}
static bool vq_access_ok(struct vhost_virtqueue *vq, unsigned int num,
- struct vring_desc __user *desc,
- struct vring_avail __user *avail,
- struct vring_used __user *used)
+ vring_desc_t __user *desc,
+ vring_avail_t __user *avail,
+ vring_used_t __user *used)
{
return access_ok(desc, vhost_get_desc_size(vq, num)) &&
struct vring_used_elem *heads,
unsigned count)
{
- struct vring_used_elem __user *used;
+ vring_used_elem_t __user *used;
u16 old, new;
int start;
/* The actual ring of buffers. */
struct mutex mutex;
unsigned int num;
- struct vring_desc __user *desc;
- struct vring_avail __user *avail;
- struct vring_used __user *used;
+ vring_desc_t __user *desc;
+ vring_avail_t __user *avail;
+ vring_used_t __user *used;
const struct vhost_iotlb_map *meta_iotlb[VHOST_NUM_ADDRS];
struct file *kick;
struct eventfd_ctx *call_ctx;
*/
int vringh_init_user(struct vringh *vrh, u64 features,
unsigned int num, bool weak_barriers,
- struct vring_desc __user *desc,
- struct vring_avail __user *avail,
- struct vring_used __user *used)
+ vring_desc_t __user *desc,
+ vring_avail_t __user *avail,
+ vring_used_t __user *used)
{
/* Sane power of 2 please! */
if (!num || num > 0xffff || (num & (num - 1))) {
/* Helpers for userspace vrings. */
int vringh_init_user(struct vringh *vrh, u64 features,
unsigned int num, bool weak_barriers,
- struct vring_desc __user *desc,
- struct vring_avail __user *avail,
- struct vring_used __user *used);
+ vring_desc_t __user *desc,
+ vring_avail_t __user *avail,
+ vring_used_t __user *used);
static inline void vringh_iov_init(struct vringh_iov *iov,
struct iovec *iovec, unsigned num)
* at the end of the used ring. Guest should ignore the used->flags field. */
#define VIRTIO_RING_F_EVENT_IDX 29
+/* Alignment requirements for vring elements.
+ * When using pre-virtio 1.0 layout, these fall out naturally.
+ */
+#define VRING_AVAIL_ALIGN_SIZE 2
+#define VRING_USED_ALIGN_SIZE 4
+#define VRING_DESC_ALIGN_SIZE 16
+
/* Virtio ring descriptors: 16 bytes. These can chain together via "next". */
struct vring_desc {
/* Address (guest-physical). */
__virtio32 len;
};
+typedef struct vring_used_elem __attribute__((aligned(VRING_USED_ALIGN_SIZE)))
+ vring_used_elem_t;
+
struct vring_used {
__virtio16 flags;
__virtio16 idx;
- struct vring_used_elem ring[];
+ vring_used_elem_t ring[];
};
+/*
+ * The ring element addresses are passed between components with different
+ * alignments assumptions. Thus, we might need to decrease the compiler-selected
+ * alignment, and so must use a typedef to make sure the aligned attribute
+ * actually takes hold:
+ *
+ * https://gcc.gnu.org/onlinedocs//gcc/Common-Type-Attributes.html#Common-Type-Attributes
+ *
+ * When used on a struct, or struct member, the aligned attribute can only
+ * increase the alignment; in order to decrease it, the packed attribute must
+ * be specified as well. When used as part of a typedef, the aligned attribute
+ * can both increase and decrease alignment, and specifying the packed
+ * attribute generates a warning.
+ */
+typedef struct vring_desc __attribute__((aligned(VRING_DESC_ALIGN_SIZE)))
+ vring_desc_t;
+typedef struct vring_avail __attribute__((aligned(VRING_AVAIL_ALIGN_SIZE)))
+ vring_avail_t;
+typedef struct vring_used __attribute__((aligned(VRING_USED_ALIGN_SIZE)))
+ vring_used_t;
+
struct vring {
unsigned int num;
- struct vring_desc *desc;
+ vring_desc_t *desc;
- struct vring_avail *avail;
+ vring_avail_t *avail;
- struct vring_used *used;
+ vring_used_t *used;
};
-/* Alignment requirements for vring elements.
- * When using pre-virtio 1.0 layout, these fall out naturally.
- */
-#define VRING_AVAIL_ALIGN_SIZE 2
-#define VRING_USED_ALIGN_SIZE 4
-#define VRING_DESC_ALIGN_SIZE 16
-
#ifndef VIRTIO_RING_NO_LEGACY
/* The standard layout for the ring is a continuous chunk of memory which looks