Merge tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dledford/rdma

[karo-tx-linux.git] / drivers / vfio / vfio.c

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 6a49485eb49da783a5d7e404de9b3806cbff2524..330d50582f400e7cd93d3242d91270e0d1fdbf66 100644 (file)
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -423,6 +423,34 @@ static void vfio_group_put(struct vfio_group *group)
        kref_put_mutex(&group->kref, vfio_group_release, &vfio.group_lock);
 }
 
+struct vfio_group_put_work {
+       struct work_struct work;
+       struct vfio_group *group;
+};
+
+static void vfio_group_put_bg(struct work_struct *work)
+{
+       struct vfio_group_put_work *do_work;
+
+       do_work = container_of(work, struct vfio_group_put_work, work);
+
+       vfio_group_put(do_work->group);
+       kfree(do_work);
+}
+
+static void vfio_group_schedule_put(struct vfio_group *group)
+{
+       struct vfio_group_put_work *do_work;
+
+       do_work = kmalloc(sizeof(*do_work), GFP_KERNEL);
+       if (WARN_ON(!do_work))
+               return;
+
+       INIT_WORK(&do_work->work, vfio_group_put_bg);
+       do_work->group = group;
+       schedule_work(&do_work->work);
+}
+
 /* Assume group_lock or group reference is held */
 static void vfio_group_get(struct vfio_group *group)
 {
@@ -762,7 +790,14 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
                break;
        }
 
-       vfio_group_put(group);
+       /*
+        * If we're the last reference to the group, the group will be
+        * released, which includes unregistering the iommu group notifier.
+        * We hold a read-lock on that notifier list, unregistering needs
+        * a write-lock... deadlock.  Release our reference asynchronously
+        * to avoid that situation.
+        */
+       vfio_group_schedule_put(group);
        return NOTIFY_OK;
 }
 
@@ -1140,15 +1175,11 @@ static long vfio_fops_unl_ioctl(struct file *filep,
                ret = vfio_ioctl_set_iommu(container, arg);
                break;
        default:
-               down_read(&container->group_lock);
-
                driver = container->iommu_driver;
                data = container->iommu_data;
 
                if (driver) /* passthrough all unrecognized ioctls */
                        ret = driver->ops->ioctl(data, cmd, arg);
-
-               up_read(&container->group_lock);
        }
 
        return ret;
@@ -1202,15 +1233,11 @@ static ssize_t vfio_fops_read(struct file *filep, char __user *buf,
        struct vfio_iommu_driver *driver;
        ssize_t ret = -EINVAL;
 
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->read))
                ret = driver->ops->read(container->iommu_data,
                                        buf, count, ppos);
 
-       up_read(&container->group_lock);
-
        return ret;
 }
 
@@ -1221,15 +1248,11 @@ static ssize_t vfio_fops_write(struct file *filep, const char __user *buf,
        struct vfio_iommu_driver *driver;
        ssize_t ret = -EINVAL;
 
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->write))
                ret = driver->ops->write(container->iommu_data,
                                         buf, count, ppos);
 
-       up_read(&container->group_lock);
-
        return ret;
 }
 
@@ -1239,14 +1262,10 @@ static int vfio_fops_mmap(struct file *filep, struct vm_area_struct *vma)
        struct vfio_iommu_driver *driver;
        int ret = -EINVAL;
 
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->mmap))
                ret = driver->ops->mmap(container->iommu_data, vma);
 
-       up_read(&container->group_lock);
-
        return ret;
 }
 
@@ -1741,6 +1760,15 @@ void vfio_group_put_external_user(struct vfio_group *group)
 }
 EXPORT_SYMBOL_GPL(vfio_group_put_external_user);
 
