February 2010 - Devel - libvirt List Archives

[libvirt] [PATCH v2 0/9] New public API for computing baseline CPU
by Jiri Denemark 17 Feb '10

17 Feb '10

Version 2 changes: - rebased (mainly for conn argument removal) - swapped array and number of elements in array parameters - fixed absolute paths in generated RPC code - added python bindings for virConnectBaselineCPU - fixed uninitialized variable in cpuDecode, which wasn't revealed by gcc :-( This series introduces a new virConnectBaselineCPU() API call for computing baseline CPU model from a set of host CPU definitions. The call accepts a list of <cpu>...</cpu> xml definitions taken from host capabilities and returns an xml description of a guest CPU which is supported by all hosts. virsh is little bit less picky and accepts a file containing host CPU definitions. It doesn't care what is outside of the <cpu/> tag, which allows for concatenating outputs of virsh capabilities from several hosts and feeding the result to virsh cpu-baseline. This series can also be found on cpu-baseline branch of git://gitorious.org/~jirka/libvirt/jirka-staging.git In practice it works like this: # virsh cpu-baseline /dev/stdin >guest-cpu <<EOF <capabilities> <host> <cpu> <arch>x86_64</arch> <model>core2duo</model> <topology sockets='1' cores='2' threads='1'/> <feature name='lahf_lm'/> <feature name='xtpr'/> <feature name='cx16'/> <feature name='tm2'/> <feature name='est'/> <feature name='vmx'/> </cpu> </host> </capabilities> <cpu> <arch>i686</arch> <model>pentiumpro</model> <topology sockets='1' cores='2' threads='1'/> <feature name='vme'/> <feature name='pse36'/> <feature name='pni'/> <feature name='monitor'/> <feature name='ssse3'/> </cpu> <cpu> <arch>x86_64</arch> <model>phenom</model> </cpu> EOF # cat guest-cpu <cpu match='exact'> <model>qemu32</model> <feature policy='require' name='monitor'/> <feature policy='require' name='pse36'/> </cpu> Jiri Denemark (9): Functions for computing baseline CPU from a set of host CPUs Implement cpuArchBaseline in generic CPU driver Implement cpuArchBaseline in x86 CPU driver virConnectBaselineCPU public API Internal driver API for virConnectBaselineCPU virConnectBaselineCPU public API implementation Wire protocol format and dispatcher for virConnectBaselineCPU Implement cpuBaseline in remote and qemu drivers cpu-baseline command for virsh daemon/remote.c | 25 +++++++ daemon/remote_dispatch_args.h | 1 + daemon/remote_dispatch_prototypes.h | 8 ++ daemon/remote_dispatch_ret.h | 1 + daemon/remote_dispatch_table.h | 5 ++ include/libvirt/libvirt.h.in | 18 +++++ python/generator.py | 1 + python/libvirt-override-api.xml | 7 ++ python/libvirt-override.c | 52 +++++++++++++++ src/cpu/cpu.c | 123 ++++++++++++++++++++++++++++++++++- src/cpu/cpu.h | 21 ++++++- src/cpu/cpu_generic.c | 104 +++++++++++++++++++++++++++++- src/cpu/cpu_x86.c | 88 ++++++++++++++++++++++++- src/driver.h | 6 ++ src/esx/esx_driver.c | 1 + src/libvirt.c | 57 ++++++++++++++++ src/libvirt_private.syms | 2 + src/libvirt_public.syms | 1 + src/lxc/lxc_driver.c | 1 + src/opennebula/one_driver.c | 1 + src/openvz/openvz_driver.c | 1 + src/phyp/phyp_driver.c | 1 + src/qemu/qemu_driver.c | 14 ++++ src/remote/remote_driver.c | 32 +++++++++ src/remote/remote_protocol.c | 22 ++++++ src/remote/remote_protocol.h | 20 ++++++ src/remote/remote_protocol.x | 18 +++++- src/test/test_driver.c | 1 + src/uml/uml_driver.c | 1 + src/vbox/vbox_tmpl.c | 1 + src/xen/xen_driver.c | 1 + tools/virsh.c | 72 ++++++++++++++++++++ tools/virsh.pod | 8 ++ 33 files changed, 709 insertions(+), 6 deletions(-)

