Re: [PATCH v7 12/23] iommu/smmuv3: Get prepared for nested stage support
From: Robin Murphy
Date: Wed May 08 2019 - 10:25:08 EST
On 08/04/2019 13:19, Eric Auger wrote:
To allow nested stage support, we need to store both
stage 1 and stage 2 configurations (and remove the former
union).
A nested setup is characterized by both s1_cfg and s2_cfg
set.
We introduce a new ste.abort field that will be set upon
guest stage1 configuration passing. If s1_cfg is NULL and
ste.abort is set, traffic can't pass. If ste.abort is not set,
S1 is bypassed.
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@xxxxxxxxxx>
---
v4 -> v5:
- reset ste.abort on detach
v3 -> v4:
- s1_cfg.nested_abort and nested_bypass removed.
- s/ste.nested/ste.abort
- arm_smmu_write_strtab_ent modifications with introduction
of local abort, bypass and translate local variables
- comment updated
v1 -> v2:
- invalidate the STE before moving from a live STE config to another
- add the nested_abort and nested_bypass fields
---
drivers/iommu/arm-smmu-v3.c | 35 ++++++++++++++++++++---------------
1 file changed, 20 insertions(+), 15 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index 21d027695181..e22e944ffc05 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -211,6 +211,7 @@
#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
@@ -514,6 +515,7 @@ struct arm_smmu_strtab_ent {
* configured according to the domain type.
*/
bool assigned;
+ bool abort;
struct arm_smmu_s1_cfg *s1_cfg;
struct arm_smmu_s2_cfg *s2_cfg;
};
@@ -628,10 +630,8 @@ struct arm_smmu_domain {
bool non_strict;
enum arm_smmu_domain_stage stage;
- union {
- struct arm_smmu_s1_cfg s1_cfg;
- struct arm_smmu_s2_cfg s2_cfg;
- };
+ struct arm_smmu_s1_cfg s1_cfg;
+ struct arm_smmu_s2_cfg s2_cfg;
struct iommu_domain domain;
@@ -1108,12 +1108,13 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
__le64 *dst, struct arm_smmu_strtab_ent *ste)
{
/*
- * This is hideously complicated, but we only really care about
- * three cases at the moment:
+ * We care about the following transitions:
*
* 1. Invalid (all zero) -> bypass/fault (init)
- * 2. Bypass/fault -> translation/bypass (attach)
- * 3. Translation/bypass -> bypass/fault (detach)
+ * 2. Bypass/fault -> single stage translation/bypass (attach)
+ * 3. single stage Translation/bypass -> bypass/fault (detach)
+ * 4. S2 -> S1 + S2 (attach_pasid_table)
+ * 5. S1 + S2 -> S2 (detach_pasid_table)
*
* Given that we can't update the STE atomically and the SMMU
* doesn't read the thing in a defined order, that leaves us
@@ -1124,7 +1125,7 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
* 3. Update Config, sync
*/
u64 val = le64_to_cpu(dst[0]);
- bool ste_live = false;
+ bool abort, bypass, translate, ste_live = false;
struct arm_smmu_cmdq_ent prefetch_cmd = {
.opcode = CMDQ_OP_PREFETCH_CFG,
.prefetch = {
@@ -1138,11 +1139,11 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
break;
case STRTAB_STE_0_CFG_S1_TRANS:
case STRTAB_STE_0_CFG_S2_TRANS:
+ case STRTAB_STE_0_CFG_NESTED:
ste_live = true;
break;
case STRTAB_STE_0_CFG_ABORT:
- if (disable_bypass)
- break;
+ break;
default:
BUG(); /* STE corruption */
}
@@ -1152,8 +1153,13 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
val = STRTAB_STE_0_V;
/* Bypass/fault */
- if (!ste->assigned || !(ste->s1_cfg || ste->s2_cfg)) {
- if (!ste->assigned && disable_bypass)
+
+ abort = (!ste->assigned && disable_bypass) || ste->abort;
+ translate = ste->s1_cfg || ste->s2_cfg;
+ bypass = !abort && !translate;
+
+ if (abort || bypass) {
+ 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);
@@ -1172,7 +1178,6 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
}
if (ste->s1_cfg) {
- BUG_ON(ste_live);
Hmm, I'm a little uneasy about just removing these checks altogether, as
there are still cases where rewriting a live entry is bogus, that we'd
really like to keep catching. Is the problem that it's hard to tell when
you're 'rewriting' the S2 config of a nested entry with the same thing
on attaching/detaching its S1 context?
Robin.
dst[1] = cpu_to_le64(
FIELD_PREP(STRTAB_STE_1_S1CIR, STRTAB_STE_1_S1C_CACHE_WBRA) |
FIELD_PREP(STRTAB_STE_1_S1COR, STRTAB_STE_1_S1C_CACHE_WBRA) |
@@ -1191,7 +1196,6 @@ static void arm_smmu_write_strtab_ent(struct arm_smmu_device *smmu, u32 sid,
}
if (ste->s2_cfg) {
- BUG_ON(ste_live);
dst[2] = cpu_to_le64(
FIELD_PREP(STRTAB_STE_2_S2VMID, ste->s2_cfg->vmid) |
FIELD_PREP(STRTAB_STE_2_VTCR, ste->s2_cfg->vtcr) |
@@ -1773,6 +1777,7 @@ static void arm_smmu_detach_dev(struct device *dev)
}
master->ste.assigned = false;
+ master->ste.abort = false;
arm_smmu_install_ste_for_dev(fwspec);
}