Re: [Linuxarm] Re: [PATCH v14 07/13] iommu/smmuv3: Implement cache_invalidate

Auger Eric
2021-03-22T09:06:22Z

Hi Chenxiang,

On 3/22/21 7:40 AM, chenxiang (M) wrote:
> Hi Eric,
>
>
> 在 2021/3/20 1:36, Auger Eric 写道:
>> Hi Chenxiang,
>>
>> On 3/4/21 8:55 AM, chenxiang (M) wrote:
>>> Hi Eric,
>>>
>>>
>>> 在 2021/2/24 4:56, Eric Auger 写道:
>>>> Implement domain-selective, pasid selective and page-selective
>>>> IOTLB invalidations.
>>>>
>>>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>>>
>>>> ---
>>>>
>>>> v13 -> v14:
>>>> - Add domain invalidation
>>>> - do global inval when asid is not provided with addr
>>>>    granularity
>>>>
>>>> v7 -> v8:
>>>> - ASID based invalidation using iommu_inv_pasid_info
>>>> - check ARCHID/PASID flags in addr based invalidation
>>>> - use __arm_smmu_tlb_inv_context and __arm_smmu_tlb_inv_range_nosync
>>>>
>>>> v6 -> v7
>>>> - check the uapi version
>>>>
>>>> v3 -> v4:
>>>> - adapt to changes in the uapi
>>>> - add support for leaf parameter
>>>> - do not use arm_smmu_tlb_inv_range_nosync or arm_smmu_tlb_inv_context
>>>>    anymore
>>>>
>>>> v2 -> v3:
>>>> - replace __arm_smmu_tlb_sync by arm_smmu_cmdq_issue_sync
>>>>
>>>> v1 -> v2:
>>>> - properly pass the asid
>>>> ---
>>>>   drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 74
>>>> +++++++++++++++++++++
>>>>   1 file changed, 74 insertions(+)
>>>>
>>>> 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 4c19a1114de4..df3adc49111c 100644
>>>> --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>>> +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c
>>>> @@ -2949,6 +2949,79 @@ static void
>>>> arm_smmu_detach_pasid_table(struct iommu_domain *domain)
>>>>       mutex_unlock(&smmu_domain->init_mutex);
>>>>   }
>>>>   +static int
>>>> +arm_smmu_cache_invalidate(struct iommu_domain *domain, struct
>>>> device *dev,
>>>> +              struct iommu_cache_invalidate_info *inv_info)
>>>> +{
>>>> +    struct arm_smmu_cmdq_ent cmd = {.opcode = CMDQ_OP_TLBI_NSNH_ALL};
>>>> +    struct arm_smmu_domain *smmu_domain = to_smmu_domain(domain);
>>>> +    struct arm_smmu_device *smmu = smmu_domain->smmu;
>>>> +
>>>> +    if (smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
>>>> +        return -EINVAL;
>>>> +
>>>> +    if (!smmu)
>>>> +        return -EINVAL;
>>>> +
>>>> +    if (inv_info->version != IOMMU_CACHE_INVALIDATE_INFO_VERSION_1)
>>>> +        return -EINVAL;
>>>> +
>>>> +    if (inv_info->cache & IOMMU_CACHE_INV_TYPE_PASID ||
>>>> +        inv_info->cache & IOMMU_CACHE_INV_TYPE_DEV_IOTLB) {
>>>> +        return -ENOENT;
>>>> +    }
>>>> +
>>>> +    if (!(inv_info->cache & IOMMU_CACHE_INV_TYPE_IOTLB))
>>>> +        return -EINVAL;
>>>> +
>>>> +    /* IOTLB invalidation */
>>>> +
>>>> +    switch (inv_info->granularity) {
>>>> +    case IOMMU_INV_GRANU_PASID:
>>>> +    {
>>>> +        struct iommu_inv_pasid_info *info =
>>>> +            &inv_info->granu.pasid_info;
>>>> +
>>>> +        if (info->flags & IOMMU_INV_ADDR_FLAGS_PASID)
>>>> +            return -ENOENT;
>>>> +        if (!(info->flags & IOMMU_INV_PASID_FLAGS_ARCHID))
>>>> +            return -EINVAL;
>>>> +
>>>> +        __arm_smmu_tlb_inv_context(smmu_domain, info->archid);
>>>> +        return 0;
>>>> +    }
>>>> +    case IOMMU_INV_GRANU_ADDR:
>>>> +    {
>>>> +        struct iommu_inv_addr_info *info = &inv_info->granu.addr_info;
>>>> +        size_t size = info->nb_granules * info->granule_size;
>>>> +        bool leaf = info->flags & IOMMU_INV_ADDR_FLAGS_LEAF;
>>>> +
>>>> +        if (info->flags & IOMMU_INV_ADDR_FLAGS_PASID)
>>>> +            return -ENOENT;
>>>> +
>>>> +        if (!(info->flags & IOMMU_INV_ADDR_FLAGS_ARCHID))
>>>> +            break;
>>>> +
>>>> +        arm_smmu_tlb_inv_range_domain(info->addr, size,
>>>> +                          info->granule_size, leaf,
>>>> +                          info->archid, smmu_domain);
>>> Is it possible to add a check before the function to make sure that
>>> info->granule_size can be recognized by SMMU?
>>> There is a scenario which will cause TLBI issue: RIL feature is enabled
>>> on guest but is disabled on host, and then on
>>> host it just invalidate 4K/2M/1G once a time, but from QEMU,
>>> info->nb_granules is always 1 and info->granule_size = size,
>>> if size is not equal to 4K or 2M or 1G (for example size = granule_size
>>> is 5M), it will only part of the size it wants to invalidate.
>
> Do you have any idea about this issue?

