iommu/arm: Add BBM Level 2 smmu feature

For supporting BBM Level 2 for userspace mappings, we want to ensure
that the smmu also supports its own version of BBM Level 2. Luckily, the
smmu spec (IHI 0070G 3.21.1.3) is stricter than the aarch64 spec (DDI
0487K.a D8.16.2), so already guarantees that no aborts are raised when
BBM level 2 is claimed.

Add the feature and testing for it under arm_smmu_sva_supported().

Signed-off-by: Mikołaj Lenczewski <miko.lenczewski@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Link: https://lore.kernel.org/r/20250625113435.26849-4-miko.lenczewski@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
index 0601dece0a0d38302de8921106b60494ba1d1952..59a480974d80f035d6f5440b121a9951813bd65e 100644 (file)
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
@@ -220,6 +220,9 @@ bool arm_smmu_sva_supported(struct arm_smmu_device *smmu)
                feat_mask |= ARM_SMMU_FEAT_VAX;
        }
 
+       if (system_supports_bbml2_noabort())
+               feat_mask |= ARM_SMMU_FEAT_BBML2;
+
        if ((smmu->features & feat_mask) != feat_mask)
                return false;
 

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 10cc6dc26b7b7c36b937dd2cec929b57682d764f..39e933086f8fa07db856c2c7b586ccf1cbbb55c7 100644 (file)
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -4457,6 +4457,9 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
        if (FIELD_GET(IDR3_FWB, reg))
                smmu->features |= ARM_SMMU_FEAT_S2FWB;
 
+       if (FIELD_GET(IDR3_BBM, reg) == 2)
+               smmu->features |= ARM_SMMU_FEAT_BBML2;
+
        /* IDR5 */
        reg = readl_relaxed(smmu->base + ARM_SMMU_IDR5);
 

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 ea41d790463ed3cf6fc16aa2f1bd4f1e10a4eb9c..a33bf520ba97ea7612a9dac75b5085f398fe66e7 100644 (file)
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -60,6 +60,7 @@ struct arm_smmu_device;
 #define ARM_SMMU_IDR3                  0xc
 #define IDR3_FWB                       (1 << 8)
 #define IDR3_RIL                       (1 << 10)
+#define IDR3_BBM                       GENMASK(12, 11)
 
 #define ARM_SMMU_IDR5                  0x14
 #define IDR5_STALL_MAX                 GENMASK(31, 16)
@@ -755,6 +756,7 @@ struct arm_smmu_device {
 #define ARM_SMMU_FEAT_HA               (1 << 21)
 #define ARM_SMMU_FEAT_HD               (1 << 22)
 #define ARM_SMMU_FEAT_S2FWB            (1 << 23)
+#define ARM_SMMU_FEAT_BBML2            (1 << 24)
        u32                             features;
 
 #define ARM_SMMU_OPT_SKIP_PREFETCH     (1 << 0)