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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, 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 C0FD6C74A4B for ; Thu, 11 Jul 2019 07:28:47 +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 9972720838 for ; Thu, 11 Jul 2019 07:28:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9972720838 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=proxmox.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39140 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hlTVW-0000su-3e for qemu-devel@archiver.kernel.org; Thu, 11 Jul 2019 03:28:46 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:35596) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hlTV1-0000OY-Ss for qemu-devel@nongnu.org; Thu, 11 Jul 2019 03:28:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hlTV0-0005ix-K0 for qemu-devel@nongnu.org; Thu, 11 Jul 2019 03:28:15 -0400 Received: from proxmox-new.maurer-it.com ([212.186.127.180]:50506) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hlTV0-0005fu-8D for qemu-devel@nongnu.org; Thu, 11 Jul 2019 03:28:14 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 6747445463; Thu, 11 Jul 2019 09:18:45 +0200 (CEST) Date: Thu, 11 Jul 2019 09:18:43 +0200 From: Wolfgang Bumiller To: Stefan Hajnoczi Message-ID: <20190711071843.GA9211@olga.proxmox.com> References: <20190710141440.27635-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190710141440.27635-1-stefanha@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 212.186.127.180 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: "Dr. David Alan Gilbert" , "Michael S. Tsirkin" , qemu-devel@nongnu.org, Eduardo Habkost Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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. > --- > 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 > >