Hi Alex, On 2/6/2024 2:03 PM, Alex Williamson wrote: > On Tue, 6 Feb 2024 13:46:37 -0800 > Reinette Chatre <reinette.chatre@xxxxxxxxx> wrote: > >> Hi Alex, >> >> On 2/5/2024 2:35 PM, Alex Williamson wrote: >>> On Thu, 1 Feb 2024 20:57:09 -0800 >>> Reinette Chatre <reinette.chatre@xxxxxxxxx> wrote: >> >> .. >> >>>> @@ -715,13 +724,13 @@ static int vfio_pci_set_intx_trigger(struct vfio_pci_core_device *vdev, >>>> if (is_intx(vdev)) >>>> return vfio_irq_set_block(vdev, start, count, fds, index); >>>> >>>> - ret = vfio_intx_enable(vdev); >>>> + ret = vfio_intx_enable(vdev, start, count, index); >>> >>> Please trace what happens when a user calls SET_IRQS to setup a trigger >>> eventfd with start = 0, count = 1, followed by any other combination of >>> start and count values once is_intx() is true. vfio_intx_enable() >>> cannot be the only place we bounds check the user, all of the INTx >>> callbacks should be an error or nop if vector != 0. Thanks, >>> >> >> Thank you very much for catching this. I plan to add the vector >> check to the device_name() and request_interrupt() callbacks. I do >> not think it is necessary to add the vector check to disable() since >> it does not operate on a range and from what I can tell it depends on >> a successful enable() that already contains the vector check. Similar, >> free_interrupt() requires a successful request_interrupt() (that will >> have vector check in next version). >> send_eventfd() requires a valid interrupt context that is only >> possible if enable() or request_interrupt() succeeded. > > Sounds reasonable. > >> If user space creates an eventfd with start = 0 and count = 1 >> and then attempts to trigger the eventfd using another combination then >> the changes in this series will result in a nop while the current >> implementation will result in -EINVAL. Is this acceptable? > > I think by nop, you mean the ioctl returns success. Was the call a > success? Thanks, Yes, I mean the ioctl returns success without taking any action (nop). It is not obvious to me how to interpret "success" because from what I understand current INTx and MSI/MSI-x are behaving differently when considering this flow. If I understand correctly, INTx will return an error if user space attempts to trigger an eventfd that has not been set up while MSI and MSI-x will return 0. I can restore existing INTx behavior by adding more logic and a return code to the send_eventfd() callback so that the different interrupt types can maintain their existing behavior. Reinette
