Hi,
On Tue, Sep 17, 2019 at 7:45 AM Robin Murphy <robin.mur...@arm.com> wrote:
>
> 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 <diand...@chromium.org>
nit: Cc, not CC.
> Signed-off-by: Robin Murphy <robin.mur...@arm.com>
> ---
> 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",
optional nit: "%#hx" instead of "0x%hx"
Reviewed-by: Douglas Anderson <diand...@chromium.org>
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