On Wed, Jul 16, 2025 at 02:17:46PM +0100, Mark Cave-Ayland wrote:
The hardware UUID (hwuuid) element provides a mechanism to supply an external UUID to the guest, as opposed to the libvirt domain UUID. This is to allow for the scenario whereby a domain can be stopped, cloned and then started as a new domain without altering the guest-visible UUID.
Add the element, documentation and core code for the hwuuid feature along with an implementation for the QEMU driver.
Signed-off-by: Mark Cave-Ayland <mark.caveayland@nutanix.com> --- docs/formatdomain.rst | 7 ++++++ src/conf/domain_conf.c | 38 ++++++++++++++++++++++++++++--- src/conf/domain_conf.h | 1 + src/conf/schemas/domaincommon.rng | 5 ++++ src/qemu/qemu_command.c | 6 ++++- 5 files changed, 53 insertions(+), 4 deletions(-)
diff --git a/docs/formatdomain.rst b/docs/formatdomain.rst index 9a2f065590..7b10dfa3da 100644 --- a/docs/formatdomain.rst +++ b/docs/formatdomain.rst @@ -54,6 +54,13 @@ General metadata
:since:`Since 0.8.7`, it is also possible to provide the UUID via a `SMBIOS System Information`_ specification. +``hwuuid`` + The optional ``hwuuid`` element can be used to supply an alternative UUID for + identifying the virtual machine from the domain ``uuid`` above. The difference + between using the ``hwuuid`` element and simply providing an alternative UUID + via a `SMBIOS System Information`_ specification is that the ``hwuuid`` affects + all devices that expose the UUID to the guest. + :since:`Since 11.6.0 QEMU/KVM only` ``genid`` :since:`Since 4.4.0`, the ``genid`` element can be used to add a Virtual Machine Generation ID which exposes a 128-bit, cryptographically random, diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c index bfc62b6270..63603ca527 100644 --- a/src/conf/domain_conf.c +++ b/src/conf/domain_conf.c @@ -13098,6 +13098,7 @@ static int virSysinfoSystemParseXML(xmlNodePtr node, xmlXPathContextPtr ctxt, virSysinfoSystemDef **sysdef, + unsigned char *hwUUID, unsigned char *domUUID, bool uuid_generated) { @@ -13122,11 +13123,18 @@ virSysinfoSystemParseXML(xmlNodePtr node, } if (uuid_generated) { memcpy(domUUID, uuidbuf, VIR_UUID_BUFLEN); - } else if (memcmp(domUUID, uuidbuf, VIR_UUID_BUFLEN) != 0) { + } else if (!virUUIDIsValid(hwUUID) && + memcmp(domUUID, uuidbuf, VIR_UUID_BUFLEN) != 0) { virReportError(VIR_ERR_XML_DETAIL, "%s", _("UUID mismatch between <uuid> and <sysinfo>")); return -1; } + if (virUUIDIsValid(hwUUID) && + memcmp(hwUUID, uuidbuf, VIR_UUID_BUFLEN) != 0) { + virReportError(VIR_ERR_XML_DETAIL, "%s", + _("UUID mismatch between <hwuuid> and <sysinfo>")); + return -1; + }
I think it'd be slightly clearer to re-arrange the order and nesting here if (uuid_generated) { ... } else if (virUUIDIsValid(hwUUID)) { if (memcmp(....)) { ...err } } else { if (memcmp(....)) { ...err } } With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|