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iommufd: Add iommufd_access_change_ioas(_id) helpers
The complication of the mutex and refcount will be amplified after we introduce the replace support for accesses. So, add a preparatory change of a constitutive helper iommufd_access_change_ioas() and its wrapper iommufd_access_change_ioas_id(). They can simply take care of existing iommufd_access_attach() and iommufd_access_detach(), properly sequencing the refcount puts so that they are truely at the end of the sequence after we know the IOAS pointer is not required any more. Link: https://lore.kernel.org/r/da0c462532193b447329c4eb975a596f47e49b70.1690523699.git.nicolinc@nvidia.com Suggested-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Kevin Tian <kevin.tian@intel.com> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
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5d5c85ff62
commit
9227da7816
1 changed files with 71 additions and 38 deletions
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@ -684,6 +684,70 @@ void iommufd_device_detach(struct iommufd_device *idev)
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}
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}
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EXPORT_SYMBOL_NS_GPL(iommufd_device_detach, IOMMUFD);
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EXPORT_SYMBOL_NS_GPL(iommufd_device_detach, IOMMUFD);
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/*
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* On success, it will refcount_inc() at a valid new_ioas and refcount_dec() at
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* a valid cur_ioas (access->ioas). A caller passing in a valid new_ioas should
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* call iommufd_put_object() if it does an iommufd_get_object() for a new_ioas.
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*/
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static int iommufd_access_change_ioas(struct iommufd_access *access,
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struct iommufd_ioas *new_ioas)
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{
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u32 iopt_access_list_id = access->iopt_access_list_id;
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struct iommufd_ioas *cur_ioas = access->ioas;
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int rc;
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lockdep_assert_held(&access->ioas_lock);
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/* We are racing with a concurrent detach, bail */
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if (cur_ioas != access->ioas_unpin)
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return -EBUSY;
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if (cur_ioas == new_ioas)
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return 0;
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/*
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* Set ioas to NULL to block any further iommufd_access_pin_pages().
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* iommufd_access_unpin_pages() can continue using access->ioas_unpin.
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*/
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access->ioas = NULL;
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if (new_ioas) {
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rc = iopt_add_access(&new_ioas->iopt, access);
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if (rc) {
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access->ioas = cur_ioas;
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return rc;
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}
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refcount_inc(&new_ioas->obj.users);
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}
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if (cur_ioas) {
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if (access->ops->unmap) {
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mutex_unlock(&access->ioas_lock);
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access->ops->unmap(access->data, 0, ULONG_MAX);
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mutex_lock(&access->ioas_lock);
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}
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iopt_remove_access(&cur_ioas->iopt, access, iopt_access_list_id);
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refcount_dec(&cur_ioas->obj.users);
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}
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access->ioas = new_ioas;
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access->ioas_unpin = new_ioas;
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return 0;
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}
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static int iommufd_access_change_ioas_id(struct iommufd_access *access, u32 id)
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{
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struct iommufd_ioas *ioas = iommufd_get_ioas(access->ictx, id);
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int rc;
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if (IS_ERR(ioas))
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return PTR_ERR(ioas);
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rc = iommufd_access_change_ioas(access, ioas);
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iommufd_put_object(&ioas->obj);
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return rc;
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}
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void iommufd_access_destroy_object(struct iommufd_object *obj)
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void iommufd_access_destroy_object(struct iommufd_object *obj)
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{
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{
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struct iommufd_access *access =
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struct iommufd_access *access =
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@ -761,60 +825,29 @@ EXPORT_SYMBOL_NS_GPL(iommufd_access_destroy, IOMMUFD);
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void iommufd_access_detach(struct iommufd_access *access)
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void iommufd_access_detach(struct iommufd_access *access)
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{
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{
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struct iommufd_ioas *cur_ioas = access->ioas;
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mutex_lock(&access->ioas_lock);
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mutex_lock(&access->ioas_lock);
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if (WARN_ON(!access->ioas))
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if (WARN_ON(!access->ioas)) {
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goto out;
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/*
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* Set ioas to NULL to block any further iommufd_access_pin_pages().
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* iommufd_access_unpin_pages() can continue using access->ioas_unpin.
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*/
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access->ioas = NULL;
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if (access->ops->unmap) {
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mutex_unlock(&access->ioas_lock);
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mutex_unlock(&access->ioas_lock);
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access->ops->unmap(access->data, 0, ULONG_MAX);
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return;
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mutex_lock(&access->ioas_lock);
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}
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}
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iopt_remove_access(&cur_ioas->iopt, access,
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WARN_ON(iommufd_access_change_ioas(access, NULL));
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access->iopt_access_list_id);
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refcount_dec(&cur_ioas->obj.users);
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out:
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access->ioas_unpin = NULL;
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mutex_unlock(&access->ioas_lock);
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mutex_unlock(&access->ioas_lock);
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}
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}
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EXPORT_SYMBOL_NS_GPL(iommufd_access_detach, IOMMUFD);
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EXPORT_SYMBOL_NS_GPL(iommufd_access_detach, IOMMUFD);
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int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id)
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int iommufd_access_attach(struct iommufd_access *access, u32 ioas_id)
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{
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{
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struct iommufd_ioas *new_ioas;
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int rc;
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int rc = 0;
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mutex_lock(&access->ioas_lock);
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mutex_lock(&access->ioas_lock);
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if (WARN_ON(access->ioas || access->ioas_unpin)) {
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if (WARN_ON(access->ioas)) {
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mutex_unlock(&access->ioas_lock);
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mutex_unlock(&access->ioas_lock);
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return -EINVAL;
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return -EINVAL;
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}
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}
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new_ioas = iommufd_get_ioas(access->ictx, ioas_id);
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rc = iommufd_access_change_ioas_id(access, ioas_id);
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if (IS_ERR(new_ioas)) {
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mutex_unlock(&access->ioas_lock);
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return PTR_ERR(new_ioas);
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}
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rc = iopt_add_access(&new_ioas->iopt, access);
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if (rc) {
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mutex_unlock(&access->ioas_lock);
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iommufd_put_object(&new_ioas->obj);
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return rc;
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}
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iommufd_ref_to_users(&new_ioas->obj);
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access->ioas = new_ioas;
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access->ioas_unpin = new_ioas;
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mutex_unlock(&access->ioas_lock);
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mutex_unlock(&access->ioas_lock);
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return 0;
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return rc;
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}
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}
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EXPORT_SYMBOL_NS_GPL(iommufd_access_attach, IOMMUFD);
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EXPORT_SYMBOL_NS_GPL(iommufd_access_attach, IOMMUFD);
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