On Wed, May 13, 2026 at 12:14:49PM +0000, Anirudh Rayabharam wrote:
> On Thu, May 07, 2026 at 03:43:43PM +0000, Stanislav Kinsburskii wrote:
> > In mshv_irqfd_assign(), the level-triggered validation for resample
> > irqfds checks irqfd_lapic_irq.lapic_control.level_triggered before
> > mshv_irqfd_update() has populated the field. Since the irqfd struct is
> > zero-allocated, level_triggered is always 0 at that point, causing the
> > check to always reject resample irqfds with -EINVAL. This makes
> > level-triggered interrupt resampling — used to avoid interrupt storms
> > with assigned devices — completely non-functional.
>
> What bugs would this manifest as? Why haven't we seen any such bugs so
> far?
>
This patch fixes a logical error.
Whtout the change this hunk always fails:
if (args->flags & BIT(MSHV_IRQFD_BIT_RESAMPLE) &&
!irqfd->irqfd_lapic_irq.lapic_control.level_triggered) {
and the reason we never seen it as that we never used
register_irqfd_with_resample() function of the mshv crate.
Thanks,
Stanislav
> Thanks,
> Anirudh.