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[libvirt] [PATCH] vbox_tmpl.c: avoid leak on OOM error path
by Jim Meyering 17 Feb '10

17 Feb '10

We have to free def here, rather than after "cleanup:", because "cleanup:" is on the successful-return path. >From 2c7800c3560f03fd77e4a458cb0e557165faed3f Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Mon, 15 Feb 2010 17:54:15 +0100 Subject: [PATCH] vbox_tmpl.c: avoid leak on OOM error path * src/vbox/vbox_tmpl.c (vboxDomainDumpXML): Free def upon virAsprintf failure. --- src/vbox/vbox_tmpl.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/src/vbox/vbox_tmpl.c b/src/vbox/vbox_tmpl.c index 68dffd2..1fb8d56 100644 --- a/src/vbox/vbox_tmpl.c +++ b/src/vbox/vbox_tmpl.c @@ -6059,14 +6059,15 @@ static char *vboxNetworkDumpXML(virNetworkPtr network, int flags ATTRIBUTE_UNUSE if (VIR_ALLOC(def) < 0) { virReportOOMError(); goto cleanup; } if (virAsprintf(&networkNameUtf8, "HostInterfaceNetworking-%s", network->name) < 0) { virReportOOMError(); + VIR_FREE(def); goto cleanup; } PRUnichar *networkInterfaceNameUtf16 = NULL; IHostNetworkInterface *networkInterface = NULL; VBOX_UTF8_TO_UTF16(network->name, &networkInterfaceNameUtf16); -- 1.7.0.181.g41533

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Re: [libvirt] Cannot enumerate physical devices with libvirt 0.7.6
by Frédéric Grelot 17 Feb '10

