From patchwork Fri Aug 30 09:03:08 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Cornelia Huck X-Patchwork-Id: 271181 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 56DDB2C009C for ; Fri, 30 Aug 2013 19:04:17 +1000 (EST) Received: from localhost ([::1]:48206 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VFKcp-0005QG-9r for incoming@patchwork.ozlabs.org; Fri, 30 Aug 2013 05:04:15 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45814) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VFKc6-00058b-3o for qemu-devel@nongnu.org; Fri, 30 Aug 2013 05:03:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VFKbw-0004CO-F4 for qemu-devel@nongnu.org; Fri, 30 Aug 2013 05:03:30 -0400 Received: from e06smtp10.uk.ibm.com ([195.75.94.106]:53556) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VFKbw-0004BE-5R for qemu-devel@nongnu.org; Fri, 30 Aug 2013 05:03:20 -0400 Received: from /spool/local by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 30 Aug 2013 10:00:09 +0100 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp02.portsmouth.uk.ibm.com (Postfix) with ESMTP id 2A9592190061 for ; Fri, 30 Aug 2013 10:03:17 +0100 (BST) Received: from d06av10.portsmouth.uk.ibm.com (d06av10.portsmouth.uk.ibm.com [9.149.37.251]) by b06cxnps4076.portsmouth.uk.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r7U9350m57409668 for ; Fri, 30 Aug 2013 09:03:05 GMT Received: from d06av10.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av10.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r7U93GTx028659 for ; Fri, 30 Aug 2013 03:03:16 -0600 Received: from tuxmaker.boeblingen.de.ibm.com (tuxmaker.boeblingen.de.ibm.com [9.152.85.9]) by d06av10.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVin) with ESMTP id r7U93CLw028452; Fri, 30 Aug 2013 03:03:16 -0600 From: Cornelia Huck To: Alexander Graf Date: Fri, 30 Aug 2013 11:03:08 +0200 Message-Id: <1377853388-39470-2-git-send-email-cornelia.huck@de.ibm.com> X-Mailer: git-send-email 1.8.3.4 In-Reply-To: <1377853388-39470-1-git-send-email-cornelia.huck@de.ibm.com> References: <1377853388-39470-1-git-send-email-cornelia.huck@de.ibm.com> X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13083009-4966-0000-0000-000006BC6E20 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.4.x-2.6.x [generic] X-Received-From: 195.75.94.106 Cc: Cornelia Huck , Christian Borntraeger , qemu-devel , Dominik Dingel , Paolo Bonzini Subject: [Qemu-devel] [PATCH v2] s390-ccw: Fix waiting for virtio processing. X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org The guest side must not manipulate the index for the used buffers. Instead, remember the state of the used buffer locally and wait until it has moved. Signed-off-by: Cornelia Huck Acked-by: Alexander Graf --- v1 -> v2: Move setting the used index as by Paolo's suggestion --- pc-bios/s390-ccw/virtio.c | 7 ++++--- pc-bios/s390-ccw/virtio.h | 1 + 2 files changed, 5 insertions(+), 3 deletions(-) diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c index 49f2d29..4d6e48f 100644 --- a/pc-bios/s390-ccw/virtio.c +++ b/pc-bios/s390-ccw/virtio.c @@ -123,6 +123,7 @@ static void vring_init(struct vring *vr, unsigned int num, void *p, /* We're running with interrupts off anyways, so don't bother */ vr->used->flags = VRING_USED_F_NO_NOTIFY; vr->used->idx = 0; + vr->used_idx = 0; debug_print_addr("init vr", vr); } @@ -150,8 +151,6 @@ static void vring_send_buf(struct vring *vr, void *p, int len, int flags) if (!(flags & VRING_DESC_F_NEXT)) { vr->avail->idx++; } - - vr->used->idx = vr->next_idx; } static u64 get_clock(void) @@ -180,7 +179,8 @@ static int vring_wait_reply(struct vring *vr, int timeout) struct subchannel_id schid = vr->schid; int r = 0; - while (vr->used->idx == vr->next_idx) { + /* Wait until the used index has moved. */ + while (vr->used->idx == vr->used_idx) { vring_notify(schid); if (timeout && (get_second() >= target_second)) { r = 1; @@ -189,6 +189,7 @@ static int vring_wait_reply(struct vring *vr, int timeout) yield(); } + vr->used_idx = vr->used->idx; vr->next_idx = 0; vr->desc[0].len = 0; vr->desc[0].flags = 0; diff --git a/pc-bios/s390-ccw/virtio.h b/pc-bios/s390-ccw/virtio.h index 86fdd57..772a63f 100644 --- a/pc-bios/s390-ccw/virtio.h +++ b/pc-bios/s390-ccw/virtio.h @@ -115,6 +115,7 @@ struct vring_used { struct vring { unsigned int num; int next_idx; + int used_idx; struct vring_desc *desc; struct vring_avail *avail; struct vring_used *used;