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iommu/arm: Add BBM Level 2 smmu feature

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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>
This commit is contained in:
Mikołaj Lenczewski
2025-06-25 11:34:34 +00:00
committed by Catalin Marinas
parent 5aa4b62576
commit 212c439bdd
3 changed files with 8 additions and 0 deletions
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3
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-sva.c
View File

@@ -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;

3
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
View File

@@ -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);

2
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
View File

@@ -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)