Re: [PATCH v1 2/2] hw/mem/cxl_type3: allocate more vectors for MSI-X

[Jonathan Cameron via <qemu-devel@nongnu.org>]

On Tue, 28 Nov 2023 09:27:28 +0900
Hyeonggon Yoo <42.hyeyoo@gmail.com> wrote:

> On Tue, Nov 28, 2023 at 2:53 AM Davidlohr Bueso <dave@stgolabs.net> wrote:
> >
> > On Mon, 27 Nov 2023, Hyeonggon Yoo wrote:
> >  
> > >commit 43efb0bfad2b ("hw/cxl/mbox: Wire up interrupts for background
> > >completion") enables notifying background command completion via MSI-X
> > >interrupt (vector number 9).
> > >
> > >However, the commit uses vector number 9 but the maximum number of
> > >entries is less thus resulting in error below. Fix it by passing
> > >nentries = 10 when calling msix_init_exclusive_bar().  
> >
> > Hmm yeah this was already set to 10 in Jonathan's tree, thanks for reporting.  
> 
> Oh, yeah, it's based on the mainline tree. I should have checked Jonathan's.
> 
> hmm it's already 10 there but vector number 9 is already being used by PCIe DOE.
> So I think it should change msix_num = 11 and use vector number 10 for
> background command completion interrupt instead?
> 
> https://gitlab.com/jic23/qemu/-/commit/2823f19188664a6d48a965ea8170c9efa23cddab

Whilst I clearly messed up a rebase as this wasn't intended, it should be fine
to have multiple things sharing a vector.

On my todo list is making the case of too few vectors being available work for
all the cases in which case everything may end up on one vector.
So we do need to expand the vectors to cover what we are asking for, but
moving this to 11 is a nice to have rather than required.

Jonathan

> 
> Thanks!
> 
> --
> Hyeonggon