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

[Jacob Pan <jacob.jun.pan@intel.com>]

Hi Yi,

On Sun, 20 Dec 2020 08:03:51 +0800, Liu Yi L <yi.l.liu@intel.com> wrote:

> In existing code, if wanting to loop all devices attached to a domain,
> current code can only loop the devices which are attached to the domain
> via normal manner. While for devices attached via auxiliary manner, this
> is subdevice, they are not tracked in the domain. This patch adds struct
How about "In the existing code, loop all devices attached to a domain does
not include sub-devices attached via iommu_aux_attach_device()."

> subdevice_domain_info which is created per domain attachment via auxiliary
> manner. So that such devices are also tracked in domain.
> 
> This was found by when I'm working on the belwo patch, There is no device
> in domain->devices, thus unable to get the cap and ecap of iommu unit. But
> this domain actually has one sub-device which is attached via aux-manner.
> This patch fixes the issue.
> 
> https://lore.kernel.org/kvm/1599734733-6431-17-git-send-email-yi.l.liu@intel.com/
> 
> But looks like, it doesn't affect me only. Such auxiliary track should be
> there for example if wanting to flush device_iotlb for a domain which has
> devices attached by auxiliray manner, then this fix is also necessary.
Perhaps:
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.

> This issue will also be fixed by another patch in this series with some
> additional changes based on the sudevice tracking framework introduced in
> this patch.
> 
> Co-developed-by: Xin Zeng <xin.zeng@intel.com>
> Signed-off-by: Xin Zeng <xin.zeng@intel.com>
> Co-developed-by: Liu Yi L <yi.l.liu@intel.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> Co-developed-by: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
>  drivers/iommu/intel/iommu.c | 92 ++++++++++++++++++++++++++++++++-----
>  include/linux/intel-iommu.h | 11 ++++-
>  2 files changed, 90 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index a49afa11673c..4274b4acc325 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -1881,6 +1881,7 @@ 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->sub_devices);
>  
>  	return domain;
>  }
> @@ -5172,33 +5173,79 @@ is_aux_domain(struct device *dev, struct
> iommu_domain *domain) domain->type == IOMMU_DOMAIN_UNMANAGED;
>  }
>  
> +static inline
> +void _auxiliary_link_device(struct dmar_domain *domain,
> +			    struct subdevice_domain_info *subinfo,
> +			    struct device *dev)
> +{
> +	subinfo->users++;
> +}
> +
why pass in more arguments than subinfo? the function name does not match
what it does, seems just refcount inc.

> +static inline
> +int _auxiliary_unlink_device(struct dmar_domain *domain,
> +			     struct subdevice_domain_info *subinfo,
> +			     struct device *dev)
> +{
> +	subinfo->users--;
> +	return subinfo->users;
ditto. why not just
 	return subinfo->users--;

