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SubjectRe: [PATCH RFC v2 08/11] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces
Hi Lu,

On Tue, 29 Mar 2022 13:37:57 +0800, Lu Baolu <baolu.lu@linux.intel.com>
wrote:

> The existing iommu SVA interfaces are implemented by calling the SVA
> specific iommu ops provided by the IOMMU drivers. There's no need for
> any SVA specific ops in iommu_ops vector anymore as we can achieve
> this through the generic attach/detach_dev_pasid domain ops.
>
> This refactors the IOMMU SVA interfaces implementation by using the
> attach/detach_pasid_dev ops and align them with the concept of the
> iommu domain. Put the new SVA code in the sva related file in order
> to make it self-contained.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
> include/linux/iommu.h | 51 +++++++++-------
> drivers/iommu/iommu-sva-lib.c | 110 +++++++++++++++++++++++++++++++++-
> drivers/iommu/iommu.c | 92 ----------------------------
> 3 files changed, 138 insertions(+), 115 deletions(-)
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> index a46285488a57..11c4d99e122d 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -629,7 +629,12 @@ struct iommu_fwspec {
> * struct iommu_sva - handle to a device-mm bond
> */
> struct iommu_sva {
> - struct device *dev;
> + struct device *dev;
> + ioasid_t pasid;
> + struct iommu_domain *domain;
> + /* Link to sva domain's bonds list */
> + struct list_head node;
> + refcount_t users;
> };
>
> int iommu_fwspec_init(struct device *dev, struct fwnode_handle
> *iommu_fwnode, @@ -672,12 +677,6 @@ int iommu_dev_enable_feature(struct
> device *dev, enum iommu_dev_features f); int
> iommu_dev_disable_feature(struct device *dev, enum iommu_dev_features f);
> bool iommu_dev_feature_enabled(struct device *dev, enum
> iommu_dev_features f); -struct iommu_sva *iommu_sva_bind_device(struct
> device *dev,
> - struct mm_struct *mm,
> - void *drvdata);
> -void iommu_sva_unbind_device(struct iommu_sva *handle);
> -u32 iommu_sva_get_pasid(struct iommu_sva *handle);
> -
> int iommu_device_use_default_domain(struct device *dev);
> void iommu_device_unuse_default_domain(struct device *dev);
>
> @@ -1018,21 +1017,6 @@ iommu_dev_disable_feature(struct device *dev, enum
> iommu_dev_features feat) return -ENODEV;
> }
>
> -static inline struct iommu_sva *
> -iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata) -{
> - return NULL;
> -}
> -
> -static inline void iommu_sva_unbind_device(struct iommu_sva *handle)
> -{
> -}
> -
> -static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> -{
> - return IOMMU_PASID_INVALID;
> -}
> -
> static inline struct iommu_fwspec *dev_iommu_fwspec_get(struct device
> *dev) {
> return NULL;
> @@ -1085,6 +1069,29 @@ iommu_put_domain_for_dev_pasid(struct iommu_domain
> *domain) }
> #endif /* CONFIG_IOMMU_API */
>
> +#ifdef CONFIG_IOMMU_SVA
> +struct iommu_sva *iommu_sva_bind_device(struct device *dev,
> + struct mm_struct *mm,
> + void *drvdata);
> +void iommu_sva_unbind_device(struct iommu_sva *handle);
> +u32 iommu_sva_get_pasid(struct iommu_sva *handle);
> +#else /* CONFIG_IOMMU_SVA */
> +static inline struct iommu_sva *
> +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata) +{
> + return NULL;
> +}
> +
> +static inline void iommu_sva_unbind_device(struct iommu_sva *handle)
> +{
> +}
> +
> +static inline u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> +{
> + return IOMMU_PASID_INVALID;
> +}
> +#endif /* CONFIG_IOMMU_SVA */
