Re: [PATCH v14 06/13] iommu/smmuv3: Allow stage 1 invalidation with unmanaged ASIDs

Kunkun Jiang
2021-04-09T04:48:43Z

Hi Eric,

On 2021/4/8 20:30, Auger Eric wrote:
> Hi Kunkun,
>
> On 4/1/21 2:37 PM, Kunkun Jiang wrote:
>> Hi Eric,
>>
>> On 2021/2/24 4:56, Eric Auger wrote:
>>> With nested stage support, soon we will need to invalidate
>>> S1 contexts and ranges tagged with an unmanaged asid, this
>>> latter being managed by the guest. So let's introduce 2 helpers
>>> that allow to invalidate with externally managed ASIDs
>>>
>>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>>
>>> ---
>>>
>>> v13 -> v14
>>> - Actually send the NH_ASID command (reported by Xingang Wang)
>>> ---
>>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 38 ++++++++++++++++-----
>>>   1 file changed, 29 insertions(+), 9 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 5579ec4fccc8..4c19a1114de4 100644
>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>> @@ -1843,9 +1843,9 @@ int arm_smmu_atc_inv_domain(struct
>>> arm_smmu_domain *smmu_domain, int ssid,
>>>   }
>>>     /* IO_PGTABLE API */
>>> -static void arm_smmu_tlb_inv_context(void *cookie)
>>> +static void __arm_smmu_tlb_inv_context(struct arm_smmu_domain
>>> *smmu_domain,
>>> +                       int ext_asid)
>>>   {
>>> -    struct arm_smmu_domain *smmu_domain = cookie;
>>>       struct arm_smmu_device *smmu = smmu_domain->smmu;
>>>       struct arm_smmu_cmdq_ent cmd;
>>>   @@ -1856,7 +1856,13 @@ static void arm_smmu_tlb_inv_context(void
>>> *cookie)
>>>        * insertion to guarantee those are observed before the TLBI. Do be
>>>        * careful, 007.
>>>        */
>>> -    if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
>>> +    if (ext_asid >= 0) { /* guest stage 1 invalidation */
>>> +        cmd.opcode    = CMDQ_OP_TLBI_NH_ASID;
>>> +        cmd.tlbi.asid    = ext_asid;
>>> +        cmd.tlbi.vmid    = smmu_domain->s2_cfg.vmid;
>>> +        arm_smmu_cmdq_issue_cmd(smmu, &cmd);
>>> +        arm_smmu_cmdq_issue_sync(smmu);
>>> +    } else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
>>>           arm_smmu_tlb_inv_asid(smmu, smmu_domain->s1_cfg.cd.asid);
>>>       } else {
>>>           cmd.opcode    = CMDQ_OP_TLBI_S12_VMALL;
>>> @@ -1867,6 +1873,13 @@ static void arm_smmu_tlb_inv_context(void *cookie)
>>>       arm_smmu_atc_inv_domain(smmu_domain, 0, 0, 0);
>>>   }
>>>   +static void arm_smmu_tlb_inv_context(void *cookie)
>>> +{
>>> +    struct arm_smmu_domain *smmu_domain = cookie;
>>> +
>>> +    __arm_smmu_tlb_inv_context(smmu_domain, -1);
>>> +}
>>> +
>>>   static void __arm_smmu_tlb_inv_range(struct arm_smmu_cmdq_ent *cmd,
>>>                        unsigned long iova, size_t size,
>>>                        size_t granule,
>>> @@ -1926,9 +1939,10 @@ static void __arm_smmu_tlb_inv_range(struct
>>> arm_smmu_cmdq_ent *cmd,
>>>       arm_smmu_cmdq_batch_submit(smmu, &cmds);
>>>   }
>>>
>> Here is the part of code in __arm_smmu_tlb_inv_range():
>>>         if (smmu->features & ARM_SMMU_FEAT_RANGE_INV) {
>>>                 /* Get the leaf page size */
>>>                 tg = __ffs(smmu_domain->domain.pgsize_bitmap);
>>>
>>>                 /* Convert page size of 12,14,16 (log2) to 1,2,3 */
>>>                 cmd->tlbi.tg = (tg - 10) / 2;
>>>
>>>                 /* Determine what level the granule is at */
>>>                 cmd->tlbi.ttl = 4 - ((ilog2(granule) - 3) / (tg - 3));
>>>
>>>                 num_pages = size >> tg;
>>>         }
>> When pSMMU supports RIL, we get the leaf page size by __ffs(smmu_domain->
>> domain.pgsize_bitmap). In nested mode, it is determined by host
>> PAGE_SIZE. If
>> the host kernel and guest kernel has different translation granule (e.g.
>> host 16K,
>> guest 4K), __arm_smmu_tlb_inv_range() will issue an incorrect tlbi command.
>>
>> Do you have any idea about this issue?
> I think this is the same issue as the one reported by Chenxiang
>
> https://lore.kernel.org/lkml/15938ed5-2095-e903-a290-333c299015a2@hisilicon.com/
>
> In case RIL is not supported by the host, next version will use the
> smallest pSMMU supported page size, as done in __arm_smmu_tlb_inv_range
>
> Thanks
>
> Eric
I think they are different. In normal cases, when we want to invalidate the
cache of stage 1, we should use the granule size supported by vSMMU to
implement and issue an tlbi command if pSMMU supports RIL.