17 Feb '10

Yep, here is what I get (see at the end) : 14:06:22.071: debug : do_open:1110 : name "qemu:///system" to URI components: scheme qemu opaque (null) authority (null) server (null) user (null) port 0 path /system 14:06:22.071: debug : do_open:1120 : trying driver 0 (Test) ... 14:06:22.071: debug : do_open:1126 : driver 0 Test returned DECLINED 14:06:22.071: debug : do_open:1120 : trying driver 1 (OPENVZ) ... 14:06:22.071: debug : do_open:1126 : driver 1 OPENVZ returned DECLINED 14:06:22.071: debug : do_open:1120 : trying driver 2 (VBOX) ... 14:06:22.071: debug : do_open:1126 : driver 2 VBOX returned DECLINED 14:06:22.071: debug : do_open:1120 : trying driver 3 (remote) ... 14:06:22.071: debug : do_open:1126 : driver 3 remote returned DECLINED 14:06:22.071: debug : do_open:1120 : trying driver 4 (QEMU) ... 14:06:22.071: debug : do_open:1126 : driver 4 QEMU returned SUCCESS 14:06:22.071: debug : do_open:1146 : network driver 0 Test returned DECLINED 14:06:22.071: debug : do_open:1146 : network driver 1 VBOX returned DECLINED 14:06:22.071: debug : do_open:1146 : network driver 2 remote returned DECLINED 14:06:22.071: debug : do_open:1146 : network driver 3 Network returned SUCCESS 14:06:22.071: debug : do_open:1165 : interface driver 0 Test returned DECLINED 14:06:22.071: debug : do_open:1165 : interface driver 1 remote returned DECLINED 14:06:22.072: debug : do_open:1185 : storage driver 0 Test returned DECLINED 14:06:22.072: debug : do_open:1185 : storage driver 1 VBOX returned DECLINED 14:06:22.072: debug : do_open:1185 : storage driver 2 remote returned DECLINED 14:06:22.072: debug : do_open:1185 : storage driver 3 storage returned SUCCESS 14:06:22.072: debug : do_open:1205 : node driver 0 Test returned DECLINED 14:06:22.072: debug : do_open:1205 : node driver 1 remote returned DECLINED 14:06:22.072: debug : do_open:1232 : secret driver 0 Test returned DECLINED 14:06:22.072: debug : do_open:1232 : secret driver 1 remote returned DECLINED 14:06:22.072: debug : do_open:1232 : secret driver 2 secret returned SUCCESS 14:06:22.072: debug : virConnectClose:1381 : conn=0x1eaf0b0 I think the times when I get those lines matches with my "virsh nodedev-list" requests (or something like this : virt-manager tries to create a vm, add hardware...). Does this help? Frederic. ----- "Dave Allan" <dallan(a)redhat.com> a écrit : > On 02/16/2010 03:00 AM, Frédéric Grelot wrote: > >> Daniel was referring to the libvirt udev driver--the libvirt code > that > >> > >> interacts with udev--not to udev itself, which is what you're > testing > >> > >> with udevadm. > > > > Ok, sorry... At least I ensured that udev itself is on... > > > >> In any of your logs when you have libvirt debug logging > >> turned on, do you see the message: > >> > >> Registering udev node device backend > > > > Nope, I checked in /var/log/* and libvirt.log in debug mode (which, > after 1 1/2 day of "debug" activity enabled, is already 2Gb!) > > There is no mention of udev. I think it means that the udev driver > is not loaded in libvirt? How could enable it then? (or produce some > message telling me why it is not) ? > > > > > >> These messages are the result of not being able to find the > device, > >> which is consistent with the other things you're seeing. These > are > >> all symptoms of the node device code not running. > > > > OK, I'll wait for your suggestions... > > Do you see messages like: > > > 14:35:01.849: debug : do_open:1205 : node driver 0 Test returned > DECLINED > 14:35:01.849: debug : do_open:1205 : node driver 1 ESX returned > DECLINED > 14:35:01.849: debug : do_open:1205 : node driver 2 remote returned > DECLINED > 14:35:01.849: debug : do_open:1205 : node driver 3 udevDeviceMonitor > returned SUCCESS > > in your debug log? > > > > Frederic. > > > > > >> > >>> Have you any other Idea? > >>> Frederic. > >>> > >>> > >>> ----- "Daniel P. Berrange"<berrange(a)redhat.com> a écrit : > >>> > >>>> On Fri, Feb 12, 2010 at 08:05:21PM +0100, Fr?d?ric Grelot wrote: > >>>>> Hi all, > >>>>> > >>>>> I often update my F12 box with the rawvirt repository, which > >>>>> just > >>>> installed libvirt 0.7.6. Since that, I cannot enumerate physical > >>>> devices (and thus get a beautiful error when I start one of my > vms > >>>> that should use a USB device). > >>>>> > >>>>> I don't think I changed anything else on that box, and, of > >>>>> course, I > >>>> already restarted the libvirt daemon. > >>>>> I haven't restarted the server itself, because it is currently > >>>>> used, > >>>> but I could do it if necessary... > >>>>> > >>>>> I make good use of the qemu hypervisor, and I'm looking forward > >>>>> to > >>>> solve this issue! > >>>>> > >>>>> Frederic. > >>>>> > >>>>> # libvirtd --version libvirtd (libvirt) 0.7.6 > >>>>> > >>>>> # virsh --version 0.7.6 > >>>>> > >>>>> # virsh nodedev-list error :Failed to count node devices error > >>>>> :this function is not supported by the hypervisor: > >>>> virNodeNumOfDevices > >>>> > >>>> It would appear that the udev driver failed to start - there are > >>>> probably messages in syslog about the problem > >>>> > >>>> > >>>> Regards, Daniel -- |: Red Hat, Engineering, London -o- > >>>> http://people.redhat.com/berrange/ :| |: http://libvirt.org -o- > >>>> http://virt-manager.org -o- http://ovirt.org :| |: > >>>> http://autobuild.org -o- http://search.cpan.org/~danberr/ > :| > >>>> |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 > >>>> 7D3B 9505 :| > >>> > >>> -- libvir-list mailing list libvir-list(a)redhat.com > >>> https://www.redhat.com/mailman/listinfo/libvir-list > > > > -- > > libvir-list mailing list > > libvir-list(a)redhat.com > > https://www.redhat.com/mailman/listinfo/libvir-list

