From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:39291) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gAbeP-0004p6-IX for qemu-devel@nongnu.org; Thu, 11 Oct 2018 10:09:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gAbeL-0005zI-PH for qemu-devel@nongnu.org; Thu, 11 Oct 2018 10:09:17 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65252) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gAbeL-0005xl-Ep for qemu-devel@nongnu.org; Thu, 11 Oct 2018 10:09:13 -0400 From: wexu@redhat.com Date: Thu, 11 Oct 2018 10:08:28 -0400 Message-Id: <1539266915-15216-6-git-send-email-wexu@redhat.com> In-Reply-To: <1539266915-15216-1-git-send-email-wexu@redhat.com> References: <1539266915-15216-1-git-send-email-wexu@redhat.com> Subject: [Qemu-devel] [[RFC v3 05/12] virtio: init and desc empty check for packed ring List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: jasowang@redhat.com, tiwei.bie@intel.com, wexu@redhat.com, jfreimann@redhat.com, maxime.coquelin@redhat.com From: Wei Xu Basic initialization and helpers for packed ring. Signed-off-by: Wei Xu --- hw/virtio/virtio.c | 57 +++++++++++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 56 insertions(+), 1 deletion(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index 9185efb..86f88da 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 @@ -372,6 +375,23 @@ 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)); +} + +static inline bool is_desc_avail(struct VRingPackedDesc *desc, bool wc) +{ + bool avail, used; + + avail = !!(desc->flags & AVAIL_DESC_PACKED(1)); + used = !!(desc->flags & USED_DESC_PACKED(1)); + return (avail != used) && (avail == wc); +} + /* Fetch avail_idx from VQ memory only when we really need to know if * guest has added some buffers. * Called within rcu_read_lock(). */ @@ -392,7 +412,7 @@ 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; @@ -414,6 +434,41 @@ 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