Subject: [PATCH v6 13/25] iommu/arm-smmu-v3-kvm: Probe SMMU HW

From: Mostafa Saleh <[email-masked]>
Date: Fri, 1 May 2026 11:19:15 +0000

Probe SMMU features from the IDR register space, most of
the logic is common with the kernel.

Signed-off-by: Mostafa Saleh <[email-masked]>
---
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c   |  6 --
 drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h   |  6 ++
 .../iommu/arm/arm-smmu-v3/pkvm/arm-smmu-v3.c  | 78 +++++++++++++++++++
 .../iommu/arm/arm-smmu-v3/pkvm/arm_smmu_v3.h  |  6 ++
 4 files changed, 90 insertions(+), 6 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 61e6ab364086..157acde0436d 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4738,12 +4738,6 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu)
 	return 0;
 }
 
-#define IIDR_IMPLEMENTER_ARM		0x43b
-#define IIDR_PRODUCTID_ARM_MMU_600	0x483
-#define IIDR_PRODUCTID_ARM_MMU_700	0x487
-#define IIDR_PRODUCTID_ARM_MMU_L1	0x48a
-#define IIDR_PRODUCTID_ARM_MMU_S3	0x498
-
 static void arm_smmu_device_iidr_probe(struct arm_smmu_device *smmu)
 {
 	u32 reg;
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 64618299d03a..f904f4d19609 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -84,6 +84,12 @@ struct arm_vsmmu;
 #define IIDR_REVISION			GENMASK(15, 12)
 #define IIDR_IMPLEMENTER		GENMASK(11, 0)
 
+#define IIDR_IMPLEMENTER_ARM		0x43b
+#define IIDR_PRODUCTID_ARM_MMU_600	0x483
+#define IIDR_PRODUCTID_ARM_MMU_700	0x487
+#define IIDR_PRODUCTID_ARM_MMU_L1	0x48a
+#define IIDR_PRODUCTID_ARM_MMU_S3	0x498
+
 #define ARM_SMMU_AIDR			0x1C
 
 #define ARM_SMMU_CR0			0x20
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 9afc314d0acc..d9945db9e102 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
@@ -10,6 +10,7 @@
 #include <nvhe/mem_protect.h>
 
 #include "arm_smmu_v3.h"
+#include "../arm-smmu-v3.h"
 
 size_t __ro_after_init kvm_hyp_arm_smmu_v3_count;
 struct hyp_arm_smmu_v3_device *kvm_hyp_arm_smmu_v3_smmus;
@@ -26,6 +27,77 @@ static void smmu_deinit_device(struct hyp_arm_smmu_v3_device *smmu)
 	smmu->base = NULL;
 }
 
+static bool smmu_nesting_supported(struct hyp_arm_smmu_v3_device *smmu)
+{
+	unsigned int implementer, productid, variant, revision;
+	u32 reg;
+
+	if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1) ||
+	    !(smmu->features & ARM_SMMU_FEAT_TRANS_S2))
+		return false;
+
+	reg = readl_relaxed(smmu->base + ARM_SMMU_IIDR);
+	implementer = FIELD_GET(IIDR_IMPLEMENTER, reg);
+	productid = FIELD_GET(IIDR_PRODUCTID, reg);
+	variant = FIELD_GET(IIDR_VARIANT, reg);
+	revision = FIELD_GET(IIDR_REVISION, reg);
+
+	if (implementer != IIDR_IMPLEMENTER_ARM)
+		return true;
+
+	if (productid == IIDR_PRODUCTID_ARM_MMU_600)
+		return variant >= 2;
+	else if (productid == IIDR_PRODUCTID_ARM_MMU_700)
+		return !(variant < 1 || revision < 1);
+
+	return true;
+}
+
+/*
+ * Mini-probe and validation for the hypervisor.
+ */
+static int smmu_probe(struct hyp_arm_smmu_v3_device *smmu)
+{
+	u32 reg;
+
+	/* Similar to the kernel, rely on firmware override. */
+	if (!(smmu->features & ARM_SMMU_FEAT_COHERENCY))
+		return -EINVAL;
+
+	/* IDR0 */
+	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR0);
+
+	smmu->features |= smmu_idr0_features(reg);
+	if (!smmu_nesting_supported(smmu))
+		return -ENXIO;
+
+	if (!(smmu->features & (ARM_SMMU_FEAT_TT_LE | ARM_SMMU_FEAT_TT_BE)))
+		return -ENXIO;
+
+	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR1);
+	if (reg & (IDR1_TABLES_PRESET | IDR1_QUEUES_PRESET | IDR1_REL))
+		return -EINVAL;
+
+	smmu->sid_bits = FIELD_GET(IDR1_SIDSIZE, reg);
+	/* Follows the kernel logic */
+	if (smmu->sid_bits <= STRTAB_SPLIT)
+		smmu->features &= ~ARM_SMMU_FEAT_2_LVL_STRTAB;
+
+	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR3);
+	smmu->features |= smmu_idr3_features(reg);
+
+	reg = readl_relaxed(smmu->base + ARM_SMMU_IDR5);
+	smmu->pgsize_bitmap = smmu_idr5_to_pgsize(reg);
+
+	smmu->oas = smmu_idr5_to_oas(reg);
+	if (smmu->oas == 52)
+		smmu->pgsize_bitmap |= 1ULL << 42;
+	else if (!smmu->oas)
+		smmu->oas = 48;
+
+	return 0;
+}
+
 static int smmu_init_device(struct hyp_arm_smmu_v3_device *smmu)
 {
 	unsigned long haddr;
@@ -39,8 +111,14 @@ static int smmu_init_device(struct hyp_arm_smmu_v3_device *smmu)
 		return ret;
 
 	smmu->base = (void __iomem *)haddr;
+	ret = smmu_probe(smmu);
+	if (ret)
+		goto out_ret;
 
 	return 0;
+out_ret:
+	smmu_deinit_device(smmu);
+	return ret;
 }
 
 /* Called while is the host is still trusted. */
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 744ee2b7f0b4..82b84673e85b 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
@@ -12,12 +12,18 @@
  *
  * Other members are filled and used at runtime by the SMMU driver.
  * @base		Virtual address of SMMU registers
+ * @oas			PA size
+ * @pgsize_bitmap	Supported page sizes
+ * @sid_bits		Max number of SID bits supported
  */
 struct hyp_arm_smmu_v3_device {
 	phys_addr_t		mmio_addr;
 	size_t			mmio_size;
 	void __iomem		*base;
 	u32			features;
+	unsigned long		oas;
+	unsigned long		pgsize_bitmap;
+	unsigned int		sid_bits;
 };
 
 extern size_t kvm_nvhe_sym(kvm_hyp_arm_smmu_v3_count);
-- 
2.54.0.545.g6539524ca2-goog