linux-kernel - Re: [PATCH 8/8] iommu/vt-d: Add set_dev

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Message-ID: <4e08dc77-82ce-40ce-8a0c-ac9016186c23@linux.intel.com>
Date:   Thu, 14 Dec 2023 21:33:46 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     "Yang, Weijiang" <weijiang.yang@...el.com>,
        Yi Liu <yi.l.liu@...el.com>
Cc:     baolu.lu@...ux.intel.com, robin.murphy@....com,
        kevin.tian@...el.com, jgg@...dia.com, alex.williamson@...hat.com,
        joro@...tes.org, cohuck@...hat.com, eric.auger@...hat.com,
        nicolinc@...dia.com, kvm@...r.kernel.org, mjrosato@...ux.ibm.com,
        chao.p.peng@...ux.intel.com, yi.y.sun@...ux.intel.com,
        peterx@...hat.com, jasowang@...hat.com,
        shameerali.kolothum.thodi@...wei.com, lulu@...hat.com,
        suravee.suthikulpanit@....com, iommu@...ts.linux.dev,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        zhenzhong.duan@...el.com, joao.m.martins@...cle.com,
        xin.zeng@...el.com, yan.y.zhao@...el.com
Subject: Re: [PATCH 8/8] iommu/vt-d: Add set_dev_pasid callback for nested
 domain

On 2023/12/14 10:55, Yang, Weijiang wrote:
> On 11/27/2023 2:34 PM, Yi Liu wrote:
>> From: Lu Baolu <baolu.lu@...ux.intel.com>
>>
>> This allows the upper layers to set a nested type domain to a PASID of a
>> device if the PASID feature is supported by the IOMMU hardware.
>>
>> The set_dev_pasid callback for non-nest domain has already be there, so
>> this only needs to add it for nested domains.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> Signed-off-by: Yi Liu <yi.l.liu@...el.com>
>> ---
>>   drivers/iommu/intel/nested.c | 47 ++++++++++++++++++++++++++++++++++++
>>   1 file changed, 47 insertions(+)
>>
>> diff --git a/drivers/iommu/intel/nested.c b/drivers/iommu/intel/nested.c
>> index 44ad48db7ea0..f6f687750104 100644
>> --- a/drivers/iommu/intel/nested.c
>> +++ b/drivers/iommu/intel/nested.c
>> @@ -68,6 +68,52 @@ static int intel_nested_attach_dev(struct 
>> iommu_domain *domain,
>>       return 0;
>>   }
>> +static int intel_nested_set_dev_pasid(struct iommu_domain *domain,
>> +                      struct device *dev, ioasid_t pasid)
>> +{
>> +    struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +    struct dmar_domain *dmar_domain = to_dmar_domain(domain);
>> +    struct intel_iommu *iommu = info->iommu;
>> +    struct dev_pasid_info *dev_pasid;
>> +    unsigned long flags;
>> +    int ret = 0;
>> +
>> +    if (!pasid_supported(iommu))
>> +        return -EOPNOTSUPP;
>> +
>> +    if (iommu->agaw < dmar_domain->s2_domain->agaw)
>> +        return -EINVAL;
>> +
>> +    ret = 
>> prepare_domain_attach_device(&dmar_domain->s2_domain->domain, dev);
>> +    if (ret)
>> +        return ret;
>> +
>> +    dev_pasid = kzalloc(sizeof(*dev_pasid), GFP_KERNEL);
>> +    if (!dev_pasid)
>> +        return -ENOMEM;
>> +
>> +    ret = domain_attach_iommu(dmar_domain, iommu);
>> +    if (ret)
>> +        goto err_free;
>> +
>> +    ret = intel_pasid_setup_nested(iommu, dev, pasid, dmar_domain);
>> +    if (ret)
>> +        goto err_detach_iommu;
>> +
>> +    dev_pasid->dev = dev;
>> +    dev_pasid->pasid = pasid;
>> +    spin_lock_irqsave(&dmar_domain->lock, flags);
>> +    list_add(&dev_pasid->link_domain, &dmar_domain->dev_pasids);
>> +    spin_unlock_irqrestore(&dmar_domain->lock, flags);
> 
> ---> list_add(&dev_pasid->link_domain, &dmar_domain->dev_pasids);
> 
> dev_pasid is linked at later time, this leads to 
> domain->has_iotlb_device is not correctly set, which finally results 
> into a missing of device iotlb flush in iommu_flush_dev_iotlb()when it's 
> called.
> Check this call path:
> domain_attach_iommu()->domain_update_iommu_cap()->domain_update_iotlb()->domain->has_iotlb_device = has_iotlb_device; The ugly fixup is to call domain_update_iommu_cap() or domain_update_iotlb() here again before return.
> The similar issue is in intel_iommu_set_dev_pasid() and 
> intel_nested_attach_dev().

Yes, domain->has_iotlb_device must be updated whenever a domain is
attached to (or removed from) a RID or PASID. I would be grateful if you
could post some patches to fix the set_device_pasid and
nested_attach_dev paths.

I assume Yi can fix this series in the next version.

Best regards,
baolu