Re: [PATCH v2 1/3] qemu: Reflect MAC address change in live domain XML
On Tue, Mar 18, 2025 at 02:58:18PM +0100, Michal Privoznik via Devel wrote:
From: Michal Privoznik <mprivozn(a)redhat.com>
If a guest changes MAC address on its vNIC, then QEMU emits
NIC_RX_FILTER_CHANGED event (the event is emitted in other cases
too, but that's not important right now). Now, domain XML allows
users to chose whether to trust these events or not:
<interface trustGuestRxFilters='yes|no'/>
For the 'no' case no action is performed and the event is
ignored. But for the 'yes' case, some host side features of
corresponding vNIC (well tap/macvtap device) are tweaked to
reflect changed MAC address. But what is missing is reflecting
this new MAC address in domain XML.
Basically, what happens is: the host sees traffic with new MAC
address, all tools inside the guest see the new MAC address
(including 'virsh domifaddr --source agent') which makes it
harder to match device in the guest with the one in the domain
XML.
Therefore, report this new MAC address as another attribute of
the <mac/> element:
<mac address="52:54:00:a4:6f:91"
guestAddress="00:11:22:33:44:55"/>
IIUC, the "guestAddress" also influences things on the host - the
macvtap device seems to get re-programmed with the MAC, so perhaps
this is a slightly misleading name.
How about 'activeAddress' / 'liveAddress' / 'currentAddress'
With regards,
Daniel
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