iommu/arm-smmu: Log CBFRSYNRA register on context fault

Bits[15:0] in CBFRSYNRA register contain information about
StreamID of the incoming transaction that generated the
fault. Dump CBFRSYNRA register to get this info.
This is specially useful in a distributed SMMU architecture
where multiple masters are connected to the SMMU.
SID information helps to quickly identify the faulting
master device.
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

drivers/iommu/arm-smmu-regs.h

@@ -147,6 +147,8 @@ enum arm_smmu_s2cr_privcfg {
 #define CBAR_IRPTNDX_SHIFT		24
 #define CBAR_IRPTNDX_MASK		0xff
 
+#define ARM_SMMU_GR1_CBFRSYNRA(n)	(0x400 + ((n) << 2))
+
 #define ARM_SMMU_GR1_CBA2R(n)		(0x800 + ((n) << 2))
 #define CBA2R_RW64_32BIT		(0 << 0)
 #define CBA2R_RW64_64BIT		(1 << 0)

drivers/iommu/arm-smmu.c

@@ -570,12 +570,13 @@ static const struct iommu_gather_ops arm_smmu_s2_tlb_ops_v1 = {
 
 static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
 {
-	u32 fsr, fsynr;
+	u32 fsr, fsynr, cbfrsynra;
 	unsigned long iova;
 	struct iommu_domain *domain = dev;
 	struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
 	struct arm_smmu_cfg *cfg = &smmu_domain->cfg;
 	struct arm_smmu_device *smmu = smmu_domain->smmu;
+	void __iomem *gr1_base = ARM_SMMU_GR1(smmu);
 	void __iomem *cb_base;
 
 	cb_base = ARM_SMMU_CB(smmu, cfg->cbndx);
@@ -586,10 +587,11 @@ static irqreturn_t arm_smmu_context_fault(int irq, void *dev)
 
 	fsynr = readl_relaxed(cb_base + ARM_SMMU_CB_FSYNR0);
 	iova = readq_relaxed(cb_base + ARM_SMMU_CB_FAR);
+	cbfrsynra = readl_relaxed(gr1_base + ARM_SMMU_GR1_CBFRSYNRA(cfg->cbndx));
 
 	dev_err_ratelimited(smmu->dev,
-	"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cb=%d\n",
-			    fsr, iova, fsynr, cfg->cbndx);
+	"Unhandled context fault: fsr=0x%x, iova=0x%08lx, fsynr=0x%x, cbfrsynra=0x%x, cb=%d\n",
+			    fsr, iova, fsynr, cbfrsynra, cfg->cbndx);
 
 	writel(fsr, cb_base + ARM_SMMU_CB_FSR);
 	return IRQ_HANDLED;