+bool vfio_external_group_match_file(struct vfio_group *test_group,
+                                   struct file *filep)
+{
+       struct vfio_group *group = filep->private_data;
+
+       return (filep->f_op == &vfio_group_fops) && (group == test_group);
+}
+EXPORT_SYMBOL_GPL(vfio_external_group_match_file);
+
 int vfio_external_user_iommu_id(struct vfio_group *group)
 {
        return iommu_group_id(group->iommu_group);
@@ -1949,8 +1977,6 @@ int vfio_pin_pages(struct device *dev, unsigned long *user_pfn, int npage,
                goto err_pin_pages;
 
        container = group->container;
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->pin_pages))
                ret = driver->ops->pin_pages(container->iommu_data, user_pfn,
@@ -1958,7 +1984,6 @@ int vfio_pin_pages(struct device *dev, unsigned long *user_pfn, int npage,
        else
                ret = -ENOTTY;
 
-       up_read(&container->group_lock);
        vfio_group_try_dissolve_container(group);
 
 err_pin_pages:
@@ -1998,8 +2023,6 @@ int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn, int npage)
                goto err_unpin_pages;
 
        container = group->container;
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->unpin_pages))
                ret = driver->ops->unpin_pages(container->iommu_data, user_pfn,
@@ -2007,7 +2030,6 @@ int vfio_unpin_pages(struct device *dev, unsigned long *user_pfn, int npage)
        else
                ret = -ENOTTY;
 
-       up_read(&container->group_lock);
        vfio_group_try_dissolve_container(group);
 
 err_unpin_pages:
@@ -2029,8 +2051,6 @@ static int vfio_register_iommu_notifier(struct vfio_group *group,
                return -EINVAL;
 
        container = group->container;
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->register_notifier))
                ret = driver->ops->register_notifier(container->iommu_data,
@@ -2038,7 +2058,6 @@ static int vfio_register_iommu_notifier(struct vfio_group *group,
        else
                ret = -ENOTTY;
 
-       up_read(&container->group_lock);
        vfio_group_try_dissolve_container(group);
 
        return ret;
@@ -2056,8 +2075,6 @@ static int vfio_unregister_iommu_notifier(struct vfio_group *group,
                return -EINVAL;
 
        container = group->container;
-       down_read(&container->group_lock);
-
        driver = container->iommu_driver;
        if (likely(driver && driver->ops->unregister_notifier))
                ret = driver->ops->unregister_notifier(container->iommu_data,
@@ -2065,7 +2082,6 @@ static int vfio_unregister_iommu_notifier(struct vfio_group *group,
        else
                ret = -ENOTTY;
 
-       up_read(&container->group_lock);
        vfio_group_try_dissolve_container(group);
 
        return ret;
@@ -2083,7 +2099,6 @@ static int vfio_register_group_notifier(struct vfio_group *group,
                                        unsigned long *events,
                                        struct notifier_block *nb)
 {
-       struct vfio_container *container;
        int ret;
        bool set_kvm = false;
 
@@ -2101,9 +2116,6 @@ static int vfio_register_group_notifier(struct vfio_group *group,
        if (ret)
                return -EINVAL;
 
-       container = group->container;
-       down_read(&container->group_lock);
-
        ret = blocking_notifier_chain_register(&group->notifier, nb);
 
        /*
@@ -2114,7 +2126,6 @@ static int vfio_register_group_notifier(struct vfio_group *group,
                blocking_notifier_call_chain(&group->notifier,
                                        VFIO_GROUP_NOTIFY_SET_KVM, group->kvm);
 
-       up_read(&container->group_lock);
        vfio_group_try_dissolve_container(group);
 
        return ret;
@@ -2123,19 +2134,14 @@ static int vfio_register_group_notifier(struct vfio_group *group,
 static int vfio_unregister_group_notifier(struct vfio_group *group,
                                         struct notifier_block *nb)
 {
-       struct vfio_container *container;
        int ret;
 
        ret = vfio_group_add_container_user(group);
        if (ret)
                return -EINVAL;
 
-       container = group->container;
-       down_read(&container->group_lock);
-
        ret = blocking_notifier_chain_unregister(&group->notifier, nb);
 
-       up_read(&container->group_lock);
        vfio_group_try_dissolve_container(group);
 
        return ret;