (cmdn == CMDQ_BATCH_ENTRIES) {
-				arm_smmu_cmdq_issue_cmdlist(smmu_domain->smmu,
-					cmds, cmdn, false);
-				cmdn = 0;
-			}
-
 			cmd.atc.sid = master->sids[i];
-			arm_smmu_cmdq_build_cmd(&cmds[cmdn * CMDQ_ENT_DWORDS], &cmd);
-			cmdn++;
+			arm_smmu_cmdq_batch_add(smmu_domain->smmu, &cmds, &cmd);
 		}
 	}
 	spin_unlock_irqrestore(&smmu_domain->devices_lock, flags);
 
-	return arm_smmu_cmdq_issue_cmdlist(smmu_domain->smmu, cmds, cmdn, true);
+	return arm_smmu_cmdq_batch_submit(smmu_domain->smmu, &cmds);
 }
 
 /* IO_PGTABLE API */
@@ -2242,10 +2252,9 @@ static void arm_smmu_tlb_inv_range(unsigned long iova, size_t size,
 				   size_t granule, bool leaf,
 				   struct arm_smmu_domain *smmu_domain)
 {
-	u64 cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
 	unsigned long start = iova, end = iova + size;
-	int i = 0;
+	struct arm_smmu_cmdq_batch cmds = {};
 	struct arm_smmu_cmdq_ent cmd = {
 		.tlbi = {
 			.leaf	= leaf,
@@ -2264,18 +2273,11 @@ static void arm_smmu_tlb_inv_range(unsigned long iova, size_t size,
 	}
 
 	while (iova < end) {
-		if (i == CMDQ_BATCH_ENTRIES) {
-			arm_smmu_cmdq_issue_cmdlist(smmu, cmds, i, false);
-			i = 0;
-		}
-
 		cmd.tlbi.addr = iova;
-		arm_smmu_cmdq_build_cmd(&cmds[i * CMDQ_ENT_DWORDS], &cmd);
+		arm_smmu_cmdq_batch_add(smmu, &cmds, &cmd);
 		iova += granule;
-		i++;
 	}
-
-	arm_smmu_cmdq_issue_cmdlist(smmu, cmds, i, true);
+	arm_smmu_cmdq_batch_submit(smmu, &cmds);
 
 	/*
 	 * Unfortunately, this can't be leaf-only since we may have
-- 
2.25.0


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