From nobody Fri Nov 7 10:15:07 2025 Delivered-To: importer@patchew.org Received-SPF: pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Authentication-Results: mx.zohomail.com; spf=pass (zoho.com: domain of gnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom=qemu-devel-bounces+importer=patchew.org@nongnu.org; dmarc=fail(p=none dis=none) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) by mx.zohomail.com with SMTPS id 1547664114724874.912345294277; Wed, 16 Jan 2019 10:41:54 -0800 (PST) Received: from localhost ([127.0.0.1]:45908 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gjq8P-0001qv-BF for importer@patchew.org; Wed, 16 Jan 2019 13:41:53 -0500 Received: from eggs.gnu.org ([209.51.188.92]:46896) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gjpyt-0003Bt-6i for qemu-devel@nongnu.org; Wed, 16 Jan 2019 13:32:04 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gjpyq-0007Tb-Rf for qemu-devel@nongnu.org; Wed, 16 Jan 2019 13:32:02 -0500 Received: from mx1.redhat.com ([209.132.183.28]:2308) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1gjpyq-0007ST-JG for qemu-devel@nongnu.org; Wed, 16 Jan 2019 13:32:00 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id C888EC075D7B; Wed, 16 Jan 2019 18:31:59 +0000 (UTC) Received: from dell-per430-12.lab.eng.pek2.redhat.com (dell-per430-12.lab.eng.pek2.redhat.com [10.73.196.55]) by smtp.corp.redhat.com (Postfix) with ESMTP id 394895C1B4; Wed, 16 Jan 2019 18:31:56 +0000 (UTC) From: wexu@redhat.com To: wexu@redhat.com, tiwei.bie@intel.com, qemu-devel@nongnu.org Date: Wed, 16 Jan 2019 13:31:11 -0500 Message-Id: <1547663480-547-7-git-send-email-wexu@redhat.com> In-Reply-To: <1547663480-547-1-git-send-email-wexu@redhat.com> References: <1547663480-547-1-git-send-email-wexu@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Wed, 16 Jan 2019 18:31:59 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: [Qemu-devel] [PATCH v2 06/15] virtio: init and desc empty check for packed ring X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jasowang@redhat.com, maxime.coquelin@redhat.com, jfreiman@redhat.com, mst@redhat.com Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" 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 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" =20 +#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 !=3D 0; } =20 +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, flag= s), + &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 =3D !!(desc->flags & AVAIL_DESC_PACKED(1)); + used =3D !!(desc->flags & USED_DESC_PACKED(1)); + return (avail !=3D used) && (avail =3D=3D 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) =3D=3D vq->last_avail_idx; } =20 -int virtio_queue_empty(VirtQueue *vq) +static int virtio_queue_split_empty(VirtQueue *vq) { bool empty; =20 @@ -411,6 +433,41 @@ int virtio_queue_empty(VirtQueue *vq) return empty; } =20 +static int virtio_queue_packed_empty_rcu(VirtQueue *vq) +{ + struct VRingPackedDesc desc; + VRingMemoryRegionCaches *cache; + + if (unlikely(!vq->vring.desc)) { + return 1; + } + + cache =3D 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 =3D 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) { --=20 1.8.3.1