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Date:   Tue, 29 Dec 2020 16:38:20 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Liu Yi L <yi.l.liu@...el.com>, joro@...tes.org, will@...nel.org
Cc:     baolu.lu@...ux.intel.com, kevin.tian@...el.com,
        jacob.jun.pan@...ux.intel.com, ashok.raj@...el.com,
        jun.j.tian@...el.com, yi.y.sun@...el.com,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org,
        Xin Zeng <xin.zeng@...el.com>
Subject: Re: [PATCH v3 2/3] iommu/vt-d: Track device aux-attach with
 subdevice_domain_info

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

> 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@...el.com>
> Signed-off-by: Xin Zeng <xin.zeng@...el.com>
> Signed-off-by: Liu Yi L <yi.l.liu@...el.com>

Others look good to me.

Fixes: 67b8e02b5e761 ("iommu/vt-d: Aux-domain specific domain 
attach/detach")
Acked-by: Lu Baolu <baolu.lu@...ux.intel.com>

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 */
> 

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