On Wed, Jul 21, 2021 at 10:14:25PM +0200, Thomas Gleixner wrote: > https://lore.kernel.org/r/87o8bxcuxv.ffs@xxxxxxxxxxxxxxxxxxxxxxx > > TLDR: virtio allocates ONE irq on msix_enable() and then when the guest > actually unmasks another entry (e.g. request_irq()), it tears down the > allocated one and set's up two. On the third one this repeats .... > > There are only two options: > > 1) allocate everything upfront, which is undesired > 2) append entries, which might need locking, but I'm still trying to > avoid that > > There is another problem vs. vector exhaustion which can't be fixed that > way, but that's a different story. FTI, NVMe is similar. We need one IRQ to setup the admin queue, which is used to query/set how many I/O queues are supported. Just two steps though and not unbound.