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Re: [libvirt] Cannot enumerate physical devices with libvirt 0.7.6
by Frédéric Grelot 17 Feb '10

17 Feb '10

The udev driver is actually fully loaded, I even entered "udevadm monitor" in a console, and it reacted as expected when I plugged/unplugged an usb mouse... There is nothing about it in dmesg/boot/message.log, nor libvirt.log (I set up libvirt daemon to log at debug level in /var/log/libvirt/libvirt.log). By the way, I noticed that libvirt generates tons of "error : qemuMonitorTextGetBlockStatsInfo:698 : invalid argument in no stats found for device virtio-diskX" while virt-manager is running (it stops as soon as I stop virt-manager). Is it linked with the bug I saw on the list about libvirt taking over memory after time isn't it? Have you any other Idea? Frederic. ----- "Daniel P. Berrange" <berrange(a)redhat.com> a écrit : > On Fri, Feb 12, 2010 at 08:05:21PM +0100, Fr?d?ric Grelot wrote: > > Hi all, > > > > I often update my F12 box with the rawvirt repository, which just > installed libvirt 0.7.6. Since that, I cannot enumerate physical > devices (and thus get a beautiful error when I start one of my vms > that should use a USB device). > > > > I don't think I changed anything else on that box, and, of course, I > already restarted the libvirt daemon. > > I haven't restarted the server itself, because it is currently used, > but I could do it if necessary... > > > > I make good use of the qemu hypervisor, and I'm looking forward to > solve this issue! > > > > Frederic. > > > > # libvirtd --version > > libvirtd (libvirt) 0.7.6 > > > > # virsh --version > > 0.7.6 > > > > # virsh nodedev-list > > error :Failed to count node devices > > error :this function is not supported by the hypervisor: > virNodeNumOfDevices > > It would appear that the udev driver failed to start - there are > probably > messages in syslog about the problem > > > Regards, > Daniel > -- > |: Red Hat, Engineering, London -o- > http://people.redhat.com/berrange/ :| > |: http://libvirt.org -o- http://virt-manager.org -o- > http://ovirt.org :| > |: http://autobuild.org -o- > http://search.cpan.org/~danberr/ :| > |: GnuPG: 7D3B9505 -o- F3C9 553F A1DA 4AC2 5648 23C1 B3DF F742 7D3B > 9505 :|

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[libvirt] [PATCH] vshCommandParse: placate coverity
by Jim Meyering 17 Feb '10

17 Feb '10

Here are two patches to avoid semblance of a leak. One adds a useless use of VIR_FREE. The other adds an assertion that the pointer to would-be-leaked storage is NULL. There's already an assertion in this file, so no need to add an "#include ...". Take your pick. >From 2070262e7f1a4803e06a6f75bd96091c5754164d Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 16 Feb 2010 14:34:48 +0100 Subject: [PATCH] vshCommandParse: placate coverity There is no real leak here, but Coverity-Prevent thinks there is. It does not see that while there are four ways to return from vshCommandGetToken with VSH_TK_END, none of them results in allocation of a result. * tools/virsh.c (vshCommandParse): Add a (currently) useless VIR_FREE, to ensure that we never leak when vshCommandGetToken returns VSH_TK_END. --- tools/virsh.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 7db48d9..4ffa154 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -8222,8 +8222,10 @@ vshCommandParse(vshControl *ctl, char *cmdstr) str = end; - if (tk == VSH_TK_END) + if (tk == VSH_TK_END) { + VIR_FREE(tkdata); break; + } if (tk == VSH_TK_ERROR) goto syntaxError; -- 1.7.0.181.g41533 >From 98b0c148d7fd7e11eed7786189db60b485612b51 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 16 Feb 2010 14:34:48 +0100 Subject: [PATCH] vshCommandParse: placate coverity * tools/virsh.c (vshCommandParse): Inform static analyzers that there is no risk of leak when vshCommandGetToken returns VSH_TK_END. --- tools/virsh.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/tools/virsh.c b/tools/virsh.c index 7db48d9..5c45d1c 100644 --- a/tools/virsh.c +++ b/tools/virsh.c @@ -8222,8 +8222,10 @@ vshCommandParse(vshControl *ctl, char *cmdstr) str = end; - if (tk == VSH_TK_END) + if (tk == VSH_TK_END) { + assert (tkdata == NULL); break; + } if (tk == VSH_TK_ERROR) goto syntaxError; -- 1.7.0.181.g41533

