Calculate the batch size limit such that all CPUs in the system cannot
issue so many commands as to fill the command queue.
Signed-off-by: John Garry <john.ga...@huawei.com>
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 46 +++++++++++++++++++--
1 file changed, 42 insertions(+), 4 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 7196207be7ea..a705fa3e18ea 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -532,6 +532,7 @@ struct arm_smmu_ll_queue {
u8 __pad[SMP_CACHE_BYTES];
} ____cacheline_aligned_in_smp;
u32 max_n_shift;
+ u32 max_cmd_per_batch;
};
struct arm_smmu_queue {
@@ -1515,7 +1516,10 @@ 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) {
+ struct arm_smmu_cmdq *q = &smmu->cmdq;
+ struct arm_smmu_ll_queue *llq = &q->q.llq;
+
+ if (cmds->num == llq->max_cmd_per_batch) {
arm_smmu_cmdq_issue_cmdlist(smmu, cmds->cmds, cmds->num, false);
cmds->num = 0;
}
@@ -3177,6 +3181,41 @@ static int arm_smmu_init_one_queue(struct
arm_smmu_device *smmu,
return 0;
}
+static int arm_smmu_init_cmd_queue(struct arm_smmu_device *smmu,
+ struct arm_smmu_queue *q,
+ unsigned long prod_off,
+ unsigned long cons_off,
+ size_t dwords)
+{
+ u32 cpus = num_possible_cpus(), entries_for_prod;
+ int ret;
+
+ ret = arm_smmu_init_one_queue(smmu, q, prod_off, cons_off, dwords,
+ "cmdq");
+ if (ret)
+ return ret;
+
+ entries_for_prod = 1 << q->llq.max_n_shift;
+
+ /*
+ * We need at least 2 commands in a batch (1 x CMD_SYNC and 1 x
+ * whatever else).
+ */
+ if (entries_for_prod < 2 * cpus) {
+ dev_err(smmu->dev, "command queue size too small, suggest
reduce #CPUs\n");
+ return -ENXIO;
+ }
+
+ /*
+ * When finding max_cmd_per_batch, deduct 1 entry per batch to take
+ * account of a CMD_SYNC being issued also.
+ */
+ q->llq.max_cmd_per_batch = min((entries_for_prod / cpus) - 1,
+ (u32)CMDQ_BATCH_ENTRIES);
+
+ return 0;
+}
+
static void arm_smmu_cmdq_free_bitmap(void *data)
{
unsigned long *bitmap = data;
@@ -3210,9 +3249,8 @@ static int arm_smmu_init_queues(struct arm_smmu_device
*smmu)
int ret;
/* cmdq */
- ret = arm_smmu_init_one_queue(smmu, &smmu->cmdq.q, ARM_SMMU_CMDQ_PROD,
- ARM_SMMU_CMDQ_CONS, CMDQ_ENT_DWORDS,
- "cmdq");
+ ret = arm_smmu_init_cmd_queue(smmu, &smmu->cmdq.q, ARM_SMMU_CMDQ_PROD,
+ ARM_SMMU_CMDQ_CONS, CMDQ_ENT_DWORDS);
if (ret)
return ret;
--
2.26.2
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