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[Qemu-devel] [PATCH v2 06/15] virtio: init and desc empty check for pack
From: |
wexu |
Subject: |
[Qemu-devel] [PATCH v2 06/15] virtio: init and desc empty check for packed ring |
Date: |
Wed, 16 Jan 2019 13:31:11 -0500 |
From: Wei Xu <address@hidden>
ring check and other basical helpers for packed ring.
Signed-off-by: Wei Xu <address@hidden>
---
hw/virtio/virtio.c | 59 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 58 insertions(+), 1 deletion(-)
diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 833289e..e728201 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -24,6 +24,9 @@
#include "hw/virtio/virtio-access.h"
#include "sysemu/dma.h"
+#define AVAIL_DESC_PACKED(b) ((b) << 7)
+#define USED_DESC_PACKED(b) ((b) << 15)
+
/*
* The alignment to use between consumer and producer parts of vring.
* x86 pagesize again. This is the default, used by transports like PCI
@@ -369,6 +372,25 @@ int virtio_queue_ready(VirtQueue *vq)
return vq->vring.avail != 0;
}
+static void vring_packed_desc_read_flags(VirtIODevice *vdev,
+ VRingPackedDesc *desc, MemoryRegionCache *cache, int i)
+{
+ address_space_read_cached(cache,
+ i * sizeof(VRingPackedDesc) + offsetof(VRingPackedDesc, flags),
+ &desc->flags, sizeof(desc->flags));
+ virtio_tswap16s(vdev, &desc->flags);
+}
+
+static inline bool is_desc_avail(struct VRingPackedDesc *desc,
+ bool wrap_counter)
+{
+ bool avail, used;
+
+ avail = !!(desc->flags & AVAIL_DESC_PACKED(1));
+ used = !!(desc->flags & USED_DESC_PACKED(1));
+ return (avail != used) && (avail == wrap_counter);
+}
+
/* Fetch avail_idx from VQ memory only when we really need to know if
* guest has added some buffers.
* Called within rcu_read_lock(). */
@@ -389,7 +411,7 @@ static int virtio_queue_empty_rcu(VirtQueue *vq)
return vring_avail_idx(vq) == vq->last_avail_idx;
}
-int virtio_queue_empty(VirtQueue *vq)
+static int virtio_queue_split_empty(VirtQueue *vq)
{
bool empty;
@@ -411,6 +433,41 @@ int virtio_queue_empty(VirtQueue *vq)
return empty;
}
+static int virtio_queue_packed_empty_rcu(VirtQueue *vq)
+{
+ struct VRingPackedDesc desc;
+ VRingMemoryRegionCaches *cache;
+
+ if (unlikely(!vq->vring.desc)) {
+ return 1;
+ }
+
+ cache = vring_get_region_caches(vq);
+ vring_packed_desc_read_flags(vq->vdev, &desc, &cache->desc,
+ vq->last_avail_idx);
+
+ return !is_desc_avail(&desc, vq->avail_wrap_counter);
+}
+
+static int virtio_queue_packed_empty(VirtQueue *vq)
+{
+ bool empty;
+
+ rcu_read_lock();
+ empty = virtio_queue_packed_empty_rcu(vq);
+ rcu_read_unlock();
+ return empty;
+}
+
+int virtio_queue_empty(VirtQueue *vq)
+{
+ if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) {
+ return virtio_queue_packed_empty(vq);
+ } else {
+ return virtio_queue_split_empty(vq);
+ }
+}
+
static void virtqueue_unmap_sg(VirtQueue *vq, const VirtQueueElement *elem,
unsigned int len)
{
--
1.8.3.1
- [Qemu-devel] [PATCH v2 00/15] packed ring virtio-net backends support, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 01/15] virtio: introduce packed ring definitions, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 02/15] virtio: redefine structure & memory cache for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 03/15] virtio: expand offset calculation for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 05/15] virtio: init wrap counter for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 04/15] virtio: add memory region init for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 06/15] virtio: init and desc empty check for packed ring,
wexu <=
- [Qemu-devel] [PATCH v2 08/15] virtio: fill/flush/pop for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 10/15] virtio-net: fill head desc after done all in a chain, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 12/15] virtio: add vhost-net migration for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 07/15] virtio: get avail bytes check for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 13/15] virtio: packed ring feature bit for userspace backend, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 09/15] virtio: event suppression support for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 11/15] virtio: add userspace migration for packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 14/15] vhost: enable packed ring, wexu, 2019/01/16
- [Qemu-devel] [PATCH v2 15/15] virtio: enable packed ring via a new command line, wexu, 2019/01/16