Because the non-strict mode introduces a vulnerability window, so add a bootup option to make the manager can choose which mode to be used. The default mode is IOMMU_STRICT.
Signed-off-by: Zhen Lei <thunder.leiz...@huawei.com> --- Documentation/admin-guide/kernel-parameters.txt | 12 ++++++++++ drivers/iommu/arm-smmu-v3.c | 32 ++++++++++++++++++++++--- 2 files changed, 41 insertions(+), 3 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index efc7aa7..0cc80bc 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1720,6 +1720,18 @@ nobypass [PPC/POWERNV] Disable IOMMU bypass, using IOMMU for PCI devices. + iommu_strict_mode= [arm-smmu-v3] + 0 - strict mode + Make sure all related TLBs to be invalidated before the + memory released. + 1 - non-strict mode + Put off TLBs invalidation and release memory first. This mode + introduces a vlunerability window, an untrusted device can + access the reused memory because the TLBs may still valid. + Please take full consideration before choosing this mode. + Note that, VFIO is always use strict mode. + others - strict mode + iommu.passthrough= [ARM64] Configure DMA to bypass the IOMMU by default. Format: { "0" | "1" } diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c index 4a198a0..9b72fc4 100644 --- a/drivers/iommu/arm-smmu-v3.c +++ b/drivers/iommu/arm-smmu-v3.c @@ -631,6 +631,24 @@ struct arm_smmu_option_prop { { 0, NULL}, }; +static u32 iommu_strict_mode __read_mostly = IOMMU_STRICT; + +static int __init setup_iommu_strict_mode(char *str) +{ + u32 strict_mode = IOMMU_STRICT; + + get_option(&str, &strict_mode); + if (strict_mode == IOMMU_NON_STRICT) { + iommu_strict_mode = strict_mode; + pr_warn("WARNING: iommu non-strict mode is chose.\n" + "It's good for scatter-gather performance but lacks full isolation\n"); + add_taint(TAINT_WARN, LOCKDEP_STILL_OK); + } + + return 0; +} +early_param("iommu_strict_mode", setup_iommu_strict_mode); + static inline void __iomem *arm_smmu_page1_fixup(unsigned long offset, struct arm_smmu_device *smmu) { @@ -1441,7 +1459,7 @@ static bool arm_smmu_capable(enum iommu_cap cap) case IOMMU_CAP_NOEXEC: return true; case IOMMU_CAP_NON_STRICT: - return true; + return (iommu_strict_mode == IOMMU_NON_STRICT) ? true : false; default: return false; } @@ -1750,6 +1768,14 @@ static int arm_smmu_attach_dev(struct iommu_domain *domain, struct device *dev) return ret; } +static u32 arm_smmu_strict_mode(struct iommu_domain *domain) +{ + if (iommu_strict_mode == IOMMU_NON_STRICT) + return IOMMU_DOMAIN_STRICT_MODE(domain); + + return IOMMU_STRICT; +} + static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova, phys_addr_t paddr, size_t size, int prot) { @@ -1769,7 +1795,7 @@ static int arm_smmu_map(struct iommu_domain *domain, unsigned long iova, if (!ops) return 0; - return ops->unmap(ops, iova | IOMMU_DOMAIN_STRICT_MODE(domain), size); + return ops->unmap(ops, iova | arm_smmu_strict_mode(domain), size); } static void arm_smmu_flush_iotlb_all(struct iommu_domain *domain) @@ -1784,7 +1810,7 @@ static void arm_smmu_iotlb_sync(struct iommu_domain *domain) { struct arm_smmu_device *smmu = to_smmu_domain(domain)->smmu; - if (smmu && (IOMMU_DOMAIN_STRICT_MODE(domain) == IOMMU_STRICT)) + if (smmu && (arm_smmu_strict_mode(domain) == IOMMU_STRICT)) __arm_smmu_tlb_sync(smmu); } -- 1.8.3 _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu