Re: [PATCH v2 06/29] vfio: enable per-IRQ MSI-X masking

[John Levon <john.levon@nutanix.com>]

On Wed, May 28, 2025 at 01:16:32PM -0400, Steven Sistare wrote:

> > On 5/20/25 17:03, John Levon wrote:
> > > If VFIO_IRQ_INFO_MASKABLE is set for VFIO_PCI_MSIX_IRQ_INDEX, record
> > > this in ->can_mask_msix, and use it to individually mask MSI-X
> > > interrupts as needed.
> > > 
> > > Originally-by: John Johnson <john.g.johnson@oracle.com>
> > > Signed-off-by: Elena Ufimtseva <elena.ufimtseva@oracle.com>
> > > Signed-off-by: Jagannathan Raman <jag.raman@oracle.com>
> > > Signed-off-by: John Levon <john.levon@nutanix.com>
> > 
> > This one conflicts with the "live update" series. We will address it later.
> 
> AFAICT there is only a trivial conflict versus my patch
> 
>   vfio/pci: vfio_vector_init
>   https://urldefense.proofpoint.com/v2/url?u=https-3A__lore.kernel.org_qemu-2Ddevel_1747063973-2D124548-2D17-2Dgit-2Dsend-2Demail-2Dsteven.sistare-40oracle.com_&d=DwIDaQ&c=s883GpUCOChKOHiocYtGcg&r=v7SNLJqx7b9Vfc7ZO82Wg4nnZ8O5XkACFQ30bVKxotI&m=us5Q7sdvPzuJ8qd0-KHuGcuoxQPDRJYPJ9dFmIeHxb0i8WnpPqrLiu3UuGSoq95U&s=Pd5fbQX8J7_CHHWD16ZuvXKJ13kipONxypuqS_cjGI0&e=
> 
> because I extract a handful of lines from vfio_msix_vector_do_use into a
> subroutine, at the same place vfio-user has added a local variable new_vec,
> but the new code will simply be:
> 
> vfio_msix_vector_do_use
>     if (!vector->use) {
>         new_vec = true;
>         vfio_pci_vector_init(vdev, nr);
>     }

I'll take a look when rebasing on top of CPR and ask you if I get stuck.

> Also, for now I am assuming that if vfio-user is being used, then I will add
> a CPR blocker.

That's fine (and I will take care of it in my series), but I *think* this
per-interrupt masking can apply outside of vfio-user.

regards
john