[PATCH v5 20/27] iommu/arm-smmu-v3-kvm: Add CMDQ functions

[Mostafa Saleh <smostafa@google.com>]

Add functions to access the command queue, there are 2 main usage:
- Hypervisor's own commands, as TLB invalidation, would use functions
  as smmu_send_cmd(), which creates and sends a command.
- Add host commands to the shadow command queue, after being filtered,
  these will be added with smmu_add_cmd_raw.

Signed-off-by: Mostafa Saleh <smostafa@google.com>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  14 +--
 .../iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c  | 102 ++++++++++++++++++
 2 files changed, 110 insertions(+), 6 deletions(-)

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 1d552efdc4ae..d909014baad3 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -1015,19 +1015,21 @@ int arm_smmu_cmdq_issue_cmdlist(struct arm_smmu_device *smmu,
 int arm_smmu_cmdq_build_cmd(u64 *cmd, struct arm_smmu_cmdq_ent *ent);
 
 /* Queue functions shared between kernel and hyp. */
-static inline bool queue_has_space(struct arm_smmu_ll_queue *q, u32 n)
+static inline u32 queue_space(struct arm_smmu_ll_queue *q)
 {
-	u32 space, prod, cons;
+	u32 prod, cons;
 
 	prod = Q_IDX(q, q->prod);
 	cons = Q_IDX(q, q->cons);
 
 	if (Q_WRP(q, q->prod) == Q_WRP(q, q->cons))
-		space = (1 << q->max_n_shift) - (prod - cons);
-	else
-		space = cons - prod;
+		return (1 << q->max_n_shift) - (prod - cons);
+	return cons - prod;
+}
 
-	return space >= n;
+static inline bool queue_has_space(struct arm_smmu_ll_queue *q, u32 n)
+{
+	return queue_space(q) >= n;
 }
 
 static inline bool queue_full(struct arm_smmu_ll_queue *q)
diff --git a/drivers/iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c
index bcb3f99fdcd2..a970b43e6a7e 100644
--- a/drivers/iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c
@@ -22,6 +22,26 @@ struct hyp_arm_smmu_v3_device *kvm_hyp_arm_smmu_v3_smmus;
 
 #define cmdq_size(cmdq)	((1 << ((cmdq)->llq.max_n_shift)) * CMDQ_ENT_DWORDS * 8)
 
+/*
+ * Wait until @cond is true.
+ * Return 0 on success, or -ETIMEDOUT
+ */
+#define smmu_wait(use_wfe, _cond)					\
+({								\
+	int __ret = 0;						\
+	u64 delay = pkvm_time_get() + ARM_SMMU_POLL_TIMEOUT_US;	\
+								\
+	while (!(_cond)) {					\
+		if (use_wfe)					\
+			wfe();					\
+		if (pkvm_time_get() >= delay) {			\
+			__ret = -ETIMEDOUT;			\
+			break;					\
+		}						\
+	}							\
+	__ret;							\
+})
+
 static bool is_cmdq_enabled(struct hyp_arm_smmu_v3_device *smmu)
 {
 	return FIELD_GET(CR0_CMDQEN, smmu->cr0);
@@ -69,6 +89,88 @@ static int smmu_unshare_pages(phys_addr_t addr, size_t size)
 	return 0;
 }
 
+__maybe_unused
+static bool smmu_cmdq_has_space(struct arm_smmu_queue *cmdq, u32 n)
+{
+	struct arm_smmu_ll_queue *llq = &cmdq->llq;
+
+	WRITE_ONCE(llq->cons, readl_relaxed(cmdq->cons_reg));
+	return queue_has_space(llq, n);
+}
+
+static bool smmu_cmdq_full(struct arm_smmu_queue *cmdq)
+{
+	struct arm_smmu_ll_queue *llq = &cmdq->llq;
+
+	WRITE_ONCE(llq->cons, readl_relaxed(cmdq->cons_reg));
+	return queue_full(llq);
+}
+
+static bool smmu_cmdq_empty(struct arm_smmu_queue *cmdq)
+{
+	struct arm_smmu_ll_queue *llq = &cmdq->llq;
+
+	WRITE_ONCE(llq->cons, readl_relaxed(cmdq->cons_reg));
+	return queue_empty(llq);
+}
+
+static void smmu_add_cmd_raw(struct hyp_arm_smmu_v3_device *smmu,
+			     u64 *cmd)
+{
+	struct arm_smmu_queue *q = &smmu->cmdq;
+	struct arm_smmu_ll_queue *llq = &q->llq;
+
+	queue_write(Q_ENT(q, llq->prod), cmd,  CMDQ_ENT_DWORDS);
+	llq->prod = queue_inc_prod_n(llq, 1);
+}
+
+static int smmu_add_cmd(struct hyp_arm_smmu_v3_device *smmu,
+			struct arm_smmu_cmdq_ent *ent)
+{
+	int ret;
+	u64 cmd[CMDQ_ENT_DWORDS];
+
+	ret = smmu_wait(smmu->features & ARM_SMMU_FEAT_SEV,
+			!smmu_cmdq_full(&smmu->cmdq));
+	if (ret)
+		return ret;
+
+	ret = arm_smmu_cmdq_build_cmd(cmd, ent);
+	if (ret)
+		return ret;
+
+	smmu_add_cmd_raw(smmu, cmd);
+	writel_relaxed(smmu->cmdq.llq.prod, smmu->cmdq.prod_reg);
+	return 0;
+}
+
+static int smmu_sync_cmd(struct hyp_arm_smmu_v3_device *smmu)
+{
+	int ret;
+	struct arm_smmu_cmdq_ent cmd = {
+		.opcode = CMDQ_OP_CMD_SYNC,
+	};
+
+	ret = smmu_add_cmd(smmu, &cmd);
+	if (ret)
+		return ret;
+
+	return smmu_wait(smmu->features & ARM_SMMU_FEAT_SEV,
+			 smmu_cmdq_empty(&smmu->cmdq));
+}
+
+__maybe_unused
+static int smmu_send_cmd(struct hyp_arm_smmu_v3_device *smmu,
+			 struct arm_smmu_cmdq_ent *cmd)
+{
+	int ret = smmu_add_cmd(smmu, cmd);
+
+	if (ret)
+		return ret;
+
+	return smmu_sync_cmd(smmu);
+}
+
 /* Put the device in a state that can be probed by the host driver. */
 static void smmu_deinit_device(struct hyp_arm_smmu_v3_device *smmu)
 {
-- 
2.52.0.rc1.455.g30608eb744-goog