6.14-stable review patch. If anyone has any objections, please let me know.
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From: Nicolin Chen nicolinc@nvidia.com
[ Upstream commit da0c56520e880441d0503d0cf0d6853dcfb5f1a4 ]
There is a DoS concern on the shared hardware event queue among devices passed through to VMs, that too many translation failures that belong to VMs could overflow the shared hardware event queue if those VMs or their VMMs don't handle/recover the devices properly.
The MEV bit in the STE allows to configure the SMMU HW to merge similar event records, though there is no guarantee. Set it in a nested STE for DoS mitigations.
In the future, we might want to enable the MEV for non-nested cases too such as domain->type == IOMMU_DOMAIN_UNMANAGED or even IOMMU_DOMAIN_DMA.
Link: https://patch.msgid.link/r/8ed12feef67fc65273d0f5925f401a81f56acebe.17417197... Reviewed-by: Jason Gunthorpe jgg@nvidia.com Reviewed-by: Pranjal Shrivastava praan@google.com Acked-by: Will Deacon will@kernel.org Signed-off-by: Nicolin Chen nicolinc@nvidia.com Signed-off-by: Jason Gunthorpe jgg@nvidia.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c | 2 ++ drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 4 ++-- drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 1 + 3 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c index 5aa2e7af58b47..34a0be59cd919 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3-iommufd.c @@ -43,6 +43,8 @@ static void arm_smmu_make_nested_cd_table_ste( target->data[0] |= nested_domain->ste[0] & ~cpu_to_le64(STRTAB_STE_0_CFG); target->data[1] |= nested_domain->ste[1]; + /* Merge events for DoS mitigations on eventq */ + target->data[1] |= cpu_to_le64(STRTAB_STE_1_MEV); }
/* 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 358072b4e293e..59749e8180afc 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c @@ -1052,7 +1052,7 @@ void arm_smmu_get_ste_used(const __le64 *ent, __le64 *used_bits) cpu_to_le64(STRTAB_STE_1_S1DSS | STRTAB_STE_1_S1CIR | STRTAB_STE_1_S1COR | STRTAB_STE_1_S1CSH | STRTAB_STE_1_S1STALLD | STRTAB_STE_1_STRW | - STRTAB_STE_1_EATS); + STRTAB_STE_1_EATS | STRTAB_STE_1_MEV); used_bits[2] |= cpu_to_le64(STRTAB_STE_2_S2VMID);
/* @@ -1068,7 +1068,7 @@ void arm_smmu_get_ste_used(const __le64 *ent, __le64 *used_bits) if (cfg & BIT(1)) { used_bits[1] |= cpu_to_le64(STRTAB_STE_1_S2FWB | STRTAB_STE_1_EATS | - STRTAB_STE_1_SHCFG); + STRTAB_STE_1_SHCFG | STRTAB_STE_1_MEV); used_bits[2] |= cpu_to_le64(STRTAB_STE_2_S2VMID | STRTAB_STE_2_VTCR | STRTAB_STE_2_S2AA64 | STRTAB_STE_2_S2ENDI | 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 bd9d7c85576a2..7290bd4c2bb0a 100644 --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h @@ -266,6 +266,7 @@ static inline u32 arm_smmu_strtab_l2_idx(u32 sid) #define STRTAB_STE_1_S1COR GENMASK_ULL(5, 4) #define STRTAB_STE_1_S1CSH GENMASK_ULL(7, 6)
+#define STRTAB_STE_1_MEV (1UL << 19) #define STRTAB_STE_1_S2FWB (1UL << 25) #define STRTAB_STE_1_S1STALLD (1UL << 27)