iommu/arm-smmu-v3: Specialise CMD_SYNC handling

CMD_SYNC already has a bit of special treatment here and there, but as
we're about to extend it with more functionality for completing outside
the CMDQ lock, things are going to get rather messy if we keep trying to
cram everything into a single generic command interface. Instead, let's
break out the issuing of CMD_SYNC into its own specific helper where
upcoming changes will have room to breathe.

Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/arm-smmu-v3.c

@@ -929,13 +929,22 @@ static void arm_smmu_cmdq_skip_err(struct arm_smmu_device *smmu)
 	queue_write(Q_ENT(q, cons), cmd, q->ent_dwords);
 }
 
+static void arm_smmu_cmdq_insert_cmd(struct arm_smmu_device *smmu, u64 *cmd)
+{
+	struct arm_smmu_queue *q = &smmu->cmdq.q;
+	bool wfe = !!(smmu->features & ARM_SMMU_FEAT_SEV);
+
+	while (queue_insert_raw(q, cmd) == -ENOSPC) {
+		if (queue_poll_cons(q, false, wfe))
+			dev_err_ratelimited(smmu->dev, "CMDQ timeout\n");
+	}
+}
+
 static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
 				    struct arm_smmu_cmdq_ent *ent)
 {
 	u64 cmd[CMDQ_ENT_DWORDS];
 	unsigned long flags;
-	bool wfe = !!(smmu->features & ARM_SMMU_FEAT_SEV);
-	struct arm_smmu_queue *q = &smmu->cmdq.q;
 
 	if (arm_smmu_cmdq_build_cmd(cmd, ent)) {
 		dev_warn(smmu->dev, "ignoring unknown CMDQ opcode 0x%x\n",
@@ -944,14 +953,27 @@ static void arm_smmu_cmdq_issue_cmd(struct arm_smmu_device *smmu,
 	}
 
 	spin_lock_irqsave(&smmu->cmdq.lock, flags);
-	while (queue_insert_raw(q, cmd) == -ENOSPC) {
-		if (queue_poll_cons(q, false, wfe))
-			dev_err_ratelimited(smmu->dev, "CMDQ timeout\n");
-	}
+	arm_smmu_cmdq_insert_cmd(smmu, cmd);
+	spin_unlock_irqrestore(&smmu->cmdq.lock, flags);
+}
 
-	if (ent->opcode == CMDQ_OP_CMD_SYNC && queue_poll_cons(q, true, wfe))
-		dev_err_ratelimited(smmu->dev, "CMD_SYNC timeout\n");
+static void arm_smmu_cmdq_issue_sync(struct arm_smmu_device *smmu)
+{
+	u64 cmd[CMDQ_ENT_DWORDS];
+	unsigned long flags;
+	bool wfe = !!(smmu->features & ARM_SMMU_FEAT_SEV);
+	struct arm_smmu_cmdq_ent ent = { .opcode = CMDQ_OP_CMD_SYNC };
+	int ret;
+
+	arm_smmu_cmdq_build_cmd(cmd, &ent);
+
+	spin_lock_irqsave(&smmu->cmdq.lock, flags);
+	arm_smmu_cmdq_insert_cmd(smmu, cmd);
+	ret = queue_poll_cons(&smmu->cmdq.q, true, wfe);
 	spin_unlock_irqrestore(&smmu->cmdq.lock, flags);
+
+	if (ret)
+		dev_err_ratelimited(smmu->dev, "CMD_SYNC timeout\n");
 }
 
 /* Context descriptor manipulation functions */
@@ -1027,8 +1049,7 @@ static void arm_smmu_sync_ste_for_sid(struct arm_smmu_device *smmu, u32 sid)
 	};
 
 	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
-	cmd.opcode = CMDQ_OP_CMD_SYNC;
-	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
+	arm_smmu_cmdq_issue_sync(smmu);
 }
 
 static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
@@ -1355,10 +1376,7 @@ static irqreturn_t arm_smmu_combined_irq_handler(int irq, void *dev)
 /* IO_PGTABLE API */
 static void __arm_smmu_tlb_sync(struct arm_smmu_device *smmu)
 {
-	struct arm_smmu_cmdq_ent cmd;
-
-	cmd.opcode = CMDQ_OP_CMD_SYNC;
-	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
+	arm_smmu_cmdq_issue_sync(smmu);
 }
 
 static void arm_smmu_tlb_sync(void *cookie)
@@ -2402,8 +2420,7 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
 	/* Invalidate any cached configuration */
 	cmd.opcode = CMDQ_OP_CFGI_ALL;
 	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
-	cmd.opcode = CMDQ_OP_CMD_SYNC;
-	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
+	arm_smmu_cmdq_issue_sync(smmu);
 
 	/* Invalidate any stale TLB entries */
 	if (smmu->features & ARM_SMMU_FEAT_HYP) {
@@ -2413,8 +2430,7 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
 
 	cmd.opcode = CMDQ_OP_TLBI_NSNH_ALL;
 	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
-	cmd.opcode = CMDQ_OP_CMD_SYNC;
-	arm_smmu_cmdq_issue_cmd(smmu, &cmd);
+	arm_smmu_cmdq_issue_sync(smmu);
 
 	/* Event queue */
 	writeq_relaxed(smmu->evtq.q.q_base, smmu->base + ARM_SMMU_EVTQ_BASE);