On Tue, Mar 29, 2022 at 08:13:57PM +0200, Thomas Gleixner wrote: > On Tue, Mar 29 2022 at 10:37, Michael S. Tsirkin wrote: > > On Tue, Mar 29, 2022 at 10:35:21AM +0200, Thomas Gleixner wrote: > > We are trying to fix the driver since at the moment it does not > > have the dev->ok flag at all. > > > > And I suspect virtio is not alone in that. > > So it would have been nice if there was a standard flag > > replacing the driver-specific dev->ok above, and ideally > > would also handle the case of an interrupt triggering > > too early by deferring the interrupt until the flag is set. > > > > And in fact, it does kind of exist: IRQF_NO_AUTOEN, and you would call > > enable_irq instead of dev->ok = true, except > > - it doesn't work with affinity managed IRQs > > - it does not work with shared IRQs > > > > So using dev->ok as you propose above seems better at this point. > > Unless there is a big enough amount of drivers which could make use of a > generic mechanism for that. > > >> If any driver does this in the wrong order, then the driver is > >> broken. > > > > I agree, however: > > $ git grep synchronize_irq `git grep -l request_irq drivers/net/`|wc -l > > 113 > > $ git grep -l request_irq drivers/net/|wc -l > > 397 > > > > I suspect there are more drivers which in theory need the > > synchronize_irq dance but in practice do not execute it. > > That really depends on when the driver requests the interrupt, when > it actually enables the interrupt in the device itself This last point does not matter since we are talking about protecting against buggy/malicious devices. They can inject the interrupt anyway even if driver did not configure it. > and how the > interrupt service routine works. > > So just doing that grep dance does not tell much. You really have to do > a case by case analysis. > > Thanks, > > tglx I agree. In fact, at least for network the standard approach is to request interrupts in the open call, virtio net is unusual in doing it in probe. We should consider changing that. Jason? -- MST _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
