Whilst trying to bring-up an SMMUv2 implementation with the table
walker plumbed into a coherent interconnect, I noticed that the memory
transactions targetting the CPU caches from the SMMU were marked as
outer-shareable instead of inner-shareable.
After a bunch of digging, it seems that we actually need to program
CBARn.BPSHCFG for s1-s2-bypass contexts to act as non-shareable in order
for the shareability configured in the corresponding TTBCR not to be
overridden with an outer-shareable attribute.
Signed-off-by: Will Deacon <will.dea...@arm.com>
---
drivers/iommu/arm-smmu.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c
index 509f01f054d9..0ae4dd39197f 100644
--- a/drivers/iommu/arm-smmu.c
+++ b/drivers/iommu/arm-smmu.c
@@ -190,6 +190,9 @@
#define ARM_SMMU_GR1_CBAR(n) (0x0 + ((n) << 2))
#define CBAR_VMID_SHIFT 0
#define CBAR_VMID_MASK 0xff
+#define CBAR_S1_BPSHCFG_SHIFT 8
+#define CBAR_S1_BPSHCFG_MASK 3
+#define CBAR_S1_BPSHCFG_NSH 3
#define CBAR_S1_MEMATTR_SHIFT 12
#define CBAR_S1_MEMATTR_MASK 0xf
#define CBAR_S1_MEMATTR_WB 0xf
@@ -671,11 +674,16 @@ static void arm_smmu_init_context_bank(struct
arm_smmu_domain *smmu_domain)
if (smmu->version == 1)
reg |= root_cfg->irptndx << CBAR_IRPTNDX_SHIFT;
- /* Use the weakest memory type, so it is overridden by the pte */
- if (stage1)
- reg |= (CBAR_S1_MEMATTR_WB << CBAR_S1_MEMATTR_SHIFT);
- else
+ /*
+ * Use the weakest shareability/memory types, so they are
+ * overridden by the ttbcr/pte.
+ */
+ if (stage1) {
+ reg |= (CBAR_S1_BPSHCFG_NSH << CBAR_S1_BPSHCFG_SHIFT) |
+ (CBAR_S1_MEMATTR_WB << CBAR_S1_MEMATTR_SHIFT);
+ } else {
reg |= ARM_SMMU_CB_VMID(root_cfg) << CBAR_VMID_SHIFT;
+ }
writel_relaxed(reg, gr1_base + ARM_SMMU_GR1_CBAR(root_cfg->cbndx));
if (smmu->version > 1) {
--
1.8.2.2
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