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

[Auger Eric <eric.auger@redhat.com>]

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?

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
>>>
>> .
> 
>