[PATCH v2 1/3] VFIO: unregister IOMMU notifier on error recovery path

[PATCH v2 1/3] VFIO: unregister IOMMU notifier on error recovery path

[Jiang Liu]

On error recovery path in function vfio_create_group(), it should
unregister the IOMMU notifier for the new VFIO group. Otherwise it may
cause invalid memory access later when handling bus notifications.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 drivers/vfio/vfio.c |   31 +++++++++++++++----------------
 1 file changed, 15 insertions(+), 16 deletions(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 17830c9..3359ec2 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -191,6 +191,17 @@ static void vfio_container_put(struct vfio_container *container)
 	kref_put(&container->kref, vfio_container_release);
 }
 
+static void vfio_group_unlock_and_free(struct vfio_group *group)
+{
+	mutex_unlock(&vfio.group_lock);
+	/*
+	 * Unregister outside of lock.  A spurious callback is harmless now
+	 * that the group is no longer in vfio.group_list.
+	 */
+	iommu_group_unregister_notifier(group->iommu_group, &group->nb);
+	kfree(group);
+}
+
 /**
  * Group objects - create, release, get, put, search
  */
@@ -229,8 +240,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 
 	minor = vfio_alloc_group_minor(group);
 	if (minor < 0) {
-		mutex_unlock(&vfio.group_lock);
-		kfree(group);
+		vfio_group_unlock_and_free(group);
 		return ERR_PTR(minor);
 	}
 
@@ -239,8 +249,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 		if (tmp->iommu_group == iommu_group) {
 			vfio_group_get(tmp);
 			vfio_free_group_minor(minor);
-			mutex_unlock(&vfio.group_lock);
-			kfree(group);
+			vfio_group_unlock_and_free(group);
 			return tmp;
 		}
 	}
@@ -249,8 +258,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
 			    group, "%d", iommu_group_id(iommu_group));
 	if (IS_ERR(dev)) {
 		vfio_free_group_minor(minor);
-		mutex_unlock(&vfio.group_lock);
-		kfree(group);
+		vfio_group_unlock_and_free(group);
 		return (struct vfio_group *)dev; /* ERR_PTR */
 	}
 
@@ -274,16 +282,7 @@ static void vfio_group_release(struct kref *kref)
 	device_destroy(vfio.class, MKDEV(MAJOR(vfio.devt), group->minor));
 	list_del(&group->vfio_next);
 	vfio_free_group_minor(group->minor);
-
-	mutex_unlock(&vfio.group_lock);
-
-	/*
-	 * Unregister outside of lock.  A spurious callback is harmless now
-	 * that the group is no longer in vfio.group_list.
-	 */
-	iommu_group_unregister_notifier(group->iommu_group, &group->nb);
-
-	kfree(group);
+	vfio_group_unlock_and_free(group);
 }
 
 static void vfio_group_put(struct vfio_group *group)
-- 
1.7.9.5

[PATCH v2 2/3] VFIO: use ACCESS_ONCE() to guard access to dev->driver

[Jiang Liu]

Comments from dev_driver_string(),
/* dev->driver can change to NULL underneath us because of unbinding,
 * so be careful about accessing it.
 */

So use ACCESS_ONCE() to guard access to dev->driver field.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 drivers/vfio/vfio.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 3359ec2..0090212 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -465,8 +465,9 @@ static int vfio_dev_viable(struct device *dev, void *data)
 {
 	struct vfio_group *group = data;
 	struct vfio_device *device;
+	struct device_driver *drv = ACCESS_ONCE(dev->driver);
 
-	if (!dev->driver || vfio_whitelisted_driver(dev->driver))
+	if (!drv || vfio_whitelisted_driver(drv))
 		return 0;
 
 	device = vfio_group_get_device(group, dev);
-- 
1.7.9.5

[PATCH v2 3/3] VFIO: fix out of order labels for error recovery in vfio_pci_init()

[Jiang Liu]

The two labels for error recovery in function vfio_pci_init() is out of
order, so fix it.

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
---
 drivers/vfio/pci/vfio_pci.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 6968b72..d07fb7e 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -563,9 +563,9 @@ static int __init vfio_pci_init(void)
 
 	return 0;
 
-out_virqfd:
-	vfio_pci_virqfd_exit();
 out_driver:
+	vfio_pci_virqfd_exit();
+out_virqfd:
 	vfio_pci_uninit_perm_bits();
 	return ret;
 }
-- 
1.7.9.5

Re: [PATCH v2 1/3] VFIO: unregister IOMMU notifier on error recovery path

[Alex Williamson]

On Fri, 2012-11-16 at 00:43 +0800, Jiang Liu wrote:
> On error recovery path in function vfio_create_group(), it should
> unregister the IOMMU notifier for the new VFIO group. Otherwise it may
> cause invalid memory access later when handling bus notifications.
> 
> Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
> ---
>  drivers/vfio/vfio.c |   31 +++++++++++++++----------------
>  1 file changed, 15 insertions(+), 16 deletions(-)


Applied all 3, thanks!

Alex

> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index 17830c9..3359ec2 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -191,6 +191,17 @@ static void vfio_container_put(struct vfio_container *container)
>  	kref_put(&container->kref, vfio_container_release);
>  }
>  
> +static void vfio_group_unlock_and_free(struct vfio_group *group)
> +{
> +	mutex_unlock(&vfio.group_lock);
> +	/*
> +	 * Unregister outside of lock.  A spurious callback is harmless now
> +	 * that the group is no longer in vfio.group_list.
> +	 */
> +	iommu_group_unregister_notifier(group->iommu_group, &group->nb);
> +	kfree(group);
> +}
> +
>  /**
>   * Group objects - create, release, get, put, search
>   */
> @@ -229,8 +240,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
>  
>  	minor = vfio_alloc_group_minor(group);
>  	if (minor < 0) {
> -		mutex_unlock(&vfio.group_lock);
> -		kfree(group);
> +		vfio_group_unlock_and_free(group);
>  		return ERR_PTR(minor);
>  	}
>  
> @@ -239,8 +249,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
>  		if (tmp->iommu_group == iommu_group) {
>  			vfio_group_get(tmp);
>  			vfio_free_group_minor(minor);
> -			mutex_unlock(&vfio.group_lock);
> -			kfree(group);
> +			vfio_group_unlock_and_free(group);
>  			return tmp;
>  		}
>  	}
> @@ -249,8 +258,7 @@ static struct vfio_group *vfio_create_group(struct iommu_group *iommu_group)
>  			    group, "%d", iommu_group_id(iommu_group));
>  	if (IS_ERR(dev)) {
>  		vfio_free_group_minor(minor);
> -		mutex_unlock(&vfio.group_lock);
> -		kfree(group);
> +		vfio_group_unlock_and_free(group);
>  		return (struct vfio_group *)dev; /* ERR_PTR */
>  	}
>  
> @@ -274,16 +282,7 @@ static void vfio_group_release(struct kref *kref)
>  	device_destroy(vfio.class, MKDEV(MAJOR(vfio.devt), group->minor));
>  	list_del(&group->vfio_next);
>  	vfio_free_group_minor(group->minor);
> -
> -	mutex_unlock(&vfio.group_lock);
> -
> -	/*
> -	 * Unregister outside of lock.  A spurious callback is harmless now
> -	 * that the group is no longer in vfio.group_list.
> -	 */
> -	iommu_group_unregister_notifier(group->iommu_group, &group->nb);
> -
> -	kfree(group);
> +	vfio_group_unlock_and_free(group);
>  }
>  
>  static void vfio_group_put(struct vfio_group *group)