From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:36004) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T2SAa-0002Di-3n for qemu-devel@nongnu.org; Fri, 17 Aug 2012 15:25:21 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1T2SAY-0002yI-FS for qemu-devel@nongnu.org; Fri, 17 Aug 2012 15:25:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31357) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1T2SAY-0002yC-70 for qemu-devel@nongnu.org; Fri, 17 Aug 2012 15:25:18 -0400 From: Kevin Wolf Date: Fri, 17 Aug 2012 21:25:08 +0200 Message-Id: <1345231508-7633-5-git-send-email-kwolf@redhat.com> In-Reply-To: <1345231508-7633-1-git-send-email-kwolf@redhat.com> References: <1345231508-7633-1-git-send-email-kwolf@redhat.com> Subject: [Qemu-devel] [PATCH 4/4] virtio-blk: hide VIRTIO_BLK_F_CONFIG_WCE from old machine types List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: anthony@codemonkey.ws Cc: kwolf@redhat.com, qemu-devel@nongnu.org From: 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 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 Signed-off-by: Kevin Wolf Anthony Liguori 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 Signed-off-by: Stefan Hajnoczi Signed-off-by: Kevin Wolf --- hw/pc_piix.c | 4 ++++ hw/virtio-blk.c | 4 +++- hw/virtio-blk.h | 1 + hw/virtio-pci.c | 1 + 4 files changed, 9 insertions(+), 1 deletions(-) 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), -- 1.7.6.5