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

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Date: Fri, 15 Dec 2023 08:37:26 +0800
From: "Yang, Weijiang" <weijiang.yang@...el.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>, Yi Liu <yi.l.liu@...el.com>
CC: <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 12/14/2023 9:33 PM, Baolu Lu wrote:
> 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.

Sure, I'll post fixup patches for the paths, thanks for confirmation!

>
> I assume Yi can fix this series in the next version.
>
> Best regards,
> baolu