linux-kernel - [PATCH v4 21/28] iommu/arm-smmu-v3-kvm: Add CMDQ functions

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Message-ID: <20250819215156.2494305-22-smostafa@google.com>
Date: Tue, 19 Aug 2025 21:51:49 +0000
From: Mostafa Saleh <smostafa@...gle.com>
To: linux-kernel@...r.kernel.org, kvmarm@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, iommu@...ts.linux.dev
Cc: maz@...nel.org, oliver.upton@...ux.dev, joey.gouly@....com, 
	suzuki.poulose@....com, yuzenghui@...wei.com, catalin.marinas@....com, 
	will@...nel.org, robin.murphy@....com, jean-philippe@...aro.org, 
	qperret@...gle.com, tabba@...gle.com, jgg@...pe.ca, mark.rutland@....com, 
	praan@...gle.com, Mostafa Saleh <smostafa@...gle.com>
Subject: [PATCH v4 21/28] iommu/arm-smmu-v3-kvm: Add CMDQ functions

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@...gle.com>
---
 .../iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c  | 98 +++++++++++++++++++
 1 file changed, 98 insertions(+)

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 d3ab4b814be4..554229e466f3 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
@@ -20,6 +20,33 @@ struct hyp_arm_smmu_v3_device *kvm_hyp_arm_smmu_v3_smmus;
 	     (smmu) != &kvm_hyp_arm_smmu_v3_smmus[kvm_hyp_arm_smmu_v3_count]; \
 	     (smmu)++)
 
+/*
+ * Wait until @cond is true.
+ * Return 0 on success, or -ETIMEDOUT
+ */
+#define smmu_wait(_cond)					\
+({								\
+	int __ret = 0;						\
+	u64 delay = pkvm_time_get() + ARM_SMMU_POLL_TIMEOUT_US;	\
+								\
+	while (!(_cond)) {					\
+		if (pkvm_time_get() >= delay) {			\
+			__ret = -ETIMEDOUT;			\
+			break;					\
+		}						\
+	}							\
+	__ret;							\
+})
+
+#define smmu_wait_event(_smmu, _cond)				\
+({								\
+	if ((_smmu)->features & ARM_SMMU_FEAT_SEV) {		\
+		while (!(_cond))				\
+			wfe();					\
+	}							\
+	smmu_wait(_cond);					\
+})
+
 /* Transfer ownership of memory */
 static int smmu_take_pages(u64 phys, size_t size)
 {
@@ -62,6 +89,77 @@ static int smmu_unshare_pages(phys_addr_t addr, size_t size)
 	return 0;
 }
 
+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);
+	writel_relaxed(llq->prod, q->prod_reg);
+}
+
+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_event(smmu, !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);
+	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_event(smmu, 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)
 {
-- 
2.51.0.rc1.167.g924127e9c0-goog