Subject: [PATCH v6 20/25] iommu/arm-smmu-v3-kvm: Share other queues

From: Mostafa Saleh <[email-masked]>
Date: Fri, 1 May 2026 11:19:22 +0000

Other queues as PRIQ and EVTQ doesn't need to be shadowed. However, we
need to make sure they are in a state that disallow them to be donated
to the hypervisor or guests. So, keep track of those and share them when
they get enabled.

Signed-off-by: Mostafa Saleh <[email-masked]>
---
 .../iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c  | 62 ++++++++++++++++++-
 .../iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h  |  4 ++
 2 files changed, 64 insertions(+), 2 deletions(-)

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 d92811ef2af5..e258690384f4 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
@@ -69,6 +69,16 @@ static bool is_smmu_enabled(struct hyp_arm_smmu_v3_device *smmu)
 	return FIELD_GET(CR0_SMMUEN, smmu->cr0);
 }
 
+static bool is_evtq_enabled(struct hyp_arm_smmu_v3_device *smmu)
+{
+	return FIELD_GET(CR0_EVTQEN, smmu->cr0);
+}
+
+static bool is_priq_enabled(struct hyp_arm_smmu_v3_device *smmu)
+{
+	return FIELD_GET(CR0_PRIQEN, smmu->cr0);
+}
+
 /*
  * CMDQ, STE host copies are accessed by the hypervisor, we share them to
  * - Prevent the host from passing protected VM memory.
@@ -647,6 +657,14 @@ static void smmu_emulate_cmdq_disable(struct hyp_arm_smmu_v3_device *smmu)
 				   cmdq_size(&smmu->cmdq_host)));
 }
 
+static void smmu_emulate_queue(unsigned long q_base, size_t ent_size_shift)
+{
+	phys_addr_t base = q_base & Q_BASE_ADDR_MASK;
+	size_t size = 1UL << (FIELD_GET(Q_BASE_LOG2SIZE, q_base) + ent_size_shift);
+
+	WARN_ON(smmu_share_pages(base ,size));
+}
+
 static bool smmu_dabt_device(struct hyp_arm_smmu_v3_device *smmu,
 			     struct user_pt_regs *regs,
 			     u64 esr, u32 off)
@@ -748,12 +766,31 @@ static bool smmu_dabt_device(struct hyp_arm_smmu_v3_device *smmu,
 		if (is_write) {
 			bool last_cmdq_en = is_cmdq_enabled(smmu);
 			bool last_smmu_en = is_smmu_enabled(smmu);
+			bool last_evtq_en = is_evtq_enabled(smmu);
+			bool last_priq_en = is_priq_enabled(smmu);
 
 			smmu->cr0 = val;
 			if (!last_cmdq_en && is_cmdq_enabled(smmu))
 				smmu_emulate_cmdq_enable(smmu);
 			else if (last_cmdq_en && !is_cmdq_enabled(smmu))
 				smmu_emulate_cmdq_disable(smmu);
+
+			/*
+			 * Share PRI and EVTQ to avoid the host using them to write to
+			 * protected memory. However, panic on disable for those queues
+			 * as that is more complicated, unsharing from here can lead to
+			 * use-after-unshare issues, and requires ordering with cr0ack.
+			 * As the host never disable those queues, don't support that.
+			 */
+			if (!last_evtq_en && is_evtq_enabled(smmu))
+				smmu_emulate_queue(smmu->evtq_base, EVTQ_ENT_SZ_SHIFT);
+			else if (last_evtq_en && !is_evtq_enabled(smmu))
+				WARN_ON(1);
+			if (!last_priq_en && is_priq_enabled(smmu))
+				smmu_emulate_queue(smmu->priq_base, PRIQ_ENT_SZ_SHIFT);
+			else if (last_priq_en && !is_priq_enabled(smmu))
+				WARN_ON(1);
+
 			if (!last_smmu_en && is_smmu_enabled(smmu))
 				smmu_emulate_enable(smmu);
 			else if (last_smmu_en && !is_smmu_enabled(smmu))
@@ -779,6 +816,29 @@ static bool smmu_dabt_device(struct hyp_arm_smmu_v3_device *smmu,
 		mask = read_write;
 		break;
 	}
+	case ARM_SMMU_EVTQ_BASE:
+		if (len != sizeof(u64))
+			break;
+
+		if (is_write) {
+			if (is_evtq_enabled(smmu))
+				break;
+			smmu->evtq_base = val;
+		}
+		mask = read_write;
+		break;
+
+	case ARM_SMMU_PRIQ_BASE:
+		if (len != sizeof(u64))
+			break;
+
+		if (is_write) {
+			if (is_priq_enabled(smmu))
+				break;
+			smmu->priq_base = val;
+		}
+		mask = read_write;
+		break;
 
 	/* Allowed 32 bit registers. */
 	case ARM_SMMU_EVTQ_PROD + SZ_64K:
@@ -801,9 +861,7 @@ static bool smmu_dabt_device(struct hyp_arm_smmu_v3_device *smmu,
 		mask = read_write;
 		break;
 	/* Allowed 64 bit registers. */
-	case ARM_SMMU_EVTQ_BASE:
 	case ARM_SMMU_EVTQ_IRQ_CFG0:
-	case ARM_SMMU_PRIQ_BASE:
 	case ARM_SMMU_PRIQ_IRQ_CFG0:
 	case ARM_SMMU_GERROR_IRQ_CFG0:
 		if (len != sizeof(u64))
diff --git a/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h b/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h
index 6a73cf6b8873..e811d51bdfaa 100644
--- a/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h
@@ -30,6 +30,8 @@
  * @host_ste_cfg	Host stream table config
  * @host_ste_base	Host stream table base
  * @strtab_cfg		Stream table as seen by HW
+ * @evtq_base		Host evtq base reg
+ * @priq_base		Host priq base reg
  */
 struct hyp_arm_smmu_v3_device {
 	phys_addr_t		mmio_addr;
@@ -52,6 +54,8 @@ struct hyp_arm_smmu_v3_device {
 	u64			host_ste_cfg;
 	u64			host_ste_base;
 	struct arm_smmu_strtab_cfg strtab_cfg;
+	unsigned long		evtq_base;
+	unsigned long		priq_base;
 };
 
 extern size_t kvm_nvhe_sym(kvm_hyp_arm_smmu_v3_count);
-- 
2.54.0.545.g6539524ca2-goog