Re: [PATCH v4 5/7] iommu/vt-d: Make device pasid attachment explicit

Baolu Lu
2023-04-19T02:26:35Z

On 4/19/23 5:32 AM, Jacob Pan wrote:
> On Mon, 10 Apr 2023 10:46:02 +0800, Baolu Lu<baolu.lu@linux.intel.com>
> wrote:
>
>> On 4/8/23 2:05 AM, Jacob Pan wrote:
>>> @@ -2429,10 +2475,11 @@ static int __init si_domain_init(int hw)
>>> return 0;
>>> }
>>>
>>> -static int dmar_domain_attach_device(struct dmar_domain *domain,
>>> - struct device *dev)
>>> +static int dmar_domain_attach_device_pasid(struct dmar_domain *domain,
>>> + struct device *dev, ioasid_t
>>> pasid) {
>>> struct device_domain_info *info = dev_iommu_priv_get(dev);
>>> + struct device_pasid_info *dev_pasid;
>>> struct intel_iommu *iommu;
>>> unsigned long flags;
>>> u8 bus, devfn;
>>> @@ -2442,43 +2489,57 @@ static int dmar_domain_attach_device(struct
>>> dmar_domain *domain, if (!iommu)
>>> return -ENODEV;
>>>
>>> + dev_pasid = kzalloc(sizeof(*dev_pasid), GFP_KERNEL);
>>> + if (!dev_pasid)
>>> + return -ENOMEM;
>>> +
>>> ret = domain_attach_iommu(domain, iommu);
>>> if (ret)
>>> - return ret;
>>> + goto exit_free;
>>> +
>>> info->domain = domain;
>>> + dev_pasid->pasid = pasid;
>>> + dev_pasid->dev = dev;
>>> spin_lock_irqsave(&domain->lock, flags);
>>> - list_add(&info->link, &domain->devices);
>>> + if (!info->dev_attached)
>>> + list_add(&info->link, &domain->devices);
>>> +
>>> + list_add(&dev_pasid->link_domain, &domain->dev_pasids);
>>> spin_unlock_irqrestore(&domain->lock, flags);
>>>
>>> /* PASID table is mandatory for a PCI device in scalable
>>> mode. */ if (sm_supported(iommu) && !dev_is_real_dma_subdevice(dev)) {
>>> /* Setup the PASID entry for requests without PASID:
>>> */ if (hw_pass_through && domain_type_is_si(domain))
>>> - ret = intel_pasid_setup_pass_through(iommu,
>>> domain,
>>> - dev, PASID_RID2PASID);
>>> + ret = intel_pasid_setup_pass_through(iommu,
>>> domain, dev, pasid); else if (domain->use_first_level)
>>> - ret = domain_setup_first_level(iommu, domain,
>>> dev,
>>> - PASID_RID2PASID);
>>> + ret = domain_setup_first_level(iommu, domain,
>>> dev, pasid); else
>>> - ret = intel_pasid_setup_second_level(iommu,
>>> domain,
>>> - dev, PASID_RID2PASID);
>>> + ret = intel_pasid_setup_second_level(iommu,
>>> domain, dev, pasid); if (ret) {
>>> - dev_err(dev, "Setup RID2PASID failed\n");
>>> + dev_err(dev, "Setup PASID %d failed\n", pasid);
>>> device_block_translation(dev);
>>> - return ret;
>>> + goto exit_free;
>>> }
>>> }
>>> + /* device context already activated, we are done */
>>> + if (info->dev_attached)
>>> + goto exit;
>>>
>>> ret = domain_context_mapping(domain, dev);
>>> if (ret) {
>>> dev_err(dev, "Domain context map failed\n");
>>> device_block_translation(dev);
>>> - return ret;
>>> + goto exit_free;
>>> }
>>>
>>> iommu_enable_pci_caps(info);
>>> -
>>> + info->dev_attached = 1;
>>> +exit:
>>> return 0;
>>> +exit_free:
>>> + kfree(dev_pasid);
>>> + return ret;
>>> }
>>>
>>> static bool device_has_rmrr(struct device *dev)
>>> @@ -4029,8 +4090,7 @@ static void device_block_translation(struct
>>> device *dev) iommu_disable_pci_caps(info);
>>> if (!dev_is_real_dma_subdevice(dev)) {
>>> if (sm_supported(iommu))
>>> - intel_pasid_tear_down_entry(iommu, dev,
>>> - PASID_RID2PASID,
>>> false);
>>> +
>>> intel_iommu_detach_device_pasid(&info->domain->domain, dev,
>>> PASID_RID2PASID); else domain_context_clear(info);
>>> }
>>> @@ -4040,6 +4100,7 @@ static void device_block_translation(struct
>>> device *dev)
>>> spin_lock_irqsave(&info->domain->lock, flags);
>>> list_del(&info->link);
>>> + info->dev_attached = 0;
>>> spin_unlock_irqrestore(&info->domain->lock, flags);
>>>
>>> domain_detach_iommu(info->domain, iommu);
>>> @@ -4186,7 +4247,7 @@ static int intel_iommu_attach_device(struct
>>> iommu_domain *domain, if (ret)
>>> return ret;
>>>
>>> - return dmar_domain_attach_device(to_dmar_domain(domain), dev);
>>> + return dmar_domain_attach_device_pasid(to_dmar_domain(domain),
>>> dev, PASID_RID2PASID); }
>> For VT-d driver, attach_dev and attach_dev_pasid have different
>> meanings. Merging them into one helper may lead to confusion. What do
>> you think of the following code? The dmar_domain_attach_device_pasid()
>> helper could be reused for attach_dev_pasid path.
> Per our previous discussion
> https://lore.kernel.org/lkml/ZAY4zd4OlgSz+puZ@nvidia.com/
> We wanted to remove the ordering dependency between attaching device and
> device_pasid. i.e. making the two equal at IOMMU API level.

Yes. That still holds.

>
> So from that perspective, attach_dev_pasid will include attach_dev if the
> device has not been attached. i.e.

I don't follow here. attach_dev and attach_dev_pasid are independent of
each other. So in any case, attach_dev_pasid shouldn't include
attach_dev.

> attach_dev includes set up device context and RID_PASID
> attach_dev_pasid also include set up device context and another PASID.

I guess that you are worrying about the case where the context entry and
pasid table are not setup yet in attach_dev_pasid path? In theory yes,
but not exist in reality. The best case is that we setup context entry
in probe_device path, but at present, perhaps we can simply check and
return failure in this case.

Any way, I'd suggest not mix two ops in a single function.

>
> No ordering requirement.
>

Best regards,
baolu