iommu/arm-smmu-v3: Start a new batch if new command is not supported

The VCMDQ in the tegra241-cmdqv driver has a guest mode that supports only
a few invalidation commands. A batch is initialized with a cmdq, so it has
to confirm whether a new command is supported or not.

Add a supports_cmd function pointer to the cmdq structure, where the vcmdq
driver should hook a command scan function. Add an inline helper too so it
can be used by both sides.

If a new command is not supported, simply issue the existing batch and re-
init it as a new batch.

Signed-off-by: Nicolin Chen <[email protected]>
Link: https://lore.kernel.org/r/aafb24b881504f18c5d0c7c15f2134e40ad2c486.1724970714.git.nicolinc@nvidia.com
Signed-off-by: Will Deacon <[email protected]>

Author: nicolinc

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c

@@ -923,10 +923,12 @@ static void arm_smmu_cmdq_batch_add(struct arm_smmu_device *smmu,
 				    struct arm_smmu_cmdq_batch *cmds,
 				    struct arm_smmu_cmdq_ent *cmd)
 {
+	bool unsupported_cmd = !arm_smmu_cmdq_supports_cmd(cmds->cmdq, cmd);
+	bool force_sync = (cmds->num == CMDQ_BATCH_ENTRIES - 1) &&
+			  (smmu->options & ARM_SMMU_OPT_CMDQ_FORCE_SYNC);
 	int index;
 
-	if (cmds->num == CMDQ_BATCH_ENTRIES - 1 &&
-	    (smmu->options & ARM_SMMU_OPT_CMDQ_FORCE_SYNC)) {
+	if (force_sync || unsupported_cmd) {
 		arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmdq, cmds->cmds,
 					    cmds->num, true);
 		arm_smmu_cmdq_batch_init(smmu, cmds);

drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h

@@ -568,8 +568,15 @@ struct arm_smmu_cmdq {
 	atomic_long_t			*valid_map;
 	atomic_t			owner_prod;
 	atomic_t			lock;
+	bool				(*supports_cmd)(struct arm_smmu_cmdq_ent *ent);
 };
 
+static inline bool arm_smmu_cmdq_supports_cmd(struct arm_smmu_cmdq *cmdq,
+					      struct arm_smmu_cmdq_ent *ent)
+{
+	return cmdq->supports_cmd ? cmdq->supports_cmd(ent) : true;
+}
+
 struct arm_smmu_cmdq_batch {
 	u64				cmds[CMDQ_BATCH_ENTRIES * CMDQ_ENT_DWORDS];
 	struct arm_smmu_cmdq		*cmdq;