But in the current __arm_smmu_tlb_inv_range(), it always uses the granule
size supported by host.
(tg = __ffs(smmu_domain->domain.pgsize_bitmap);)

Let me explain more clearly.
Preconditions of this issue:
1. pSMMU supports RIL
2. host and guest use different translation granule (e.g. host 16K,
guest 4K)

Guest wants to invalidate 4K, so info->granule_size = 4K.
In __arm_smmu_tlb_inv_range(),   if pSMMU supports RIL and host 16K,
tg = 14, tlbi.tg = 2, tlbi.ttl = 4, tlbi.scale = 0, tlbi.num = -1. It is
an incorrect
tlbi command.

So it would be better to pass the leaf page size supported by vSMMU to
host.  Perhaps this issue and the one reported by Chenxiang can be solved
together.

Thanks,
Kunkun Jiang
>> Best Regards,
>> Kunkun Jiang
>>> -static void arm_smmu_tlb_inv_range_domain(unsigned long iova, size_t
>>> size,
>>> -                      size_t granule, bool leaf,
>>> -                      struct arm_smmu_domain *smmu_domain)
>>> +static void
>>> +arm_smmu_tlb_inv_range_domain(unsigned long iova, size_t size,
>>> +                  size_t granule, bool leaf, int ext_asid,
>>> +                  struct arm_smmu_domain *smmu_domain)
>>>   {
>>>       struct arm_smmu_cmdq_ent cmd = {
>>>           .tlbi = {
>>> @@ -1936,7 +1950,12 @@ static void
>>> arm_smmu_tlb_inv_range_domain(unsigned long iova, size_t size,
>>>           },
>>>       };
>>>   -    if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
>>> +    if (ext_asid >= 0) {  /* guest stage 1 invalidation */
>>> +        cmd.opcode    = smmu_domain->smmu->features &
>>> ARM_SMMU_FEAT_E2H ?
>>> +                  CMDQ_OP_TLBI_EL2_VA : CMDQ_OP_TLBI_NH_VA;
>>> +        cmd.tlbi.asid    = ext_asid;
>>> +        cmd.tlbi.vmid    = smmu_domain->s2_cfg.vmid;
>>> +    } else if (smmu_domain->stage == ARM_SMMU_DOMAIN_S1) {
>>>           cmd.opcode    = smmu_domain->smmu->features &
>>> ARM_SMMU_FEAT_E2H ?
>>>                     CMDQ_OP_TLBI_EL2_VA : CMDQ_OP_TLBI_NH_VA;
>>>           cmd.tlbi.asid    = smmu_domain->s1_cfg.cd.asid;
>>> @@ -1944,6 +1963,7 @@ static void
>>> arm_smmu_tlb_inv_range_domain(unsigned long iova, size_t size,
>>>           cmd.opcode    = CMDQ_OP_TLBI_S2_IPA;
>>>           cmd.tlbi.vmid    = smmu_domain->s2_cfg.vmid;
>>>       }
>>> +
>>>       __arm_smmu_tlb_inv_range(&cmd, iova, size, granule, smmu_domain);
>>>         /*
>>> @@ -1982,7 +2002,7 @@ static void arm_smmu_tlb_inv_page_nosync(struct
>>> iommu_iotlb_gather *gather,
>>>   static void arm_smmu_tlb_inv_walk(unsigned long iova, size_t size,
>>>                     size_t granule, void *cookie)
>>>   {
>>> -    arm_smmu_tlb_inv_range_domain(iova, size, granule, false, cookie);
>>> +    arm_smmu_tlb_inv_range_domain(iova, size, granule, false, -1,
>>> cookie);
>>>   }
>>>     static const struct iommu_flush_ops arm_smmu_flush_ops = {
>>> @@ -2523,7 +2543,7 @@ static void arm_smmu_iotlb_sync(struct
>>> iommu_domain *domain,
>>>         arm_smmu_tlb_inv_range_domain(gather->start,
>>>                         gather->end - gather->start + 1,
>>> -                      gather->pgsize, true, smmu_domain);
>>> +                      gather->pgsize, true, -1, smmu_domain);
>>>   }
>>>     static phys_addr_t
>>
> .