[Qemu-devel] [PATCH 1/8] virtio: feature bit, data structure for packed ring

[wexu@redhat.com]

From: Wei Xu <wexu@redhat.com>

Only minimum definitions from the spec are included
for prototype.

Signed-off-by: Wei Xu <wexu@redhat.com>
---
 hw/virtio/virtio.c                             | 47 +++++++++++++++++++++++---
 include/hw/virtio/virtio.h                     | 12 ++++++-
 include/standard-headers/linux/virtio_config.h |  2 ++
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 006d3d1..9a6bfe7 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -39,6 +39,14 @@ typedef struct VRingDesc
     uint16_t next;
 } VRingDesc;
 
+typedef struct VRingDescPacked
+{
+    uint64_t addr;
+    uint32_t len;
+    uint16_t id;
+    uint16_t flags;
+} VRingDescPacked;
+
 typedef struct VRingAvail
 {
     uint16_t flags;
@@ -61,9 +69,18 @@ typedef struct VRingUsed
 
 typedef struct VRingMemoryRegionCaches {
     struct rcu_head rcu;
-    MemoryRegionCache desc;
-    MemoryRegionCache avail;
-    MemoryRegionCache used;
+    union {
+        struct {
+            MemoryRegionCache desc;
+            MemoryRegionCache avail;
+            MemoryRegionCache used;
+        };
+        struct {
+            MemoryRegionCache desc_packed;
+            MemoryRegionCache driver;
+            MemoryRegionCache device;
+        };
+    };
 } VRingMemoryRegionCaches;
 
 typedef struct VRing
@@ -77,10 +94,31 @@ typedef struct VRing
     VRingMemoryRegionCaches *caches;
 } VRing;
 
+typedef struct VRingPackedDescEvent {
+    uint16_t desc_event_off:15,
+             desc_event_wrap:1;
+    uint16_t desc_event_flags:2;
+} VRingPackedDescEvent ;
+
+typedef struct VRingPacked
+{
+    unsigned int num;
+    unsigned int num_default;
+    unsigned int align;
+    hwaddr desc;
+    hwaddr driver;
+    hwaddr device;
+    VRingMemoryRegionCaches *caches;
+} VRingPacked;
+
 struct VirtQueue
 {
-    VRing vring;
+    union {
+        struct VRing vring;
+        struct VRingPacked packed;
+    };
 
+    uint8_t wrap_counter:1;
     /* Next head to pop */
     uint16_t last_avail_idx;
 
@@ -1220,6 +1258,7 @@ void virtio_reset(void *opaque)
         vdev->vq[i].vring.num = vdev->vq[i].vring.num_default;
         vdev->vq[i].inuse = 0;
         virtio_virtqueue_reset_region_cache(&vdev->vq[i]);
+        vdev->vq[i].wrap_counter = 1;
     }
 }
 
diff --git a/include/hw/virtio/virtio.h b/include/hw/virtio/virtio.h
index 098bdaa..563e88e 100644
--- a/include/hw/virtio/virtio.h
+++ b/include/hw/virtio/virtio.h
@@ -46,6 +46,14 @@ typedef struct VirtQueueElement
     unsigned int index;
     unsigned int out_num;
     unsigned int in_num;
+
+    /* Number of descriptors used by packed ring */
+    uint16_t count;
+    uint8_t wrap_counter:1;
+    /* FIXME: Length of every used buffer for a descriptor,
+       move to dynamical allocating due to out/in sgs numbers */
+    uint32_t len[VIRTQUEUE_MAX_SIZE];
+
     hwaddr *in_addr;
     hwaddr *out_addr;
     struct iovec *in_sg;
@@ -262,7 +270,9 @@ typedef struct VirtIORNGConf VirtIORNGConf;
     DEFINE_PROP_BIT64("any_layout", _state, _field, \
                       VIRTIO_F_ANY_LAYOUT, true), \
     DEFINE_PROP_BIT64("iommu_platform", _state, _field, \
-                      VIRTIO_F_IOMMU_PLATFORM, false)
+                      VIRTIO_F_IOMMU_PLATFORM, false), \
+    DEFINE_PROP_BIT64("ring_packed", _state, _field, \
+                      VIRTIO_F_RING_PACKED, true)
 
 hwaddr virtio_queue_get_desc_addr(VirtIODevice *vdev, int n);
 hwaddr virtio_queue_get_avail_addr(VirtIODevice *vdev, int n);
diff --git a/include/standard-headers/linux/virtio_config.h b/include/standard-headers/linux/virtio_config.h
index b777069..6ee5529 100644
--- a/include/standard-headers/linux/virtio_config.h
+++ b/include/standard-headers/linux/virtio_config.h
@@ -71,4 +71,6 @@
  * this is for compatibility with legacy systems.
  */
 #define VIRTIO_F_IOMMU_PLATFORM		33
+
+#define VIRTIO_F_RING_PACKED		34
 #endif /* _LINUX_VIRTIO_CONFIG_H */
-- 
2.7.4