At the QEMU VFIO notifier level, when I fill the struct
iommu_cache_invalidate_info, I currently miss the granule info, hence
this weird choice of setting setting info->nb_granules is always 1 and
info->granule_size = size. I think in arm_smmu_cache_invalidate() I need
to convert this info back to a the leaf page size, in case the host does
not support RIL. Just as it is done in __arm_smmu_tlb_inv_range if RIL
is supported.

Does it makes sense to you?

Thank you for spotting the issue.

Eric
>
>>>
>>> I think maybe we can add a check here: if RIL is not enabled and also
>>> size is not the granule_size (4K/2M/1G) supported by
>>> SMMU hardware, can we just simply use the smallest granule_size
>>> supported by hardware all the time?
>>>
>>>> +
>>>> +        arm_smmu_cmdq_issue_sync(smmu);
>>>> +        return 0;
>>>> +    }
>>>> +    case IOMMU_INV_GRANU_DOMAIN:
>>>> +        break;
>>> I check the qemu code
>>> (https://github.com/eauger/qemu/tree/v5.2.0-2stage-rfcv8), for opcode
>>> CMD_TLBI_NH_ALL or CMD_TLBI_NSNH_ALL from guest OS
>>> it calls smmu_inv_notifiers_all() to unamp all notifiers of all mr's,
>>> but it seems not set event.entry.granularity which i think it should set
>>> IOMMU_INV_GRAN_ADDR.
>> this is because IOMMU_INV_GRAN_ADDR = 0. But for clarity I should rather
>> set it explicitly ;-)
>
> ok
>
>>> BTW, for opcode CMD_TLBI_NH_ALL or CMD_TLBI_NSNH_ALL, it needs to unmap
>>> size = 0x1000000000000 on 48bit system (it may spend much time),  maybe
>>> it is better
>>> to set it as IOMMU_INV_GRANU_DOMAIN, then in host OS, send TLBI_NH_ALL
>>> directly when IOMMU_INV_GRANU_DOMAIN.
>> Yes you're right. If the host does not support RIL then it is an issue.
>> This is going to be fixed in the next version.
>
> Great
>
>>
>> Thank you for the report!
>>
>> Best Regards
>>
>> Eric
>>>
>>>> +    default:
>>>> +        return -EINVAL;
>>>> +    }
>>>> +
>>>> +    /* Global S1 invalidation */
>>>> +    cmd.tlbi.vmid   = smmu_domain->s2_cfg.vmid;
>>>> +    arm_smmu_cmdq_issue_cmd(smmu, &cmd);
>>>> +    arm_smmu_cmdq_issue_sync(smmu);
>>>> +    return 0;
>>>> +}
>>>> +
>>>>   static bool arm_smmu_dev_has_feature(struct device *dev,
>>>>                        enum iommu_dev_features feat)
>>>>   {
>>>> @@ -3048,6 +3121,7 @@ static struct iommu_ops arm_smmu_ops = {
>>>>       .put_resv_regions    = generic_iommu_put_resv_regions,
>>>>       .attach_pasid_table    = arm_smmu_attach_pasid_table,
>>>>       .detach_pasid_table    = arm_smmu_detach_pasid_table,
>>>> +    .cache_invalidate    = arm_smmu_cache_invalidate,
>>>>       .dev_has_feat        = arm_smmu_dev_has_feature,
>>>>       .dev_feat_enabled    = arm_smmu_dev_feature_enabled,
>>>>       .dev_enable_feat    = arm_smmu_dev_enable_feature,
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