linux-kernel - Re: [PATCH v7 14/23] iommu/smmuv3: Implement cache

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Date:   Mon, 13 May 2019 14:16:02 +0200
From:   Auger Eric <eric.auger@...hat.com>
To:     Robin Murphy <robin.murphy@....com>, eric.auger.pro@...il.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, kvmarm@...ts.cs.columbia.edu, joro@...tes.org,
        alex.williamson@...hat.com, jacob.jun.pan@...ux.intel.com,
        yi.l.liu@...el.com, jean-philippe.brucker@....com,
        will.deacon@....com
Cc:     kevin.tian@...el.com, ashok.raj@...el.com, marc.zyngier@....com,
        christoffer.dall@....com, peter.maydell@...aro.org,
        vincent.stehle@....com
Subject: Re: [PATCH v7 14/23] iommu/smmuv3: Implement cache_invalidate

Hi Robin,
On 5/8/19 5:01 PM, Robin Murphy wrote:
> On 08/04/2019 13:19, Eric Auger wrote:
>> Implement domain-selective and page-selective IOTLB invalidations.
>>
>> Signed-off-by: Eric Auger <eric.auger@...hat.com>
>>
>> ---
>> 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-smmu-v3.c | 60 +++++++++++++++++++++++++++++++++++++
>>   1 file changed, 60 insertions(+)
>>
>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>> index 1486baf53425..4366921d8318 100644
>> --- a/drivers/iommu/arm-smmu-v3.c
>> +++ b/drivers/iommu/arm-smmu-v3.c
>> @@ -2326,6 +2326,65 @@ 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_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_IOTLB) {
>> +        if (inv_info->granularity == IOMMU_INV_GRANU_PASID) {
>> +            struct arm_smmu_cmdq_ent cmd = {
>> +                .opcode = CMDQ_OP_TLBI_NH_ASID,
>> +                .tlbi = {
>> +                    .vmid = smmu_domain->s2_cfg.vmid,
>> +                    .asid = inv_info->pasid,
>> +                },
>> +            };
>> +
>> +            arm_smmu_cmdq_issue_cmd(smmu, &cmd);
>> +            arm_smmu_cmdq_issue_sync(smmu);
> 
> I'd much rather make arm_smmu_tlb_inv_context() understand nested
> domains than open-code commands all over the place.


> 
>> +
>> +        } else if (inv_info->granularity == IOMMU_INV_GRANU_ADDR) {
>> +            struct iommu_inv_addr_info *info = &inv_info->addr_info;
>> +            size_t size = info->nb_granules * info->granule_size;
>> +            bool leaf = info->flags & IOMMU_INV_ADDR_FLAGS_LEAF;
>> +            struct arm_smmu_cmdq_ent cmd = {
>> +                .opcode = CMDQ_OP_TLBI_NH_VA,
>> +                .tlbi = {
>> +                    .addr = info->addr,
>> +                    .vmid = smmu_domain->s2_cfg.vmid,
>> +                    .asid = info->pasid,
>> +                    .leaf = leaf,
>> +                },
>> +            };
>> +
>> +            do {
>> +                arm_smmu_cmdq_issue_cmd(smmu, &cmd);
>> +                cmd.tlbi.addr += info->granule_size;
>> +            } while (size -= info->granule_size);
>> +            arm_smmu_cmdq_issue_sync(smmu);
> 
> An this in particular I would really like to go all the way through
> io_pgtable_tlb_add_flush()/io_pgtable_sync() if at all possible. Hooking
> up range-based invalidations is going to be a massive headache if the
> abstraction isn't solid.

The concern is the host does not "own" the s1 config asid
(smmu_domain->s1_cfg.cd.asid is not set, practically). In our case the
asid only is passed by the userspace on CACHE_INVALIDATE ioctl call.

arm_smmu_tlb_inv_context and arm_smmu_tlb_inv_range_nosync use this field

Jean-Philippe highlighted that fact in
https://lkml.org/lkml/2019/1/11/1062 and suggested to open-code commands
instead, hence the current form.

Thanks

Eric
> 
> Robin.
> 
>> +        } else {
>> +            return -EINVAL;
>> +        }
>> +    }
>> +    if (inv_info->cache & IOMMU_CACHE_INV_TYPE_PASID ||
>> +        inv_info->cache & IOMMU_CACHE_INV_TYPE_DEV_IOTLB) {
>> +        return -ENOENT;
>> +    }
>> +    return 0;
>> +}
>> +
>>   static struct iommu_ops arm_smmu_ops = {
>>       .capable        = arm_smmu_capable,
>>       .domain_alloc        = arm_smmu_domain_alloc,
>> @@ -2346,6 +2405,7 @@ static struct iommu_ops arm_smmu_ops = {
>>       .put_resv_regions    = arm_smmu_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,
>>       .pgsize_bitmap        = -1UL, /* Restricted during device attach */
>>   };
>>