From: Robin Murphy <robin.murphy@arm.com>
Date: Tue, 17 Sep 2019 15:45:34 +0100
Subject: iommu/arm-smmu: Report USF more clearly
Git-commit: 931a0ba638e09a707e9a905cb6bea1fb1c6d4183
Patch-mainline: v5.5-rc1
References: bsc#1175713
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).
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Will Deacon <will@kernel.org>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
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 d2d357c87b61..bd6683c210da 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>
@@ -477,6 +478,8 @@ 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);
@@ -486,11 +489,19 @@ 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 ba0f05952dd9..409716410b0d 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