> +
> /**
> * iommu_map_sgtable - Map the given buffer to the IOMMU domain
> * @domain: The IOMMU domain to perform the mapping
> diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
> index 78820be23f15..1b45b7d01836 100644
> --- a/drivers/iommu/iommu-sva-lib.c
> +++ b/drivers/iommu/iommu-sva-lib.c
> @@ -17,6 +17,7 @@ struct iommu_sva_cookie {
> struct mm_struct *mm;
> ioasid_t pasid;
> refcount_t users;
> + struct list_head bonds;
> };
>
> /**
> @@ -101,6 +102,7 @@ iommu_sva_alloc_domain(struct device *dev, struct
> mm_struct *mm) cookie->mm = mm;
> cookie->pasid = mm->pasid;
> refcount_set(&cookie->users, 1);
> + INIT_LIST_HEAD(&cookie->bonds);
> domain->type = IOMMU_DOMAIN_SVA;
> domain->sva_cookie = cookie;
> curr = xa_store(&sva_domain_array, mm->pasid, domain,
> GFP_KERNEL); @@ -118,6 +120,7 @@ iommu_sva_alloc_domain(struct device
> *dev, struct mm_struct *mm) static void iommu_sva_free_domain(struct
> iommu_domain *domain) {
> xa_erase(&sva_domain_array, domain->sva_cookie->pasid);
> + WARN_ON(!list_empty(&domain->sva_cookie->bonds));
> kfree(domain->sva_cookie);
> domain->ops->free(domain);
> }
> @@ -137,7 +140,7 @@ void iommu_sva_domain_put_user(struct iommu_domain
> *domain) iommu_sva_free_domain(domain);
> }
>
> -static __maybe_unused struct iommu_domain *
> +static struct iommu_domain *
> iommu_sva_get_domain(struct device *dev, struct mm_struct *mm)
> {
> struct iommu_domain *domain;
> @@ -158,3 +161,108 @@ struct mm_struct *iommu_sva_domain_mm(struct
> iommu_domain *domain) {
> return domain->sva_cookie->mm;
> }
> +
> +/**
> + * iommu_sva_bind_device() - Bind a process address space to a device
> + * @dev: the device
> + * @mm: the mm to bind, caller must hold a reference to it
> + * @drvdata: opaque data pointer to pass to bind callback
> + *
> + * Create a bond between device and address space, allowing the device
> to access
> + * the mm using the returned PASID. If a bond already exists between
> @device and
> + * @mm, it is returned and an additional reference is taken. Caller must
> call
> + * iommu_sva_unbind_device() to release each reference.
> + *
> + * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called
> first, to
> + * initialize the required SVA features.
> + *
> + * On error, returns an ERR_PTR value.
> + */
> +struct iommu_sva *
> +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata) +{
> + int ret = -EINVAL;
> + struct iommu_sva *handle;
> + struct iommu_domain *domain;
> +
> + ret = iommu_sva_alloc_pasid(mm, 1, (1U <<
> dev->iommu->pasid_bits) - 1);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + mutex_lock(&iommu_sva_lock);
> + domain = iommu_sva_get_domain(dev, mm);
> + if (!domain) {
> + ret = -ENOMEM;
> + goto out_unlock;
> + }
> +
> + /* Search for an existing bond. */
> + list_for_each_entry(handle, &domain->sva_cookie->bonds, node) {
> + if (handle->dev == dev && handle->pasid == mm->pasid) {
> + refcount_inc(&handle->users);
> + mutex_lock(&iommu_sva_lock);
> +
> + return handle;
> + }
> + }
> +
> + handle = kzalloc(sizeof(*handle), GFP_KERNEL);
> + if (!handle) {
> + ret = -ENOMEM;
> + goto out_put_domain;
> + }
> +
> + ret = iommu_attach_device_pasid(domain, dev, mm->pasid);
> + if (ret)
> + goto out_free_handle;
> +
> + handle->dev = dev;
> + handle->domain = domain;
> + handle->pasid = mm->pasid;
why do we need to store pasid here? Conceptually, pasid is per sva domain
not per bind. You can get it from handle->domain->sva_cookie.

