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

Kunkun Jiang
2021-04-09T09:43:30Z

On 2021/4/9 16:31, Auger Eric wrote:
> Hi Kunkun,
>
> On 4/9/21 6:48 AM, Kunkun Jiang wrote:
>> 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)
> this is not clear to me. See below.
>> 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.
> If the guest uses 4K granule, this means the pSMMU also supports 4K
> granule. Otherwise the corresponding CD is invalid (TG0/TG1 field desc).
> So in that case isn't it valid to send a RIL invalidation with tg = 12,
> right?
Dose "tg = 12" come from the smallest pSMMU supported page size?
Sorry, I overlooked the point you mentioned earlier.

My previous idea was to use granule_size to record the stage 1 page size
and nb_granules to record the number of pages.(Without deep consideration)
Now, it seems also okay to use the smallest pSMMU supported page size.

Thanks,
Kunkun Jiang
> Making sure the guest uses a valid pSMMU supported granule is the QEMU
> job I think, this should be done at the init phase before hitting CD
> invalid errors for sure.
>
> Thanks
>
> Eric
>
>> 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
>>> .
>>
> .