From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35967) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gPpez-0005JD-95 for qemu-devel@nongnu.org; Thu, 22 Nov 2018 09:08:50 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gPpev-0001Pq-CQ for qemu-devel@nongnu.org; Thu, 22 Nov 2018 09:08:49 -0500 Received: from mx1.redhat.com ([209.132.183.28]:57584) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gPpev-0001O5-59 for qemu-devel@nongnu.org; Thu, 22 Nov 2018 09:08:45 -0500 From: wexu@redhat.com Date: Thu, 22 Nov 2018 09:06:12 -0500 Message-Id: <1542895581-10721-8-git-send-email-wexu@redhat.com> In-Reply-To: <1542895581-10721-1-git-send-email-wexu@redhat.com> References: <1542895581-10721-1-git-send-email-wexu@redhat.com> Subject: [Qemu-devel] [PATCH v1 07/16] virtio: init and desc empty check for packed ring List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: jasowang@redhat.com, qemu-devel@nongnu.org Cc: mst@redhat.com, wexu@redhat.com, jfreimann@redhat.com, maxime.coquelin@redhat.com, tiwei.bie@intel.com From: Wei Xu ring check and other basical helpers for packed ring. Signed-off-by: Wei Xu --- 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 74d9710..9d485e4 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