From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=39777 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PRjAY-0008G6-Ny for qemu-devel@nongnu.org; Sun, 12 Dec 2010 05:28:43 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PRjAX-0007w6-Dq for qemu-devel@nongnu.org; Sun, 12 Dec 2010 05:28:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47592) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PRjAX-0007vy-3T for qemu-devel@nongnu.org; Sun, 12 Dec 2010 05:28:41 -0500 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id oBCASZPi031764 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 12 Dec 2010 05:28:35 -0500 Date: Sun, 12 Dec 2010 12:28:12 +0200 From: "Michael S. Tsirkin" Message-ID: <20101212102812.GA13033@redhat.com> References: <20101209191623.15450.19696.stgit@s20.home> <1291932857.2926.20.camel@x201> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1291932857.2926.20.camel@x201> Subject: [Qemu-devel] Re: [PATCH] rtl8139: IO memory is not part of vmstate List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: qemu-devel@nongnu.org, quintela@redhat.com On Thu, Dec 09, 2010 at 03:14:17PM -0700, Alex Williamson wrote: > On Thu, 2010-12-09 at 22:49 +0100, Juan Quintela wrote: > > Alex Williamson wrote: > > > The cpu_register_io_memory() value is unique to the VM instance and > > > should not be restored after migration/save. Doing so means we > > > could be pointing at arbitrary device's io regions after migration/restore. > > > > > > In this case, if we start a VM with a single rtl8139, hot add a 2nd, > > > migrate the VM, then hot remove the added NIC, the 1st NIC stops > > > working and the VM segfaults on reboot. > > > > > > Signed-off-by: Alex Williamson > > > --- > > > > > > hw/rtl8139.c | 4 ++-- > > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > > > diff --git a/hw/rtl8139.c b/hw/rtl8139.c > > > index d92981d..9c5fc84 100644 > > > --- a/hw/rtl8139.c > > > +++ b/hw/rtl8139.c > > > @@ -3186,7 +3186,7 @@ static void rtl8139_pre_save(void *opaque) > > > > > > static const VMStateDescription vmstate_rtl8139 = { > > > .name = "rtl8139", > > > - .version_id = 4, > > > + .version_id = 5, > > > > No need to change version, format is still the same. > > > > > .minimum_version_id = 3, > > > .minimum_version_id_old = 3, > > > .post_load = rtl8139_post_load, > > > @@ -3234,7 +3234,7 @@ static const VMStateDescription vmstate_rtl8139 = { > > > > > > VMSTATE_UNUSED(4), > > > VMSTATE_MACADDR(conf.macaddr, RTL8139State), > > > - VMSTATE_INT32(rtl8139_mmio_io_addr, RTL8139State), > > > + VMSTATE_UNUSED(4), > > > > If we migrate from an old guest: we just ignore the value. > > If we migrate to one old guest, we send garbage, but as you told that we > > were already sending garbage, it looks ok, no? > > NAK, if we don't bump the version, we don't know if we're migration > to/from a version 4 that includes the io address or not. We have no > good way to debug different binaries on different systems. It seems to > work today if we don't involve hotplug, so I think we have to maintain > version 4 as including the io address, and let version 5 drop it. I > tested old to new migrations, and as you expect, it does work. > > Alex How about we keep migrating the index for the benefit of old versions, but ignore the value on load? Something like the following: Signed-off-by: Michael S. Tsirkin diff --git a/hw/rtl8139.c b/hw/rtl8139.c index d92981d..e999dd9 100644 --- a/hw/rtl8139.c +++ b/hw/rtl8139.c @@ -494,6 +494,13 @@ typedef struct RTL8139State { QEMUTimer *timer; int64_t TimerExpire; + /* Hack for migration compatibility: older + * versions of rtl8139 put mmio index in save image, + * and override the index that we have with that one. + * This does not make any sense but happens to + * work sometimes, if we are lucky and index matches. + * On load, we can simply ignore this value. */ + int compat_rtl8139_mmio_io_addr; } RTL8139State; static void rtl8139_set_next_tctr_time(RTL8139State *s, int64_t current_time); @@ -3182,6 +3189,7 @@ static void rtl8139_pre_save(void *opaque) rtl8139_set_next_tctr_time(s, current_time); s->TCTR = muldiv64(current_time - s->TCTR_base, PCI_FREQUENCY, get_ticks_per_sec()); + s->compat_rtl8139_mmio_io_addr = s->rtl8139_mmio_io_addr; } static const VMStateDescription vmstate_rtl8139 = { @@ -3234,7 +3242,7 @@ static const VMStateDescription vmstate_rtl8139 = { VMSTATE_UNUSED(4), VMSTATE_MACADDR(conf.macaddr, RTL8139State), - VMSTATE_INT32(rtl8139_mmio_io_addr, RTL8139State), + VMSTATE_INT32(compat_rtl8139_mmio_io_addr, RTL8139State), VMSTATE_UINT32(currTxDesc, RTL8139State), VMSTATE_UINT32(currCPlusRxDesc, RTL8139State),