[PATCH v2 27/40] iommu/arm-smmu-v3: Add SVA feature checking

Jean-Philippe Brucker
2018-05-11T19:06:28Z

Aggregate all sanity-checks for sharing CPU page tables with the SMMU
under a single ARM_SMMU_FEAT_SVA bit. For PCIe SVA, users also need to
check FEAT_ATS and FEAT_PRI. For platform SVM, they will most likely have
to check FEAT_STALLS.

Signed-off-by: Jean-Philippe Brucker <jean-philippe.brucker-5wv7dgnIgG8@public.gmane.org>

---
v1->v2: Add 52-bit PA cap and debug message
---
drivers/iommu/arm-smmu-v3.c | 72 +++++++++++++++++++++++++++++++++++++
1 file changed, 72 insertions(+)

diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 073cba33ae6c..2716e4a4d3f7 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -525,6 +525,7 @@ struct arm_smmu_device {
#define ARM_SMMU_FEAT_VAX (1 << 14)
#define ARM_SMMU_FEAT_E2H (1 << 15)
#define ARM_SMMU_FEAT_BTM (1 << 16)
+#define ARM_SMMU_FEAT_SVA (1 << 17)
u32 features;

#define ARM_SMMU_OPT_SKIP_PREFETCH (1 << 0)
@@ -2565,6 +2566,74 @@ static int arm_smmu_device_reset(struct arm_smmu_device *smmu, bool bypass)
return 0;
}

+static bool arm_smmu_supports_sva(struct arm_smmu_device *smmu)
+{
+ unsigned long reg, fld;
+ unsigned long oas;
+ unsigned long asid_bits;
+
+ u32 feat_mask = ARM_SMMU_FEAT_BTM | ARM_SMMU_FEAT_COHERENCY;
+
+ if ((smmu->features & feat_mask) != feat_mask)
+ return false;
+
+ if (!(smmu->pgsize_bitmap & PAGE_SIZE))
+ return false;
+
+ /*
+ * Get the smallest PA size of all CPUs (sanitized by cpufeature). We're
+ * not even pretending to support AArch32 here.
+ */
+ reg = read_sanitised_ftr_reg(SYS_ID_AA64MMFR0_EL1);
+ fld = cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR0_PARANGE_SHIFT);
+ switch (fld) {
+ case 0x0:
+ oas = 32;
+ break;
+ case 0x1:
+ oas = 36;
+ break;
+ case 0x2:
+ oas = 40;
+ break;
+ case 0x3:
+ oas = 42;
+ break;
+ case 0x4:
+ oas = 44;
+ break;
+ case 0x5:
+ oas = 48;
+ break;
+ case 0x6:
+ oas = 52;
+ break;
+ default:
+ return false;
+ }
+
+ /* abort if MMU outputs addresses greater than what we support. */
+ if (smmu->oas < oas)
+ return false;
+
+ /* We can support bigger ASIDs than the CPU, but not smaller */
+ fld = cpuid_feature_extract_unsigned_field(reg, ID_AA64MMFR0_ASID_SHIFT);
+ asid_bits = fld ? 16 : 8;
+ if (smmu->asid_bits < asid_bits)
+ return false;
+
+ /*
+ * See max_pinned_asids in arch/arm64/mm/context.c. The following is
+ * generally the maximum number of bindable processes.
+ */
+ if (IS_ENABLED(CONFIG_UNMAP_KERNEL_AT_EL0))
+ asid_bits--;
+ dev_dbg(smmu->dev, "%d shared contexts\n", (1 << asid_bits) -
+ num_possible_cpus() - 2);
+
+ return true;
+}
+
static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)
{
u32 reg;
@@ -2766,6 +2835,9 @@ static int arm_smmu_device_hw_probe(struct arm_smmu_device *smmu)

smmu->ias = max(smmu->ias, smmu->oas);

+ if (arm_smmu_supports_sva(smmu))
+ smmu->features |= ARM_SMMU_FEAT_SVA;
+
dev_info(smmu->dev, "ias %lu-bit, oas %lu-bit (features 0x%08x)\n",
smmu->ias, smmu->oas, smmu->features);
return 0;
--
2.17.0