Message ID | 1345107469-26996-1-git-send-email-stefanha@linux.vnet.ibm.com |
---|---|
State | New |
Headers | show |
Am 16.08.2012 10:57, schrieb Stefan Hajnoczi: > QEMU has a policy of keeping a stable guest device ABI. When new guest device > features are introduced they must not change hardware info seen by existing > guests. This is important because operating systems or applications may > "fingerprint" the hardware and refuse to run when the hardware changes. To > always get the latest guest device ABI, run with x86 machine type "pc". > > This patch hides the new VIRTIO_BLK_F_CONFIG_WCE virtio feature bit from > existing machine types. Only pc-1.2 and later will expose this feature > by default. > > For more info on the VIRTIO_BLK_F_CONFIG_WCE feature bit, see: > > commit 13e3dce068773c971ff2f19d986378c55897c4a3 > Author: Paolo Bonzini <pbonzini@redhat.com> > Date: Thu Aug 9 16:07:19 2012 +0200 > > virtio-blk: support VIRTIO_BLK_F_CONFIG_WCE > > Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with > the spec. > > Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> > Signed-off-by: Kevin Wolf <kwolf@redhat.com> > > Anthony Liguori <aliguori@us.ibm.com> reported: > > This broke qemu-test because it changed the pc-1.0 machine type: > > Setting guest RANDOM seed to 47167 > *** Running tests *** > Running test /tests/finger-print.sh... OK > --- fingerprints/pc-1.0.x86_64 2011-12-18 13:08:40.000000000 -0600 > +++ fingerprint.txt 2012-08-12 13:30:48.000000000 -0500 > @@ -55,7 +55,7 @@ > /sys/bus/pci/devices/0000:00:06.0/subsystem_device=0x0002 > /sys/bus/pci/devices/0000:00:06.0/class=0x010000 > /sys/bus/pci/devices/0000:00:06.0/revision=0x00 > -/sys/bus/pci/devices/0000:00:06.0/virtio/host-features=0x710006d4 > +/sys/bus/pci/devices/0000:00:06.0/virtio/host-features=0x71000ed4 > /sys/class/dmi/id/bios_vendor=Bochs > /sys/class/dmi/id/bios_date=01/01/2007 > /sys/class/dmi/id/bios_version=Bochs > Guest fingerprint changed for pc-1.0! > > Reported-by: Anthony Liguori <aliguori@us.ibm.com> > Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> > --- > Anthony, does this fix your test case? Looks good to me, but I think I'll wait for Anthony to check it. Kevin
On Thu, Aug 16, 2012 at 10:07 AM, Kevin Wolf <kwolf@redhat.com> wrote: > Am 16.08.2012 10:57, schrieb Stefan Hajnoczi: >> QEMU has a policy of keeping a stable guest device ABI. When new guest device >> features are introduced they must not change hardware info seen by existing >> guests. This is important because operating systems or applications may >> "fingerprint" the hardware and refuse to run when the hardware changes. To >> always get the latest guest device ABI, run with x86 machine type "pc". >> >> This patch hides the new VIRTIO_BLK_F_CONFIG_WCE virtio feature bit from >> existing machine types. Only pc-1.2 and later will expose this feature >> by default. >> >> For more info on the VIRTIO_BLK_F_CONFIG_WCE feature bit, see: >> >> commit 13e3dce068773c971ff2f19d986378c55897c4a3 >> Author: Paolo Bonzini <pbonzini@redhat.com> >> Date: Thu Aug 9 16:07:19 2012 +0200 >> >> virtio-blk: support VIRTIO_BLK_F_CONFIG_WCE >> >> Also rename VIRTIO_BLK_F_WCACHE to VIRTIO_BLK_F_WCE for consistency with >> the spec. >> >> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> >> Signed-off-by: Kevin Wolf <kwolf@redhat.com> >> >> Anthony Liguori <aliguori@us.ibm.com> reported: >> >> This broke qemu-test because it changed the pc-1.0 machine type: >> >> Setting guest RANDOM seed to 47167 >> *** Running tests *** >> Running test /tests/finger-print.sh... OK >> --- fingerprints/pc-1.0.x86_64 2011-12-18 13:08:40.000000000 -0600 >> +++ fingerprint.txt 2012-08-12 13:30:48.000000000 -0500 >> @@ -55,7 +55,7 @@ >> /sys/bus/pci/devices/0000:00:06.0/subsystem_device=0x0002 >> /sys/bus/pci/devices/0000:00:06.0/class=0x010000 >> /sys/bus/pci/devices/0000:00:06.0/revision=0x00 >> -/sys/bus/pci/devices/0000:00:06.0/virtio/host-features=0x710006d4 >> +/sys/bus/pci/devices/0000:00:06.0/virtio/host-features=0x71000ed4 >> /sys/class/dmi/id/bios_vendor=Bochs >> /sys/class/dmi/id/bios_date=01/01/2007 >> /sys/class/dmi/id/bios_version=Bochs >> Guest fingerprint changed for pc-1.0! >> >> Reported-by: Anthony Liguori <aliguori@us.ibm.com> >> Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> >> --- >> Anthony, does this fix your test case? > > Looks good to me, but I think I'll wait for Anthony to check it. Yep, we definitely need to check because I haven't run qemu-test myself. Stefan
diff --git a/hw/pc_piix.c b/hw/pc_piix.c index 0c0096f..d68dbb2 100644 --- a/hw/pc_piix.c +++ b/hw/pc_piix.c @@ -375,6 +375,10 @@ static QEMUMachine pc_machine_v1_2 = { .driver = "qxl",\ .property = "vgamem_mb",\ .value = stringify(8),\ + },{\ + .driver = "virtio-blk-pci",\ + .property = "config-wce",\ + .value = "off",\ } static QEMUMachine pc_machine_v1_1 = { diff --git a/hw/virtio-blk.c b/hw/virtio-blk.c index fd8fa90..0bc2b5e 100644 --- a/hw/virtio-blk.c +++ b/hw/virtio-blk.c @@ -533,7 +533,9 @@ static uint32_t virtio_blk_get_features(VirtIODevice *vdev, uint32_t features) features |= (1 << VIRTIO_BLK_F_BLK_SIZE); features |= (1 << VIRTIO_BLK_F_SCSI); - features |= (1 << VIRTIO_BLK_F_CONFIG_WCE); + if (s->blk->config_wce) { + features |= (1 << VIRTIO_BLK_F_CONFIG_WCE); + } if (bdrv_enable_write_cache(s->bs)) features |= (1 << VIRTIO_BLK_F_WCE); diff --git a/hw/virtio-blk.h b/hw/virtio-blk.h index 35834cf..454f445 100644 --- a/hw/virtio-blk.h +++ b/hw/virtio-blk.h @@ -104,6 +104,7 @@ struct VirtIOBlkConf BlockConf conf; char *serial; uint32_t scsi; + uint32_t config_wce; }; #define DEFINE_VIRTIO_BLK_FEATURES(_state, _field) \ diff --git a/hw/virtio-pci.c b/hw/virtio-pci.c index 5e6e09e..2a3d86f 100644 --- a/hw/virtio-pci.c +++ b/hw/virtio-pci.c @@ -886,6 +886,7 @@ static Property virtio_blk_properties[] = { #ifdef __linux__ DEFINE_PROP_BIT("scsi", VirtIOPCIProxy, blk.scsi, 0, true), #endif + DEFINE_PROP_BIT("config-wce", VirtIOPCIProxy, blk.config_wce, 0, true), DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true), DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 2), DEFINE_VIRTIO_BLK_FEATURES(VirtIOPCIProxy, host_features),