RE: [PATCH v3 2/3] iommu/vt-d: Track device aux-attach with subdevice_domain_info

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

Hi Baolu,

> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Tuesday, December 29, 2020 4:38 PM
> 
> Hi Yi,
> 
> On 2020/12/29 11:25, Liu Yi L wrote:
> > In the existing code, loop all devices attached to a domain does not
> > include sub-devices attached via iommu_aux_attach_device().
> >
> > This was found by when I'm working on the belwo patch, There is no
>                                              ^^^^^
> below

nice catch. 😉

> > device in the domain->devices list, thus unable to get the cap and
> > ecap of iommu unit. But this domain actually has subdevice which is
> > attached via aux-manner. But it is tracked by domain. This patch is
> > going to fix it.
> >
> > https://lore.kernel.org/kvm/1599734733-6431-17-git-send-email-
> yi.l.liu@intel.com/
> >
> > And this fix goes beyond the patch above, such sub-device tracking is
> > necessary for other cases. For example, flushing device_iotlb for a
> > domain which has sub-devices attached by auxiliary manner.
> >
> > Co-developed-by: Xin Zeng <xin.zeng@intel.com>
> > Signed-off-by: Xin Zeng <xin.zeng@intel.com>
> > Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> 
> Others look good to me.
> 
> Fixes: 67b8e02b5e761 ("iommu/vt-d: Aux-domain specific domain
> attach/detach")
> Acked-by: Lu Baolu <baolu.lu@linux.intel.com>

