Re: [PATCH v3 2/4] iommu: Add iommu_aux_at(de)tach_group()

Jacob Pan
2020-07-14T16:32:54Z

On Tue, 14 Jul 2020 13:57:01 +0800
Lu Baolu <baolu.lu@linux.intel.com> wrote:

> This adds two new aux-domain APIs for a use case like vfio/mdev where
> sub-devices derived from an aux-domain capable device are created and
> put in an iommu_group.
>
> /**
> * iommu_aux_attach_group - attach an aux-domain to an iommu_group
> which
> * contains sub-devices (for example mdevs)
> derived
> * from @dev.
> * @domain: an aux-domain;
> * @group: an iommu_group which contains sub-devices derived from
> @dev;
> * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
> *
> * Returns 0 on success, or an error value.
> */
> int iommu_aux_attach_group(struct iommu_domain *domain,
> struct iommu_group *group,
> struct device *dev)
>
> /**
> * iommu_aux_detach_group - detach an aux-domain from an iommu_group
> *
> * @domain: an aux-domain;
> * @group: an iommu_group which contains sub-devices derived from
> @dev;
> * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
> *
> * @domain must have been attached to @group via
> iommu_aux_attach_group(). */
> void iommu_aux_detach_group(struct iommu_domain *domain,
> struct iommu_group *group,
> struct device *dev)
>
> It also adds a flag in the iommu_group data structure to identify
> an iommu_group with aux-domain attached from those normal ones.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
> drivers/iommu/iommu.c | 58
> +++++++++++++++++++++++++++++++++++++++++++ include/linux/iommu.h |
> 17 +++++++++++++ 2 files changed, 75 insertions(+)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index e1fdd3531d65..cad5a19ebf22 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -45,6 +45,7 @@ struct iommu_group {
> struct iommu_domain *default_domain;
> struct iommu_domain *domain;
> struct list_head entry;
> + unsigned int aux_domain_attached:1;
> };
>
> struct group_device {
> @@ -2759,6 +2760,63 @@ int iommu_aux_get_pasid(struct iommu_domain
> *domain, struct device *dev) }
> EXPORT_SYMBOL_GPL(iommu_aux_get_pasid);
>
> +/**
> + * iommu_aux_attach_group - attach an aux-domain to an iommu_group
> which
> + * contains sub-devices (for example mdevs)
> derived
> + * from @dev.
> + * @domain: an aux-domain;
> + * @group: an iommu_group which contains sub-devices derived from
> @dev;
> + * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
> + *
> + * Returns 0 on success, or an error value.
> + */
> +int iommu_aux_attach_group(struct iommu_domain *domain,
> + struct iommu_group *group, struct device
> *dev) +{
> + int ret = -EBUSY;
> +
> + mutex_lock(&group->mutex);
> + if (group->domain)
> + goto out_unlock;
> +
Perhaps I missed something but are we assuming only one mdev per mdev
group? That seems to change the logic where vfio does:
iommu_group_for_each_dev()
iommu_aux_attach_device()

> + ret = iommu_aux_attach_device(domain, dev);
> + if (!ret) {
> + group->domain = domain;
> + group->aux_domain_attached = true;
> + }
> +
> +out_unlock:
> + mutex_unlock(&group->mutex);
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(iommu_aux_attach_group);
> +
> +/**
> + * iommu_aux_detach_group - detach an aux-domain from an iommu_group
> + *
> + * @domain: an aux-domain;
> + * @group: an iommu_group which contains sub-devices derived from
> @dev;
> + * @dev: the physical device which supports IOMMU_DEV_FEAT_AUX.
> + *
> + * @domain must have been attached to @group via
> iommu_aux_attach_group().
> + */
> +void iommu_aux_detach_group(struct iommu_domain *domain,
> + struct iommu_group *group, struct device
> *dev) +{
> + mutex_lock(&group->mutex);
> +
> + if (WARN_ON(!group->aux_domain_attached || group->domain !=
> domain))
> + goto out_unlock;
> +
> + iommu_aux_detach_device(domain, dev);
> + group->aux_domain_attached = false;
> + group->domain = NULL;
> +
> +out_unlock:
> + mutex_unlock(&group->mutex);
> +}
> +EXPORT_SYMBOL_GPL(iommu_aux_detach_group);
> +
> /**
> * iommu_sva_bind_device() - Bind a process address space to a device
> * @dev: the device
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index 5657d4fef9f2..9506551139ab 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -635,6 +635,10 @@ bool iommu_dev_feature_enabled(struct device
> *dev, enum iommu_dev_features f); int iommu_aux_attach_device(struct
> iommu_domain *domain, struct device *dev); void
> iommu_aux_detach_device(struct iommu_domain *domain, struct device
> *dev); int iommu_aux_get_pasid(struct iommu_domain *domain, struct
> device *dev); +int iommu_aux_attach_group(struct iommu_domain *domain,
> + struct iommu_group *group, struct device
> *dev); +void iommu_aux_detach_group(struct iommu_domain *domain,
> + struct iommu_group *group, struct device
> *dev);
> struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> struct mm_struct *mm,
> @@ -1023,6 +1027,19 @@ iommu_aux_get_pasid(struct iommu_domain
> *domain, struct device *dev) return -ENODEV;
> }
>
> +static inline int
> +iommu_aux_attach_group(struct iommu_domain *domain,
> + struct iommu_group *group, struct device *dev)
> +{
> + return -ENODEV;
> +}
> +
> +static inline void
> +iommu_aux_detach_group(struct iommu_domain *domain,
> + struct iommu_group *group, struct device *dev)
> +{
> +}
> +
> static inline struct iommu_sva *
> iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata) {

[Jacob Pan]