From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 09FBCC74A4B for ; Thu, 11 Jul 2019 08:31:14 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id D1BFA21019 for ; Thu, 11 Jul 2019 08:31:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D1BFA21019 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39432 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hlUTw-0000K6-Bl for qemu-devel@archiver.kernel.org; Thu, 11 Jul 2019 04:31:12 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:56830) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hlUTL-0008Io-0o for qemu-devel@nongnu.org; Thu, 11 Jul 2019 04:30:36 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hlUTJ-0007rS-Iz for qemu-devel@nongnu.org; Thu, 11 Jul 2019 04:30:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:48672) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hlUTJ-0007p4-7h for qemu-devel@nongnu.org; Thu, 11 Jul 2019 04:30:33 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id AEAC6C057E9F; Thu, 11 Jul 2019 08:30:31 +0000 (UTC) Received: from work-vm (ovpn-117-165.ams2.redhat.com [10.36.117.165]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 82FEE1001DCC; Thu, 11 Jul 2019 08:30:23 +0000 (UTC) Date: Thu, 11 Jul 2019 09:30:20 +0100 From: "Dr. David Alan Gilbert" To: Wolfgang Bumiller Message-ID: <20190711083020.GB3971@work-vm> References: <20190710141440.27635-1-stefanha@redhat.com> <20190711071843.GA9211@olga.proxmox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190711071843.GA9211@olga.proxmox.com> User-Agent: Mutt/1.12.0 (2019-05-25) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 11 Jul 2019 08:30:32 +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: Re: [Qemu-devel] [PATCH] virtio-balloon: fix QEMU 4.0 config size migration incompatibility X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Eduardo Habkost , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Stefan Hajnoczi Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Wolfgang Bumiller (w.bumiller@proxmox.com) wrote: > On Wed, Jul 10, 2019 at 04:14:40PM +0200, Stefan Hajnoczi wrote: > > The virtio-balloon config size changed in QEMU 4.0 even for existing > > machine types. Migration from QEMU 3.1 to 4.0 can fail in some > > circumstances with the following error: > > > > qemu-system-x86_64: get_pci_config_device: Bad config data: i=0x10 read: a1 device: 1 cmask: ff wmask: c0 w1cmask:0 > > > > This happens because the virtio-balloon config size affects the VIRTIO > > Legacy I/O Memory PCI BAR size. > > > > Introduce a qdev property called "qemu-4-0-config-size" and enable it > > only for the QEMU 4.0 machine types. This way <4.0 machine types use > > the old size, 4.0 uses the larger size, and >4.0 machine types use the > > appropriate size depending on enabled virtio-balloon features. > > > > Live migration to and from old QEMUs to QEMU 4.1 works again as long as > > a versioned machine type is specified (do not use just "pc"!). > > > > Originally-by: Wolfgang Bumiller > > Signed-off-by: Stefan Hajnoczi > > Tested-by: Wolfgang Bumiller > > Works with my otherwise failing VM from 3.0.1 -> patched-4.0. > Somehow I missed the `DEFINE_PROP_*` macros, sorry, and thanks for > fixing this up. Thanks again for spotting it! Dave > > --- > > include/hw/virtio/virtio-balloon.h | 2 ++ > > hw/core/machine.c | 2 ++ > > hw/virtio/virtio-balloon.c | 28 +++++++++++++++++++++++++--- > > 3 files changed, 29 insertions(+), 3 deletions(-) > > > > diff --git a/include/hw/virtio/virtio-balloon.h b/include/hw/virtio/virtio-balloon.h > > index 1afafb12f6..5a99293a45 100644 > > --- a/include/hw/virtio/virtio-balloon.h > > +++ b/include/hw/virtio/virtio-balloon.h > > @@ -71,6 +71,8 @@ typedef struct VirtIOBalloon { > > int64_t stats_poll_interval; > > uint32_t host_features; > > PartiallyBalloonedPage *pbp; > > + > > + bool