> +}
> +
>  static void auxiliary_link_device(struct dmar_domain *domain,
>  				  struct device *dev)
>  {
>  	struct device_domain_info *info = get_domain_info(dev);
> +	struct subdevice_domain_info *subinfo;
>  
>  	assert_spin_locked(&device_domain_lock);
>  	if (WARN_ON(!info))
>  		return;
>  
> +	subinfo = kzalloc(sizeof(*subinfo), GFP_ATOMIC);
> +	if (!subinfo)
> +		return;
> +
> +	subinfo->domain = domain;
> +	subinfo->dev = dev;
> +	list_add(&subinfo->link_domain, &info->auxiliary_domains);
> +	list_add(&subinfo->link_phys, &domain->sub_devices);
> +	_auxiliary_link_device(domain, subinfo, dev);
or just opencode subinfo->users++?
>  	domain->auxd_refcnt++;
> -	list_add(&domain->auxd, &info->auxiliary_domains);
>  }
>  
> -static void auxiliary_unlink_device(struct dmar_domain *domain,
> -				    struct device *dev)
> +static struct subdevice_domain_info *
> +subdevice_domain_info_lookup(struct dmar_domain *domain, struct device
> *dev) +{
> +	struct subdevice_domain_info *subinfo;
> +
> +	assert_spin_locked(&device_domain_lock);
> +
> +	list_for_each_entry(subinfo, &domain->sub_devices, link_phys)
> +		if (subinfo->dev == dev)
> +			return subinfo;
> +
> +	return NULL;
> +}
> +
> +static int auxiliary_unlink_device(struct dmar_domain *domain,
> +				   struct subdevice_domain_info *subinfo,
> +				   struct device *dev)
>  {
>  	struct device_domain_info *info = get_domain_info(dev);
> +	int ret;
>  
>  	assert_spin_locked(&device_domain_lock);
>  	if (WARN_ON(!info))
> -		return;
> +		return -EINVAL;
>  
> -	list_del(&domain->auxd);
> +	ret = _auxiliary_unlink_device(domain, subinfo, dev);
> +	if (ret == 0) {
> +		list_del(&subinfo->link_domain);
> +		list_del(&subinfo->link_phys);
> +		kfree(subinfo);
> +	}
>  	domain->auxd_refcnt--;
>  
> -	if (!domain->auxd_refcnt && domain->default_pasid > 0)
> -		ioasid_free(domain->default_pasid);
> +	return ret;
>  }
>  
>  static int aux_domain_add_dev(struct dmar_domain *domain,
> @@ -5207,6 +5254,8 @@ static int aux_domain_add_dev(struct dmar_domain
> *domain, int ret;
>  	unsigned long flags;
>  	struct intel_iommu *iommu;
> +	struct device_domain_info *info = get_domain_info(dev);
> +	struct subdevice_domain_info *subinfo;
>  
>  	iommu = device_to_iommu(dev, NULL, NULL);
>  	if (!iommu)
> @@ -5227,6 +5276,12 @@ static int aux_domain_add_dev(struct dmar_domain
> *domain, }
>  
>  	spin_lock_irqsave(&device_domain_lock, flags);
> +	subinfo = subdevice_domain_info_lookup(domain, dev);
> +	if (subinfo) {
> +		_auxiliary_link_device(domain, subinfo, dev);
> +		spin_unlock_irqrestore(&device_domain_lock, flags);
> +		return 0;
> +	}
>  	/*
>  	 * iommu->lock must be held to attach domain to iommu and setup
> the
>  	 * pasid entry for second level translation.
> @@ -5270,6 +5325,7 @@ static void aux_domain_remove_dev(struct
> dmar_domain *domain, struct device_domain_info *info;
>  	struct intel_iommu *iommu;
>  	unsigned long flags;
> +	struct subdevice_domain_info *subinfo;
>  
>  	if (!is_aux_domain(dev, &domain->domain))
>  		return;
> @@ -5278,14 +5334,26 @@ static void aux_domain_remove_dev(struct
> dmar_domain *domain, info = get_domain_info(dev);
>  	iommu = info->iommu;
>  
> -	auxiliary_unlink_device(domain, dev);
> +	subinfo = subdevice_domain_info_lookup(domain, dev);
> +	if (!subinfo) {
> +		spin_unlock_irqrestore(&device_domain_lock, flags);
> +		return;
> +	}
>  
> -	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, subinfo, dev) == 0) {
> +		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 (!domain->auxd_refcnt && domain->default_pasid > 0)
> +		ioasid_free(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..1fb3d6ab719a 100644
> --- a/include/linux/intel-iommu.h
> +++ b/include/linux/intel-iommu.h
> @@ -537,7 +537,7 @@ struct dmar_domain {
>  
>  	bool has_iotlb_device;
>  	struct list_head devices;	/* all devices' list */
> -	struct list_head auxd;		/* link to device's
> auxiliary list */
> +	struct list_head sub_devices;	/* all devices' list
> attached via aux-attach */ struct iova_domain iovad;	/* iova's
> that belong to this domain */ 
>  	struct dma_pte	*pgd;		/* virtual address */
> @@ -636,6 +636,15 @@ struct device_domain_info {
>  	struct pasid_table *pasid_table; /* pasid table */
>  };
>  
> +/* Aux attach device domain info */
> +struct subdevice_domain_info {
> +	struct device *dev;
> +	struct dmar_domain *domain;
> +	struct list_head link_phys;	/* link to phys device
> siblings */
> +	struct list_head link_domain;	/* link to domain siblings
> */
> +	int users;
> +};
> +
>  static inline void __iommu_flush_cache(
>  	struct intel_iommu *iommu, void *addr, int size)
>  {


Thanks,

Jacob
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