thanks,

Regards,
Yi Liu

> Best regards,
> baolu
> 
> > ---
> >   drivers/iommu/intel/iommu.c | 95 +++++++++++++++++++++++++++--------
> --
> >   include/linux/intel-iommu.h | 16 +++++--
> >   2 files changed, 82 insertions(+), 29 deletions(-)
> >
> > diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> > index 788119c5b021..d7720a836268 100644
> > --- a/drivers/iommu/intel/iommu.c
> > +++ b/drivers/iommu/intel/iommu.c
> > @@ -1877,6 +1877,7 @@ static struct dmar_domain *alloc_domain(int
> flags)
> >   		domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;
> >   	domain->has_iotlb_device = false;
> >   	INIT_LIST_HEAD(&domain->devices);
> > +	INIT_LIST_HEAD(&domain->subdevices);
> >
> >   	return domain;
> >   }
> > @@ -2547,7 +2548,7 @@ static struct dmar_domain
> *dmar_insert_one_dev_info(struct intel_iommu *iommu,
> >   	info->iommu = iommu;
> >   	info->pasid_table = NULL;
> >   	info->auxd_enabled = 0;
> > -	INIT_LIST_HEAD(&info->auxiliary_domains);
> > +	INIT_LIST_HEAD(&info->subdevices);
> >
> >   	if (dev && dev_is_pci(dev)) {
> >   		struct pci_dev *pdev = to_pci_dev(info->dev);
> > @@ -4475,33 +4476,61 @@ is_aux_domain(struct device *dev, struct
> iommu_domain *domain)
> >   			domain->type == IOMMU_DOMAIN_UNMANAGED;
> >   }
> >
> > -static void auxiliary_link_device(struct dmar_domain *domain,
> > -				  struct device *dev)
> > +static inline struct subdev_domain_info *
> > +lookup_subdev_info(struct dmar_domain *domain, struct device *dev)
> > +{
> > +	struct subdev_domain_info *sinfo;
> > +
> > +	if (!list_empty(&domain->subdevices)) {
> > +		list_for_each_entry(sinfo, &domain->subdevices,
> link_domain) {
> > +			if (sinfo->pdev == dev)
> > +				return sinfo;
> > +		}
> > +	}
> > +
> > +	return NULL;
> > +}
> > +
> > +static int auxiliary_link_device(struct dmar_domain *domain,
> > +				 struct device *dev)
> >   {
> >   	struct device_domain_info *info = get_domain_info(dev);
> > +	struct subdev_domain_info *sinfo = lookup_subdev_info(domain,
> dev);
> >
> >   	assert_spin_locked(&device_domain_lock);
> >   	if (WARN_ON(!info))
> > -		return;
> > +		return -EINVAL;
> > +
> > +	if (!sinfo) {
> > +		sinfo = kzalloc(sizeof(*sinfo), GFP_ATOMIC);
> > +		sinfo->domain = domain;
> > +		sinfo->pdev = dev;
> > +		list_add(&sinfo->link_phys, &info->subdevices);
> > +		list_add(&sinfo->link_domain, &domain->subdevices);
> > +	}
> >
> > -	domain->auxd_refcnt++;
> > -	list_add(&domain->auxd, &info->auxiliary_domains);
> > +	return ++sinfo->users;
> >   }
> >
> > -static void auxiliary_unlink_device(struct dmar_domain *domain,
> > -				    struct device *dev)
> > +static int auxiliary_unlink_device(struct dmar_domain *domain,
> > +				   struct device *dev)
> >   {
> >   	struct device_domain_info *info = get_domain_info(dev);
> > +	struct subdev_domain_info *sinfo = lookup_subdev_info(domain,
> dev);
> > +	int ret;
> >
> >   	assert_spin_locked(&device_domain_lock);
> > -	if (WARN_ON(!info))
> > -		return;
> > +	if (WARN_ON(!info || !sinfo || sinfo->users <= 0))
> > +		return -EINVAL;
> >
> > -	list_del(&domain->auxd);
> > -	domain->auxd_refcnt--;
> > +	ret = --sinfo->users;
> > +	if (!ret) {
> > +		list_del(&sinfo->link_phys);
> > +		list_del(&sinfo->link_domain);
> > +		kfree(sinfo);
> > +	}
> >
> > -	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> > -		ioasid_put(domain->default_pasid);
> > +	return ret;
> >   }
> >
> >   static int aux_domain_add_dev(struct dmar_domain *domain,
> > @@ -4530,6 +4559,19 @@ static int aux_domain_add_dev(struct
> dmar_domain *domain,
> >   	}
> >
> >   	spin_lock_irqsave(&device_domain_lock, flags);
> > +	ret = auxiliary_link_device(domain, dev);
> > +	if (ret <= 0)
> > +		goto link_failed;
> > +
> > +	/*
> > +	 * Subdevices from the same physical device can be attached to the
> > +	 * same domain. For such cases, only the first subdevice attachment
> > +	 * needs to go through the full steps in this function. So if ret >
> > +	 * 1, just goto out.
> > +	 */
> > +	if (ret > 1)
> > +		goto out;
> > +
> >   	/*
> >   	 * iommu->lock must be held to attach domain to iommu and setup
> the
> >   	 * pasid entry for second level translation.
> > @@ -4548,10 +4590,9 @@ static int aux_domain_add_dev(struct
> dmar_domain *domain,
> >   						     domain->default_pasid);
> >   	if (ret)
> >   		goto table_failed;
> > -	spin_unlock(&iommu->lock);
> > -
> > -	auxiliary_link_device(domain, dev);
> >
> > +	spin_unlock(&iommu->lock);
> > +out:
> >   	spin_unlock_irqrestore(&device_domain_lock, flags);
> >
> >   	return 0;
> > @@ -4560,8 +4601,10 @@ static int aux_domain_add_dev(struct
> dmar_domain *domain,
> >   	domain_detach_iommu(domain, iommu);
> >   attach_failed:
> >   	spin_unlock(&iommu->lock);
> > +	auxiliary_unlink_device(domain, dev);
> > +link_failed:
> >   	spin_unlock_irqrestore(&device_domain_lock, flags);
> > -	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> > +	if (list_empty(&domain->subdevices) && domain->default_pasid > 0)
> >   		ioasid_put(domain->default_pasid);
> >
> >   	return ret;
> > @@ -4581,14 +4624,18 @@ static void aux_domain_remove_dev(struct
> dmar_domain *domain,
> >   	info = get_domain_info(dev);
> >   	iommu = info->iommu;
> >
> > -	auxiliary_unlink_device(domain, dev);
> > -
> > -	spin_lock(&iommu->lock);
> > -	intel_pasid_tear_down_entry(iommu, dev, domain->default_pasid,
> false);
> > -	domain_detach_iommu(domain, iommu);
> > -	spin_unlock(&iommu->lock);
> > +	if (!auxiliary_unlink_device(domain, dev)) {
> > +		spin_lock(&iommu->lock);
> > +		intel_pasid_tear_down_entry(iommu, dev,
> > +					    domain->default_pasid, false);
> > +		domain_detach_iommu(domain, iommu);
> > +		spin_unlock(&iommu->lock);
> > +	}
> >
> >   	spin_unlock_irqrestore(&device_domain_lock, flags);
> > +
> > +	if (list_empty(&domain->subdevices) && domain->default_pasid > 0)
> > +		ioasid_put(domain->default_pasid);
> >   }
> >
> >   static int prepare_domain_attach_device(struct iommu_domain
> *domain,
> > diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
> > index 94522685a0d9..09c6a0bf3892 100644
> > --- a/include/linux/intel-iommu.h
> > +++ b/include/linux/intel-iommu.h
> > @@ -533,11 +533,10 @@ struct dmar_domain {
> >   					/* Domain ids per IOMMU. Use u16
> since
> >   					 * domain ids are 16 bit wide
> according
> >   					 * to VT-d spec, section 9.3 */
> > -	unsigned int	auxd_refcnt;	/* Refcount of auxiliary attaching */
> >
> >   	bool has_iotlb_device;
> >   	struct list_head devices;	/* all devices' list */
> > -	struct list_head auxd;		/* link to device's auxiliary list */
> > +	struct list_head subdevices;	/* all subdevices' list */
> >   	struct iova_domain iovad;	/* iova's that belong to this domain
> */
> >
> >   	struct dma_pte	*pgd;		/* virtual address */
> > @@ -610,14 +609,21 @@ struct intel_iommu {
> >   	struct dmar_drhd_unit *drhd;
> >   };
> >
> > +/* Per subdevice private data */
> > +struct subdev_domain_info {
> > +	struct list_head link_phys;	/* link to phys device siblings */
> > +	struct list_head link_domain;	/* link to domain siblings */
> > +	struct device *pdev;		/* physical device derived from */
> > +	struct dmar_domain *domain;	/* aux-domain */
> > +	int users;			/* user count */
> > +};
> > +
> >   /* PCI domain-device relationship */
> >   struct device_domain_info {
> >   	struct list_head link;	/* link to domain siblings */
> >   	struct list_head global; /* link to global list */
> >   	struct list_head table;	/* link to pasid table */
> > -	struct list_head auxiliary_domains; /* auxiliary domains
> > -					     * attached to this device
> > -					     */
> > +	struct list_head subdevices; /* subdevices sibling */
> >   	u32 segment;		/* PCI segment number */
> >   	u8 bus;			/* PCI bus number */
> >   	u8 devfn;		/* PCI devfn number */
> >