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[libvirt] [PATCH] qemuMonitorTextAddUSBDisk: avoid unconditional leak
by Jim Meyering 17 Feb '10

17 Feb '10

First the patch, then the (fixed) function: >From d3f0ee1ee11ca5f3709168fdc4e6eb1c56fdfbc0 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 16 Feb 2010 13:51:38 +0100 Subject: [PATCH] qemuMonitorTextAddUSBDisk: avoid unconditional leak * src/qemu/qemu_monitor_text.c (qemuMonitorTextAddUSBDisk): Free command output buffer. --- src/qemu/qemu_monitor_text.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c index c71bf1d..62ffcc6 100644 --- a/src/qemu/qemu_monitor_text.c +++ b/src/qemu/qemu_monitor_text.c @@ -1229,6 +1229,7 @@ int qemuMonitorTextAddUSBDisk(qemuMonitorPtr mon, cleanup: VIR_FREE(cmd); VIR_FREE(safepath); + VIR_FREE(info); return ret; } -- 1.7.0.181.g41533 int qemuMonitorTextAddUSBDisk(qemuMonitorPtr mon, const char *path) { char *cmd = NULL; char *safepath; int ret = -1; char *info = NULL; safepath = qemuMonitorEscapeArg(path); if (!safepath) { virReportOOMError(); return -1; } if (virAsprintf(&cmd, "usb_add disk:%s", safepath) < 0) { virReportOOMError(); goto cleanup; } if (qemuMonitorCommand(mon, cmd, &info) < 0) { qemuReportError(VIR_ERR_INTERNAL_ERROR, "%s", _("cannot run monitor command to add usb disk")); goto cleanup; } /* If the command failed qemu prints: * Could not add ... */ if (strstr(info, "Could not add ")) { qemuReportError(VIR_ERR_OPERATION_FAILED, _("unable to add USB disk %s: %s"), path, info); goto cleanup; } ret = 0; cleanup: VIR_FREE(cmd); VIR_FREE(safepath); VIR_FREE(info); return ret; }

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[libvirt] [PATCH] tests: avoid NULL deref upon OOM failure
by Jim Meyering 17 Feb '10

17 Feb '10

Pretty obvious: >From 3e79d8839c5051461197a7c484adb32f7f04377a Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 16 Feb 2010 09:36:57 +0100 Subject: [PATCH] tests: avoid NULL deref upon OOM failure * tests/qemuxml2argvtest.c (testCompareXMLToArgvFiles): Handle malloc failure. --- tests/qemuxml2argvtest.c | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-) diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index 3ee71a3..aa42f99 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -98,7 +98,8 @@ static int testCompareXMLToArgvFiles(const char *xml, len += strlen(*tmp) + 1; tmp++; } - actualargv = malloc(sizeof(*actualargv)*len); + if ((actualargv = malloc(sizeof(*actualargv)*len)) == NULL) + goto fail; actualargv[0] = '\0'; tmp = qenv; while (*tmp) { -- 1.7.0.181.g41533

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[libvirt] [PATCH] qemuInitPasswords: avoid unconditional leak
by Jim Meyering 17 Feb '10

