Re: [PATCH 3/3] KVM: Enable MSI-X for KVM assigned device

Sheng Yang
2009-02-12T06:04:16Z

On Wednesday 11 February 2009 20:48:55 Avi Kivity wrote:
> Sheng Yang wrote:
> > This patch finally enable MSI-X.
> >
> > What we need for MSI-X:
> > 1. Intercept one page in MMIO region of device. So that we can get guest
> > desired MSI-X table and set up the real one. Now this have been done by
> > guest, and transfer to kernel using ioctl KVM_SET_MSIX_NR and
> > KVM_SET_MSIX_ENTRY.
>
> Looking at the patch, you're doing that in userspace. Good.
>
> > 2. The PCI spec allowed to change MSI-X table dynamically. That means,
> > the OS can enable MSI-X, then mask one MSI-X entry, modify it, and unmask
> > it. The patch didn't support this, and Linux also don't work in this way.
>
> What about Windows?

Not sure. Don't have Windows driver to test... And only Vista and later
support MSI/MSI-X, not sure it would be so aggressive... We can add some debug
if such condition happened.

--
regards
Yang, Sheng