From patchwork Sun Jan 10 14:21:07 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Michael S. Tsirkin" X-Patchwork-Id: 7996501 Return-Path: X-Original-To: patchwork-linux-sh@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 1BD6C9F1C0 for ; Sun, 10 Jan 2016 14:23:56 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 4E8882024D for ; Sun, 10 Jan 2016 14:23:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE6B420259 for ; Sun, 10 Jan 2016 14:23:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757889AbcAJOVU (ORCPT ); Sun, 10 Jan 2016 09:21:20 -0500 Received: from mx1.redhat.com ([209.132.183.28]:54288 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757300AbcAJOVP (ORCPT ); Sun, 10 Jan 2016 09:21:15 -0500 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (Postfix) with ESMTPS id 56BC07D; Sun, 10 Jan 2016 14:21:15 +0000 (UTC) Received: from redhat.com (vpn1-5-155.ams2.redhat.com [10.36.5.155]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with SMTP id u0AEL8YI019556; Sun, 10 Jan 2016 09:21:08 -0500 Date: Sun, 10 Jan 2016 16:21:07 +0200 From: "Michael S. Tsirkin" To: linux-kernel@vger.kernel.org Cc: Peter Zijlstra , Arnd Bergmann , linux-arch@vger.kernel.org, Andrew Cooper , Russell King - ARM Linux , virtualization@lists.linux-foundation.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Joe Perches , David Miller , linux-ia64@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, sparclinux@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-metag@vger.kernel.org, linux-mips@linux-mips.org, x86@kernel.org, user-mode-linux-devel@lists.sourceforge.net, adi-buildroot-devel@lists.sourceforge.net, linux-sh@vger.kernel.org, linux-xtensa@linux-xtensa.org, xen-devel@lists.xenproject.org Subject: [PATCH v3 33/41] virtio_ring: use virt_store_mb Message-ID: <1452426622-4471-34-git-send-email-mst@redhat.com> References: <1452426622-4471-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1452426622-4471-1-git-send-email-mst@redhat.com> X-Mutt-Fcc: =sent X-Scanned-By: MIMEDefang 2.68 on 10.5.11.23 Sender: linux-sh-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP We need a full barrier after writing out event index, using virt_store_mb there seems better than open-coding. As usual, we need a wrapper to account for strong barriers. It's tempting to use this in vhost as well, for that, we'll need a variant of smp_store_mb that works on __user pointers. Signed-off-by: Michael S. Tsirkin --- include/linux/virtio_ring.h | 11 +++++++++++ drivers/virtio/virtio_ring.c | 15 +++++++++------ 2 files changed, 20 insertions(+), 6 deletions(-) diff --git a/include/linux/virtio_ring.h b/include/linux/virtio_ring.h index f3fa55b..a156e2b 100644 --- a/include/linux/virtio_ring.h +++ b/include/linux/virtio_ring.h @@ -45,6 +45,17 @@ static inline void virtio_wmb(bool weak_barriers) wmb(); } +static inline void virtio_store_mb(bool weak_barriers, + __virtio16 *p, __virtio16 v) +{ + if (weak_barriers) { + virt_store_mb(*p, v); + } else { + WRITE_ONCE(*p, v); + mb(); + } +} + struct virtio_device; struct virtqueue; diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index ee663c4..e12e385 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -517,10 +517,10 @@ void *virtqueue_get_buf(struct virtqueue *_vq, unsigned int *len) /* If we expect an interrupt for the next entry, tell host * by writing event index and flush out the write before * the read in the next get_buf call. */ - if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) { - vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, vq->last_used_idx); - virtio_mb(vq->weak_barriers); - } + if (!(vq->avail_flags_shadow & VRING_AVAIL_F_NO_INTERRUPT)) + virtio_store_mb(vq->weak_barriers, + &vring_used_event(&vq->vring), + cpu_to_virtio16(_vq->vdev, vq->last_used_idx)); #ifdef DEBUG vq->last_add_time_valid = false; @@ -653,8 +653,11 @@ bool virtqueue_enable_cb_delayed(struct virtqueue *_vq) } /* TODO: tune this threshold */ bufs = (u16)(vq->avail_idx_shadow - vq->last_used_idx) * 3 / 4; - vring_used_event(&vq->vring) = cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs); - virtio_mb(vq->weak_barriers); + + virtio_store_mb(vq->weak_barriers, + &vring_used_event(&vq->vring), + cpu_to_virtio16(_vq->vdev, vq->last_used_idx + bufs)); + if (unlikely((u16)(virtio16_to_cpu(_vq->vdev, vq->vring.used->idx) - vq->last_used_idx) > bufs)) { END_USE(vq); return false;