From patchwork Tue Jun 5 19:07:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Xu X-Patchwork-Id: 925608 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=208.118.235.17; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=redhat.com Received: from lists.gnu.org (lists.gnu.org [208.118.235.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 410hLT710Jz9s0W for ; Wed, 6 Jun 2018 05:14:09 +1000 (AEST) Received: from localhost ([::1]:48679 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fQHPD-0007EO-L7 for incoming@patchwork.ozlabs.org; Tue, 05 Jun 2018 15:14:07 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42561) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fQHJf-00023h-Fk for qemu-devel@nongnu.org; Tue, 05 Jun 2018 15:08:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fQHJc-00032g-Hw for qemu-devel@nongnu.org; Tue, 05 Jun 2018 15:08:23 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:46868 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fQHJc-00032C-BM for qemu-devel@nongnu.org; Tue, 05 Jun 2018 15:08:20 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DA608125933; Tue, 5 Jun 2018 19:08:19 +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 522C62026DEF; Tue, 5 Jun 2018 19:08:17 +0000 (UTC) From: wexu@redhat.com To: qemu-devel@nongnu.org Date: Tue, 5 Jun 2018 15:07:58 -0400 Message-Id: <1528225683-11413-4-git-send-email-wexu@redhat.com> In-Reply-To: <1528225683-11413-1-git-send-email-wexu@redhat.com> References: <1528225683-11413-1-git-send-email-wexu@redhat.com> X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Tue, 05 Jun 2018 19:08:19 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.1]); Tue, 05 Jun 2018 19:08:19 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'wexu@redhat.com' RCPT:'' X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 66.187.233.73 Subject: [Qemu-devel] [RFC v2 3/8] virtio: empty check and desc read 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, jfreimann@redhat.com, wexu@redhat.com, tiwei.bie@intel.com, mst@redhat.com Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" From: Wei Xu helper for ring empty check and descriptor read. Signed-off-by: Wei Xu --- hw/virtio/virtio.c | 62 +++++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 59 insertions(+), 3 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index f6c0689..bd669a2 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 @@ -357,10 +360,27 @@ int virtio_queue_ready(VirtQueue *vq) return vq->vring.avail != 0; } +static void vring_packed_desc_read(VirtIODevice *vdev, VRingDescPacked *desc, + MemoryRegionCache *cache, int i) +{ + address_space_read_cached(cache, i * sizeof(VRingDescPacked), + desc, sizeof(VRingDescPacked)); + virtio_tswap64s(vdev, &desc->addr); + virtio_tswap32s(vdev, &desc->len); + virtio_tswap16s(vdev, &desc->id); + virtio_tswap16s(vdev, &desc->flags); +} + +static inline bool is_desc_avail(struct VRingDescPacked *desc) +{ + return !!(desc->flags & AVAIL_DESC_PACKED(1)) != + !!(desc->flags & USED_DESC_PACKED(1)); +} + /* Fetch avail_idx from VQ memory only when we really need to know if * guest has added some buffers. * Called within rcu_read_lock(). */ -static int virtio_queue_empty_rcu(VirtQueue *vq) +static int virtio_queue_split_empty_rcu(VirtQueue *vq) { if (unlikely(!vq->vring.avail)) { return 1; @@ -373,7 +393,7 @@ 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; @@ -391,6 +411,42 @@ int virtio_queue_empty(VirtQueue *vq) return empty; } +static int virtio_queue_packed_empty_rcu(VirtQueue *vq) +{ + struct VRingDescPacked desc; + VRingMemoryRegionCaches *cache; + + if (unlikely(!vq->vring.desc)) { + return 1; + } + + cache = vring_get_region_caches(vq); + vring_packed_desc_read(vq->vdev, &desc, &cache->desc, vq->last_avail_idx); + + /* Make sure we see the updated flag */ + smp_mb(); + return !is_desc_avail(&desc); +} + +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) { @@ -862,7 +918,7 @@ void *virtqueue_pop(VirtQueue *vq, size_t sz) return NULL; } rcu_read_lock(); - if (virtio_queue_empty_rcu(vq)) { + if (virtio_queue_split_empty_rcu(vq)) { goto done; } /* Needed after virtio_queue_empty(), see comment in