17 Feb '10

A successful getVolumeQcowPassphrase allocates "secret". Nothing freed it. >From 2aa6d3c4254f587133e473f4d193ccb023507665 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 16 Feb 2010 09:22:02 +0100 Subject: [PATCH] qemuInitPasswords: avoid unconditional leak * src/qemu/qemu_driver.c (qemuInitPasswords): Free pass-phrase buffer. --- src/qemu/qemu_driver.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 03feaf4..e8b7cf6 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -1733,34 +1733,35 @@ qemuInitPasswords(virConnectPtr conn, for (i = 0 ; i < vm->def->ndisks ; i++) { char *secret; size_t secretLen; if (!vm->def->disks[i]->encryption || !vm->def->disks[i]->src) continue; if (getVolumeQcowPassphrase(conn, vm->def->disks[i], &secret, &secretLen) < 0) goto cleanup; qemuDomainObjEnterMonitorWithDriver(driver, vm); ret = qemuMonitorSetDrivePassphrase(priv->mon, vm->def->disks[i]->info.alias, secret); + VIR_FREE(secret); qemuDomainObjExitMonitorWithDriver(driver, vm); if (ret < 0) goto cleanup; } } cleanup: return ret; } #define QEMU_PCI_VENDOR_INTEL 0x8086 #define QEMU_PCI_VENDOR_LSI_LOGIC 0x1000 #define QEMU_PCI_VENDOR_REDHAT 0x1af4 #define QEMU_PCI_VENDOR_CIRRUS 0x1013 #define QEMU_PCI_VENDOR_REALTEK 0x10ec #define QEMU_PCI_VENDOR_AMD 0x1022 -- 1.7.0.181.g41533

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[libvirt] [PATCH] qemuMonitorTextAddDevice: avoid unconditional leak
by Jim Meyering 17 Feb '10

17 Feb '10

Here's the patch (entire function below): >From 1ee0edab5356ca8cd84a88e4e4a2e4f3cd916f57 Mon Sep 17 00:00:00 2001 From: Jim Meyering <meyering(a)redhat.com> Date: Tue, 16 Feb 2010 08:22:34 +0100 Subject: [PATCH] qemuMonitorTextAddDevice: avoid unconditional leak * src/qemu/qemu_monitor_text.c (qemuMonitorTextAddDevice): Free the device name buffer. --- src/qemu/qemu_monitor_text.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-) diff --git a/src/qemu/qemu_monitor_text.c b/src/qemu/qemu_monitor_text.c index e993699..c71bf1d 100644 --- a/src/qemu/qemu_monitor_text.c +++ b/src/qemu/qemu_monitor_text.c @@ -2087,6 +2087,7 @@ int qemuMonitorTextAddDevice(qemuMonitorPtr mon, cleanup: VIR_FREE(cmd); VIR_FREE(reply); + VIR_FREE(safedev); return ret; } -- 1.7.0.181.g41533 For reference, here's the entire function: int qemuMonitorTextAddDevice(qemuMonitorPtr mon, const char *devicestr) { char *cmd = NULL; char *reply = NULL; char *safedev; int ret = -1; if (!(safedev = qemuMonitorEscapeArg(devicestr))) { virReportOOMError(); goto cleanup; } if (virAsprintf(&cmd, "device_add %s", safedev) < 0) { virReportOOMError(); goto cleanup; } if (qemuMonitorCommand(mon, cmd, &reply) < 0) { qemuReportError(VIR_ERR_OPERATION_FAILED, _("cannot attach %s device"), devicestr); goto cleanup; } if (STRNEQ(reply, "")) { qemuReportError(VIR_ERR_OPERATION_FAILED, _("adding %s device failed: %s"), devicestr, reply); goto cleanup; } ret = 0; cleanup: VIR_FREE(cmd); VIR_FREE(reply); VIR_FREE(safedev); return ret; }

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[libvirt] PATCH [0/3] Volume zeroing
by David Allan 17 Feb '10

17 Feb '10

The following patches implement overwriting a volume with zeros when the volume is deleted. The zeroing happens before the delete, so it works for storage backends that don't support actually deleting volumes as well as the ones that do. The intent is that any future VM assigned that volume will not be able to recover any data belonging to the previous VM. It is not intended to prevent attackers with physical access to the medium from recovering data--it simply writes a single pass of zeros over the medium. If the filesystem containing the volume supports the fiemap ioctl and the volume is a sparse file, the volume zeroing code attempts to use fiemap to locate the mapped extents. It does not attempt to zero a sparse file if it cannot use fiemap. Such an operation could take an essentially unbounded amount of time. Since the volume is being deleted, zeroing has less value in the context of backends that support delete, but does provide value with storage backends that do not zero volumes if they are deleted and recreated. Dave

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