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 <[email protected]>
> ---
> 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
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