On 2020/12/3 21:01, Auger Eric wrote:
Hi Kunkun,

On 12/3/20 1:32 PM, Kunkun Jiang wrote:
Hi Eric,

On 2020/11/18 19:21, Eric Auger wrote:
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.

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.au...@redhat.com>

---
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 | 64 +++++++++++++++++----
  drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.h |  2 +
  2 files changed, 56 insertions(+), 10 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 18ac5af1b284..412ea1bafa50 100644
--- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
+++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
@@ -1181,8 +1181,10 @@ static void arm_smmu_write_strtab_ent(struct 
arm_smmu_master *master, u32 sid,
         * three cases at the moment:
Now, it should be *five cases*.
         *
         * 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 or nested stage Translation/bypass -> bypass/fault (detach)
+        * 4. S2 -> S1 + S2 (attach_pasid_table)
I was testing this series on one of our hardware board with SMMUv3. And
I found while trying to /"//attach_pasid_table//"/,

the sequence of STE (host) config(bit[3:1]) is /"S2->abort->S1 + S2"/.
Because the maintenance is  /"Write everything apart///

/from dword 0, sync, write dword 0, sync"/ when we update the STE
(guest). Dose the sequence meet your expectation?
yes it does. I will fix the comments accordingly.

Is there anything to correct in the code or was it functional?

Thanks

Eric
No, thanks. I just want to clarify the sequence.   :)
+        * 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
@@ -1193,7 +1195,8 @@ 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, nested = false, translate = false;
        struct arm_smmu_device *smmu = NULL;
        struct arm_smmu_s1_cfg *s1_cfg;
        struct arm_smmu_s2_cfg *s2_cfg;
@@ -1233,6 +1236,8 @@ static void arm_smmu_write_strtab_ent(struct 
arm_smmu_master *master, u32 sid,
                default:
                        break;
                }
+               nested = s1_cfg->set && s2_cfg->set;
+               translate = s1_cfg->set || s2_cfg->set;
        }
if (val & STRTAB_STE_0_V) {
@@ -1240,23 +1245,36 @@ 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);
@@ -1274,8 +1292,16 @@ static void arm_smmu_write_strtab_ent(struct 
arm_smmu_master *master, u32 sid,
                return;
        }
+ BUG_ON(ste_live && !nested);
+
+       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) {
-               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) |
@@ -1294,7 +1320,14 @@ 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) |
@@ -1304,9 +1337,12 @@ 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)
@@ -1982,6 +2018,14 @@ 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 07f59252dd21..269779dee8d1 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
@@ -682,6 +683,7 @@ 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;
Thanks,

Kunkun Jiang

.

Thanks

Kunkun Jiang

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