[PATCH v14 04/13] iommu/smmuv3: Get prepared for nested stage support

Eric Auger
2021-02-23T20:57:36Z

When nested stage translation is setup, both s1_cfg and
s2_cfg are set.

We introduce a new smmu_domain abort field that will be set
upon guest stage1 configuration passing. If no guest stage1
config has been attached, it is ignored when writing the STE.

arm_smmu_write_strtab_ent() is modified to write both stage
fields in the STE and deal with the abort field.

In nested mode, only stage 2 is "finalized" as the host does
not own/configure the stage 1 context descriptor; guest does.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---
v13 -> v14:
- removed BUG_ON(ste_live && !nested) as this should never happen
- restored the old comment as there is always an abort in between
S2 -> S1 + S2 and S1 + S2 -> S2
- remove sparse warning

v10 -> v11:
- Fix an issue reported by Shameer when switching from with vSMMU
to without vSMMU. Despite the spec does not seem to mention it
seems to be needed to reset the 2 high 64b when switching from
S1+S2 cfg to S1 only. Especially dst[3] needs to be reset (S2TTB).
On some implementations, if the S2TTB is not reset, this causes
a C_BAD_STE error
---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 55 ++++++++++++++++++---
drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h | 2 +
2 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
index 14e5666c25dc..085a784dfaee 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1237,7 +1237,8 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
* 3. Update Config, sync
*/
u64 val = le64_to_cpu(dst[0]);
- bool ste_live = false;
+ bool s1_live = false, s2_live = false, ste_live;
+ bool abort, translate = false;
struct arm_smmu_device *smmu = NULL;
struct arm_smmu_s1_cfg *s1_cfg;
struct arm_smmu_s2_cfg *s2_cfg;
@@ -1277,6 +1278,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
default:
break;
}
+ translate = s1_cfg->set || s2_cfg->set;
}

if (val & STRTAB_STE_0_V) {
@@ -1284,23 +1286,36 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
case STRTAB_STE_0_CFG_BYPASS:
break;
case STRTAB_STE_0_CFG_S1_TRANS:
+ s1_live = true;
+ break;
case STRTAB_STE_0_CFG_S2_TRANS:
- ste_live = true;
+ s2_live = true;
+ break;
+ case STRTAB_STE_0_CFG_NESTED:
+ s1_live = true;
+ s2_live = true;
break;
case STRTAB_STE_0_CFG_ABORT:
- BUG_ON(!disable_bypass);
break;
default:
BUG(); /* STE corruption */
}
}

+ ste_live = s1_live || s2_live;
+
/* Nuke the existing STE_0 value, as we're going to rewrite it */
val = STRTAB_STE_0_V;

/* Bypass/fault */
- if (!smmu_domain || !(s1_cfg->set || s2_cfg->set)) {
- if (!smmu_domain && disable_bypass)
+
+ if (!smmu_domain)
+ abort = disable_bypass;
+ else
+ abort = smmu_domain->abort;
+
+ if (abort || !translate) {
+ if (abort)
val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_ABORT);
else
val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_BYPASS);
@@ -1318,11 +1333,17 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
return;
}

+ if (ste_live) {
+ /* First invalidate the live STE */
+ dst[0] = cpu_to_le64(STRTAB_STE_0_CFG_ABORT);
+ arm_smmu_sync_ste_for_sid(smmu, sid);
+ }
+
if (s1_cfg->set) {
u64 strw = smmu->features & ARM_SMMU_FEAT_E2H ?
STRTAB_STE_1_STRW_EL2 : STRTAB_STE_1_STRW_NSEL1;

- BUG_ON(ste_live);
+ BUG_ON(s1_live);
dst[1] = cpu_to_le64(
FIELD_PREP(STRTAB_STE_1_S1DSS, STRTAB_STE_1_S1DSS_SSID0) |
FIELD_PREP(STRTAB_STE_1_S1CIR, STRTAB_STE_1_S1C_CACHE_WBRA) |
@@ -1341,7 +1362,14 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
}

if (s2_cfg->set) {
- BUG_ON(ste_live);
+ u64 vttbr = s2_cfg->vttbr & STRTAB_STE_3_S2TTB_MASK;
+
+ if (s2_live) {
+ u64 s2ttb = le64_to_cpu(dst[3]) & STRTAB_STE_3_S2TTB_MASK;
+
+ BUG_ON(s2ttb != vttbr);
+ }
+
dst[2] = cpu_to_le64(
FIELD_PREP(STRTAB_STE_2_S2VMID, s2_cfg->vmid) |
FIELD_PREP(STRTAB_STE_2_VTCR, s2_cfg->vtcr) |
@@ -1351,9 +1379,12 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_master *master, u32 sid,
STRTAB_STE_2_S2PTW | STRTAB_STE_2_S2AA64 |
STRTAB_STE_2_S2R);

- dst[3] = cpu_to_le64(s2_cfg->vttbr & STRTAB_STE_3_S2TTB_MASK);
+ dst[3] = cpu_to_le64(vttbr);

val |= FIELD_PREP(STRTAB_STE_0_CFG, STRTAB_STE_0_CFG_S2_TRANS);
+ } else {
+ dst[2] = 0;
+ dst[3] = 0;
}

if (master->ats_enabled)
@@ -2154,6 +2185,14 @@ static int arm_smmu_domain_finalise(struct iommu_domain *domain,
return 0;
}

+ if (smmu_domain->stage == ARM_SMMU_DOMAIN_NESTED &&
+ (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1) ||
+ !(smmu->features & ARM_SMMU_FEAT_TRANS_S2))) {
+ dev_info(smmu_domain->smmu->dev,
+ "does not implement two stages\n");
+ return -EINVAL;
+ }
+
/* Restrict the stage to what we can actually support */
if (!(smmu->features & ARM_SMMU_FEAT_TRANS_S1))
smmu_domain->stage = ARM_SMMU_DOMAIN_S2;
diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
index ec2b77596b6a..eb0cc08e8240 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h
@@ -206,6 +206,7 @@
#define STRTAB_STE_0_CFG_BYPASS 4
#define STRTAB_STE_0_CFG_S1_TRANS 5
#define STRTAB_STE_0_CFG_S2_TRANS 6
+#define STRTAB_STE_0_CFG_NESTED 7

#define STRTAB_STE_0_S1FMT GENMASK_ULL(5, 4)
#define STRTAB_STE_0_S1FMT_LINEAR 0
@@ -722,6 +723,7 @@ struct arm_smmu_domain {
enum arm_smmu_domain_stage stage;
struct arm_smmu_s1_cfg s1_cfg;
struct arm_smmu_s2_cfg s2_cfg;
+ bool abort;

struct iommu_domain domain;

--
2.26.2