If the MSI-X table entry 0 is mapped to queue 0, and queue 0 is offloaded to a vhost backend, and later the guest maps table entry 1 to queue 0, we will need to find out the iqrfd of table entry 1, and send a message to the vhost backend to update the irqfd. This is much more complicated than just updating table entry 0, which only involves updating the GSI table at the VMM side.
For now we simply prevent such changes if a queue is already mapped to an MSI-X entry that is linked to an irqfd.
If the MSI-X table entry 0 is mapped to queue 0, and queue 0 is offloaded to a vhost backend, and later the guest maps table entry 1 to queue 0, we will need to find out the iqrfd of table entry 1, and send a message to the vhost backend to update the irqfd. This is much more complicated than just updating table entry 0, which only involves updating the GSI table at the VMM side.
For now we simply prevent such changes if a queue is already mapped to an MSI-X entry that is linked to an irqfd.