> + refcount_set(&handle->users, 1);
> + list_add_tail(&handle->node, &domain->sva_cookie->bonds);
> +
> + mutex_unlock(&iommu_sva_lock);
> + return handle;
> +
> +out_free_handle:
> + kfree(handle);
> +out_put_domain:
> + iommu_sva_domain_put_user(domain);
> +out_unlock:
> + mutex_unlock(&iommu_sva_lock);
> + return ERR_PTR(ret);
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
> +
> +/**
> + * iommu_sva_unbind_device() - Remove a bond created with
> iommu_sva_bind_device
> + * @handle: the handle returned by iommu_sva_bind_device()
> + *
> + * Put reference to a bond between device and address space. The device
> should
> + * not be issuing any more transaction for this PASID. All outstanding
> page
> + * requests for this PASID must have been flushed to the IOMMU.
> + */
> +void iommu_sva_unbind_device(struct iommu_sva *handle)
> +{
> + struct device *dev = handle->dev;
> + struct iommu_domain *domain = handle->domain;
> + struct mm_struct *mm = iommu_sva_domain_mm(domain);
> +
> + mutex_lock(&iommu_sva_lock);
> + if (refcount_dec_and_test(&handle->users)) {
> + list_del(&handle->node);
> + iommu_detach_device_pasid(domain, dev, mm->pasid);
> + kfree(handle);
> + }
> +
> + iommu_sva_domain_put_user(domain);
> + mutex_unlock(&iommu_sva_lock);
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
> +
> +u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> +{
> + return handle->pasid;
> +}
> +EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 8163ad7f6902..6b51ead9d63b 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -2712,98 +2712,6 @@ bool iommu_dev_feature_enabled(struct device *dev,
> enum iommu_dev_features feat) }
> EXPORT_SYMBOL_GPL(iommu_dev_feature_enabled);
>
> -/**
> - * iommu_sva_bind_device() - Bind a process address space to a device
> - * @dev: the device
> - * @mm: the mm to bind, caller must hold a reference to it
> - * @drvdata: opaque data pointer to pass to bind callback
> - *
> - * Create a bond between device and address space, allowing the device
> to access
> - * the mm using the returned PASID. If a bond already exists between
> @device and
> - * @mm, it is returned and an additional reference is taken. Caller must
> call
> - * iommu_sva_unbind_device() to release each reference.
> - *
> - * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called
> first, to
> - * initialize the required SVA features.
> - *
> - * On error, returns an ERR_PTR value.
> - */
> -struct iommu_sva *
> -iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void
> *drvdata) -{
> - struct iommu_group *group;
> - struct iommu_sva *handle = ERR_PTR(-EINVAL);
> - const struct iommu_ops *ops = dev_iommu_ops(dev);
> -
> - if (!ops->sva_bind)
> - return ERR_PTR(-ENODEV);
> -
> - group = iommu_group_get(dev);
> - if (!group)
> - return ERR_PTR(-ENODEV);
> -
> - /* Ensure device count and domain don't change while we're
> binding */
> - mutex_lock(&group->mutex);
> -
> - /*
> - * To keep things simple, SVA currently doesn't support IOMMU
> groups
> - * with more than one device. Existing SVA-capable systems are
> not
> - * affected by the problems that required IOMMU groups (lack of
> ACS
> - * isolation, device ID aliasing and other hardware issues).
> - */
> - if (!iommu_group_singleton_lockdown(group))
> - goto out_unlock;
> -
> - handle = ops->sva_bind(dev, mm, drvdata);
> -
> -out_unlock:
> - mutex_unlock(&group->mutex);
> - iommu_group_put(group);
> -
> - return handle;
> -}
> -EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
> -
> -/**
> - * iommu_sva_unbind_device() - Remove a bond created with
> iommu_sva_bind_device
> - * @handle: the handle returned by iommu_sva_bind_device()
> - *
> - * Put reference to a bond between device and address space. The device
> should
> - * not be issuing any more transaction for this PASID. All outstanding
> page
> - * requests for this PASID must have been flushed to the IOMMU.
> - */
> -void iommu_sva_unbind_device(struct iommu_sva *handle)
> -{
> - struct iommu_group *group;
> - struct device *dev = handle->dev;
> - const struct iommu_ops *ops = dev_iommu_ops(dev);
> -
> - if (!ops->sva_unbind)
> - return;
> -
> - group = iommu_group_get(dev);
> - if (!group)
> - return;
> -
> - mutex_lock(&group->mutex);
> - ops->sva_unbind(handle);
> - mutex_unlock(&group->mutex);
> -
> - iommu_group_put(group);
> -}
> -EXPORT_SYMBOL_GPL(iommu_sva_unbind_device);
> -
> -u32 iommu_sva_get_pasid(struct iommu_sva *handle)
> -{
> - const struct iommu_ops *ops = dev_iommu_ops(handle->dev);
> -
> - if (!ops->sva_get_pasid)
> - return IOMMU_PASID_INVALID;
> -
> - return ops->sva_get_pasid(handle);
> -}
> -EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
> -
> /*
> * Changes the default domain of an iommu group that has *only* one
> device *


Thanks,

Jacob

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