RE: [PATCH v2 3/3] iommu/vt-d: Fix ineffective devTLB invalidation for subdevices

["Liu, Yi L" <yi.l.liu@intel.com>]

Hi Baolu,

Well received, all comments accepted. thanks.

Regards,
Yi Liu

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Wednesday, December 23, 2020 6:10 PM
> 
> Hi Yi,
> 
> On 2020/12/23 14:27, Liu Yi L wrote:
> > iommu_flush_dev_iotlb() is called to invalidate caches on device. It only
> > loops the devices which are full-attached to the domain. For sub-devices,
> > this is ineffective. This results in invalid caching entries left on the
> > device. Fix it by adding loop for subdevices as well. Also, the domain->
> > has_iotlb_device needs to be updated when attaching to subdevices.
> >
> > Fixes: 67b8e02b5e761 ("iommu/vt-d: Aux-domain specific domain
> attach/detach")
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> > ---
> >   drivers/iommu/intel/iommu.c | 63 +++++++++++++++++++++++++++---------
> -
> >   1 file changed, 47 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index acfe0a5b955e..e97c5ac1d7fc 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -726,6 +726,8 @@ static int domain_update_device_node(struct
> dmar_domain *domain)
> >   	return nid;
> >   }
> >
> > +static void domain_update_iotlb(struct dmar_domain *domain);
> > +
> >   /* Some capabilities may be different across iommus */
> >   static void domain_update_iommu_cap(struct dmar_domain *domain)
> >   {
> > @@ -739,6 +741,8 @@ static void domain_update_iommu_cap(struct
> dmar_domain *domain)
> >   	 */
> >   	if (domain->nid == NUMA_NO_NODE)
> >   		domain->nid = domain_update_device_node(domain);
> > +
> > +	domain_update_iotlb(domain);
> >   }
> >
> >   struct context_entry *iommu_context_addr(struct intel_iommu *iommu,
> u8 bus,
> > @@ -1459,6 +1463,18 @@ iommu_support_dev_iotlb (struct dmar_domain
> *domain, struct intel_iommu *iommu,
> >   	return NULL;
> >   }
> >
> > +static bool dev_iotlb_enabled(struct device_domain_info *info)
> > +{
> > +	struct pci_dev *pdev;
> > +
> > +	if (!info->dev || !dev_is_pci(info->dev))
> > +		return false;
> > +
> > +	pdev = to_pci_dev(info->dev);
> > +
> > +	return !!pdev->ats_enabled;
> > +}
> 
> I know this is just separated from below function. But isn't "(info &&
> info->ats_enabled)" is enough?
> 
> > +
> >   static void domain_update_iotlb(struct dmar_domain *domain)
> >   {
> >   	struct device_domain_info *info;
> > @@ -1466,17 +1482,20 @@ static void domain_update_iotlb(struct
> dmar_domain *domain)
> >
> >   	assert_spin_locked(&device_domain_lock);
> >
> > -	list_for_each_entry(info, &domain->devices, link) {
> > -		struct pci_dev *pdev;
> > -
> > -		if (!info->dev || !dev_is_pci(info->dev))
> > -			continue;
> > -
> > -		pdev = to_pci_dev(info->dev);
> > -		if (pdev->ats_enabled) {
> > +	list_for_each_entry(info, &domain->devices, link)
> > +		if (dev_iotlb_enabled(info)) {
> >   			has_iotlb_device = true;
> >   			break;
> >   		}
> > +
> > +	if (!has_iotlb_device) {
> > +		struct subdev_domain_info *sinfo;
> > +
> > +		list_for_each_entry(sinfo, &domain->subdevices, link_domain)
> > +			if (dev_iotlb_enabled(get_domain_info(sinfo->pdev)))
> {
> 
> Please make the code easier for reading by:
> 
> 			info = get_domain_info(sinfo->pdev);
> 			if (dev_iotlb_enabled(info))
> 				....
> 
> Best regards,
> baolu
> 
> > +				has_iotlb_device = true;
> > +				break;
> > +			}
> >   	}
> >
> >   	domain->has_iotlb_device = has_iotlb_device;
> > @@ -1557,25 +1576,37 @@ static void iommu_disable_dev_iotlb(struct
> device_domain_info *info)
> >   #endif
> >   }
> >
> > +static void __iommu_flush_dev_iotlb(struct device_domain_info *info,
> > +				    u64 addr, unsigned int mask)
> > +{
> > +	u16 sid, qdep;
> > +
> > +	if (!info || !info->ats_enabled)
> > +		return;
> > +
> > +	sid = info->bus << 8 | info->devfn;
> > +	qdep = info->ats_qdep;
> > +	qi_flush_dev_iotlb(info->iommu, sid, info->pfsid,
> > +			   qdep, addr, mask);
> > +}
> > +
> >   static void iommu_flush_dev_iotlb(struct dmar_domain *domain,
> >   				  u64 addr, unsigned mask)
> >   {
> > -	u16 sid, qdep;
> >   	unsigned long flags;
> >   	struct device_domain_info *info;
> > +	struct subdev_domain_info *sinfo;
> >
> >   	if (!domain->has_iotlb_device)
> >   		return;
> >
> >   	spin_lock_irqsave(&device_domain_lock, flags);
> > -	list_for_each_entry(info, &domain->devices, link) {
> > -		if (!info->ats_enabled)
> > -			continue;
> > +	list_for_each_entry(info, &domain->devices, link)
> > +		__iommu_flush_dev_iotlb(info, addr, mask);
> >
> > -		sid = info->bus << 8 | info->devfn;
> > -		qdep = info->ats_qdep;
> > -		qi_flush_dev_iotlb(info->iommu, sid, info->pfsid,
> > -				qdep, addr, mask);
> > +	list_for_each_entry(sinfo, &domain->subdevices, link_domain) {
> > +		__iommu_flush_dev_iotlb(get_domain_info(sinfo->pdev),
> > +					addr, mask);
> >   	}
> >   	spin_unlock_irqrestore(&device_domain_lock, flags);
> >   }
> >
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