Although CONFIG_ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT is a welcome tool for smoking out inadequate firmware, the failure mode is non-obvious and can be confusing for end users. Add some special-case reporting of Unidentified Stream Faults to help clarify this particular symptom. Since we're adding yet another print to the mix, also break out an explicit ratelimit state to make sure everything stays together (and reduce the static storage footprint a little).
CC: Douglas Anderson <[email protected]> Signed-off-by: Robin Murphy <[email protected]> --- drivers/iommu/arm-smmu.c | 21 ++++++++++++++++----- drivers/iommu/arm-smmu.h | 2 ++ 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index b7cf24402a94..b27020fd6c90 100644 --- a/drivers/iommu/arm-smmu.c +++ b/drivers/iommu/arm-smmu.c @@ -36,6 +36,7 @@ #include <linux/pci.h> #include <linux/platform_device.h> #include <linux/pm_runtime.h> +#include <linux/ratelimit.h> #include <linux/slab.h> #include <linux/amba/bus.h> @@ -485,6 +486,8 @@ static irqreturn_t arm_smmu_global_fault(int irq, void *dev) { u32 gfsr, gfsynr0, gfsynr1, gfsynr2; struct arm_smmu_device *smmu = dev; + static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, + DEFAULT_RATELIMIT_BURST); gfsr = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_sGFSR); gfsynr0 = arm_smmu_gr0_read(smmu, ARM_SMMU_GR0_sGFSYNR0); @@ -494,11 +497,19 @@ static irqreturn_t arm_smmu_global_fault(int irq, void *dev) if (!gfsr) return IRQ_NONE; - dev_err_ratelimited(smmu->dev, - "Unexpected global fault, this could be serious\n"); - dev_err_ratelimited(smmu->dev, - "\tGFSR 0x%08x, GFSYNR0 0x%08x, GFSYNR1 0x%08x, GFSYNR2 0x%08x\n", - gfsr, gfsynr0, gfsynr1, gfsynr2); + if (__ratelimit(&rs)) { + if (IS_ENABLED(CONFIG_ARM_SMMU_DISABLE_BYPASS_BY_DEFAULT) && + (gfsr & sGFSR_USF)) + dev_err(smmu->dev, + "Blocked unknown Stream ID 0x%hx; boot with \"arm-smmu.disable_bypass=0\" to allow, but this may have security implications\n", + (u16)gfsynr1); + else + dev_err(smmu->dev, + "Unexpected global fault, this could be serious\n"); + dev_err(smmu->dev, + "\tGFSR 0x%08x, GFSYNR0 0x%08x, GFSYNR1 0x%08x, GFSYNR2 0x%08x\n", + gfsr, gfsynr0, gfsynr1, gfsynr2); + } arm_smmu_gr0_write(smmu, ARM_SMMU_GR0_sGFSR, gfsr); return IRQ_HANDLED; diff --git a/drivers/iommu/arm-smmu.h b/drivers/iommu/arm-smmu.h index c9c13b5785f2..eede28ecda6d 100644 --- a/drivers/iommu/arm-smmu.h +++ b/drivers/iommu/arm-smmu.h @@ -79,6 +79,8 @@ #define ID7_MINOR GENMASK(3, 0) #define ARM_SMMU_GR0_sGFSR 0x48 +#define sGFSR_USF BIT(1) + #define ARM_SMMU_GR0_sGFSYNR0 0x50 #define ARM_SMMU_GR0_sGFSYNR1 0x54 #define ARM_SMMU_GR0_sGFSYNR2 0x58 -- 2.21.0.dirty _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