qemu_4_0_config_size; > > } VirtIOBalloon; > > > > #endif > > diff --git a/hw/core/machine.c b/hw/core/machine.c > > index 2be19ec0cd..c4ead16010 100644 > > --- a/hw/core/machine.c > > +++ b/hw/core/machine.c > > @@ -34,6 +34,7 @@ GlobalProperty hw_compat_4_0[] = { > > { "virtio-vga", "edid", "false" }, > > { "virtio-gpu-pci", "edid", "false" }, > > { "virtio-device", "use-started", "false" }, > > + { "virtio-balloon-device", "qemu-4-0-config-size", "true" }, > > }; > > const size_t hw_compat_4_0_len = G_N_ELEMENTS(hw_compat_4_0); > > > > @@ -49,6 +50,7 @@ GlobalProperty hw_compat_3_1[] = { > > { "usb-tablet", "serial", "42" }, > > { "virtio-blk-device", "discard", "false" }, > > { "virtio-blk-device", "write-zeroes", "false" }, > > + { "virtio-balloon-device", "qemu-4-0-config-size", "false" }, > > }; > > const size_t hw_compat_3_1_len = G_N_ELEMENTS(hw_compat_3_1); > > > > diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c > > index 11fad86d64..e85d1c0d5c 100644 > > --- a/hw/virtio/virtio-balloon.c > > +++ b/hw/virtio/virtio-balloon.c > > @@ -615,6 +615,22 @@ virtio_balloon_free_page_report_notify(NotifierWithReturn *n, void *data) > > return 0; > > } > > > > +static size_t virtio_balloon_config_size(VirtIOBalloon *s) > > +{ > > + uint64_t features = s->host_features; > > + > > + if (s->qemu_4_0_config_size) { > > + return sizeof(struct virtio_balloon_config); > > + } > > + if (virtio_has_feature(features, VIRTIO_BALLOON_F_PAGE_POISON)) { > > + return sizeof(struct virtio_balloon_config); > > + } > > + if (virtio_has_feature(features, VIRTIO_BALLOON_F_FREE_PAGE_HINT)) { > > + return offsetof(struct virtio_balloon_config, poison_val); > > + } > > + return offsetof(struct virtio_balloon_config, free_page_report_cmd_id); > > +} > > + > > static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data) > > { > > VirtIOBalloon *dev = VIRTIO_BALLOON(vdev); > > @@ -635,7 +651,7 @@ static void virtio_balloon_get_config(VirtIODevice *vdev, uint8_t *config_data) > > } > > > > trace_virtio_balloon_get_config(config.num_pages, config.actual); > > - memcpy(config_data, &config, sizeof(struct virtio_balloon_config)); > > + memcpy(config_data, &config, virtio_balloon_config_size(dev)); > > } > > > > static int build_dimm_list(Object *obj, void *opaque) > > @@ -679,7 +695,7 @@ static void virtio_balloon_set_config(VirtIODevice *vdev, > > uint32_t oldactual = dev->actual; > > ram_addr_t vm_ram_size = get_current_ram_size(); > > > > - memcpy(&config, config_data, sizeof(struct virtio_balloon_config)); > > + memcpy(&config, config_data, virtio_balloon_config_size(dev)); > > dev->actual = le32_to_cpu(config.actual); > > if (dev->actual != oldactual) { > > qapi_event_send_balloon_change(vm_ram_size - > > @@ -766,7 +782,7 @@ static void virtio_balloon_device_realize(DeviceState *dev, Error **errp) > > int ret; > > > > virtio_init(vdev, "virtio-balloon", VIRTIO_ID_BALLOON, > > - sizeof(struct virtio_balloon_config)); > > + virtio_balloon_config_size(s)); > > > > ret = qemu_add_balloon_handler(virtio_balloon_to_target, > > virtio_balloon_stat, s); > > @@ -897,6 +913,12 @@ static Property virtio_balloon_properties[] = { > > VIRTIO_BALLOON_F_DEFLATE_ON_OOM, false), > > DEFINE_PROP_BIT("free-page-hint", VirtIOBalloon, host_features, > > VIRTIO_BALLOON_F_FREE_PAGE_HINT, false), > > + /* QEMU 4.0 accidentally changed the config size even when free-page-hint > > + * is disabled, resulting in QEMU 3.1 migration incompatibility. This > > + * property retains this quirk for QEMU 4.1 machine types. > > + */ > > + DEFINE_PROP_BOOL("qemu-4-0-config-size", VirtIOBalloon, > > + qemu_4_0_config_size, false), > > DEFINE_PROP_LINK("iothread", VirtIOBalloon, iothread, TYPE_IOTHREAD, > > IOThread *), > > DEFINE_PROP_END_OF_LIST(), > > -- > > 2.21.0 > > > > > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK