From patchwork Thu Oct 11 14:08:31 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wei Xu X-Patchwork-Id: 10636687 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B46C313AD for ; Thu, 11 Oct 2018 14:16:52 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A63602B7EB for ; Thu, 11 Oct 2018 14:16:52 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 980962B7F8; Thu, 11 Oct 2018 14:16:52 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 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 mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 19BC72B7EB for ; 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Thu, 11 Oct 2018 14:09:20 +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 26B7E5D6A9; Thu, 11 Oct 2018 14:09:17 +0000 (UTC) From: wexu@redhat.com To: qemu-devel@nongnu.org Date: Thu, 11 Oct 2018 10:08:31 -0400 Message-Id: <1539266915-15216-9-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> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.43]); Thu, 11 Oct 2018 14:09:20 +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] [[RFC v3 08/12] virtio: event suppression support 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: maxime.coquelin@redhat.com, jasowang@redhat.com, jfreimann@redhat.com, wexu@redhat.com, tiwei.bie@intel.com Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" X-Virus-Scanned: ClamAV using ClamSMTP From: Wei Xu Signed-off-by: Wei Xu --- hw/virtio/virtio.c | 126 +++++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 123 insertions(+), 3 deletions(-) diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c index d12a7e3..1d25776 100644 --- a/hw/virtio/virtio.c +++ b/hw/virtio/virtio.c @@ -241,6 +241,30 @@ static void vring_desc_read(VirtIODevice *vdev, VRingDesc *desc, virtio_tswap16s(vdev, &desc->next); } +static void vring_packed_event_read(VirtIODevice *vdev, + MemoryRegionCache *cache, VRingPackedDescEvent *e) +{ + address_space_read_cached(cache, 0, e, sizeof(*e)); + virtio_tswap16s(vdev, &e->off_wrap); + virtio_tswap16s(vdev, &e->flags); +} + +static void vring_packed_off_wrap_write(VirtIODevice *vdev, + MemoryRegionCache *cache, uint16_t off_wrap) +{ + virtio_tswap16s(vdev, &off_wrap); + address_space_write_cached(cache, 0, &off_wrap, sizeof(off_wrap)); + address_space_cache_invalidate(cache, 0, sizeof(off_wrap)); +} + +static void vring_packed_flags_write(VirtIODevice *vdev, + MemoryRegionCache *cache, uint16_t flags) +{ + virtio_tswap16s(vdev, &flags); + address_space_write_cached(cache, sizeof(uint16_t), &flags, sizeof(flags)); + address_space_cache_invalidate(cache, sizeof(uint16_t), sizeof(flags)); +} + static VRingMemoryRegionCaches *vring_get_region_caches(struct VirtQueue *vq) { VRingMemoryRegionCaches *caches = atomic_rcu_read(&vq->vring.caches); @@ -347,7 +371,7 @@ static inline void vring_set_avail_event(VirtQueue *vq, uint16_t val) address_space_cache_invalidate(&caches->used, pa, sizeof(val)); } -void virtio_queue_set_notification(VirtQueue *vq, int enable) +static void virtio_queue_set_notification_split(VirtQueue *vq, int enable) { vq->notification = enable; @@ -370,6 +394,51 @@ void virtio_queue_set_notification(VirtQueue *vq, int enable) rcu_read_unlock(); } +static void virtio_queue_set_notification_packed(VirtQueue *vq, int enable) +{ + VRingPackedDescEvent e; + VRingMemoryRegionCaches *caches; + + rcu_read_lock(); + caches = vring_get_region_caches(vq); + vring_packed_event_read(vq->vdev, &caches->device, &e); + + if (!enable) { + e.flags = RING_EVENT_FLAGS_DISABLE; + goto out; + } + + e.flags = RING_EVENT_FLAGS_ENABLE; + if (virtio_vdev_has_feature(vq->vdev, VIRTIO_RING_F_EVENT_IDX)) { + uint16_t off_wrap = vq->event_idx | vq->event_wrap_counter << 15; + + vring_packed_off_wrap_write(vq->vdev, &caches->device, off_wrap); + /* Make sure off_wrap is wrote before flags */ + smp_wmb(); + + e.flags = RING_EVENT_FLAGS_DESC; + } + +out: + vring_packed_flags_write(vq->vdev, &caches->device, e.flags); + rcu_read_unlock(); +} + +void virtio_queue_set_notification(VirtQueue *vq, int enable) +{ + vq->notification = enable; + + if (!vq->vring.desc) { + return; + } + + if (virtio_vdev_has_feature(vq->vdev, VIRTIO_F_RING_PACKED)) { + virtio_queue_set_notification_packed(vq, enable); + } else { + virtio_queue_set_notification_split(vq, enable); + } +} + int virtio_queue_ready(VirtQueue *vq) { return vq->vring.avail != 0; @@ -2103,8 +2172,7 @@ static void virtio_set_isr(VirtIODevice *vdev, int value) } } -/* Called within rcu_read_lock(). */ -static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq) +static bool virtio_split_should_notify(VirtIODevice *vdev, VirtQueue *vq) { uint16_t old, new; bool v; @@ -2127,6 +2195,58 @@ static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq) return !v || vring_need_event(vring_get_used_event(vq), new, old); } +static bool vring_packed_need_event(VirtQueue *vq, uint16_t off_wrap, + uint16_t new, uint16_t old) +{ + bool wrap = vq->event_wrap_counter; + int off = off_wrap & ~(1 << 15); + + if (new < old) { + new += vq->vring.num; + wrap ^= 1; + } + + if (wrap != off_wrap >> 15) { + off += vq->vring.num; + } + + return vring_need_event(off, new, old); +} + +static bool virtio_packed_should_notify(VirtIODevice *vdev, VirtQueue *vq) +{ + VRingPackedDescEvent e; + uint16_t old, new; + bool v; + VRingMemoryRegionCaches *caches; + + caches = vring_get_region_caches(vq); + vring_packed_event_read(vdev, &caches->driver, &e); + + old = vq->signalled_used; + new = vq->signalled_used = vq->used_idx; + v = vq->signalled_used_valid; + vq->signalled_used_valid = true; + + if (e.flags == RING_EVENT_FLAGS_DISABLE) { + return false; + } else if (e.flags == RING_EVENT_FLAGS_ENABLE) { + return true; + } + + return !v || vring_packed_need_event(vq, e.off_wrap, new, old); +} + +/* Called within rcu_read_lock(). */ +static bool virtio_should_notify(VirtIODevice *vdev, VirtQueue *vq) +{ + if (virtio_vdev_has_feature(vdev, VIRTIO_F_RING_PACKED)) { + return virtio_packed_should_notify(vdev, vq); + } else { + return virtio_split_should_notify(vdev, vq); + } +} + void virtio_notify_irqfd(VirtIODevice *vdev, VirtQueue *vq) { bool should_notify;