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Date: Wed, 6 Oct 2010 22:59:23 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Bruce Edge <bruce.edge@gmail.com>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xensource.com, hpa@zytor.com,
        alex.williamson@redhat.com, x86@kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Jesse Barnes <jbarnes@virtuousgeek.org>,
        Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Subject: Re: [Xen-devel] Re: [PATCH 16/20] x86: Introduce x86_msi_ops
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On Thu, Sep 23, 2010 at 04:18:42PM -0700, Bruce Edge wrote:
> On Thu, Sep 23, 2010 at 7:48 AM, Konrad Rzeszutek Wilk
> <konrad.wilk@oracle.com> wrote:
> > On Tue, Aug 31, 2010 at 02:31:40PM -0400, Konrad Rzeszutek Wilk wrote:
> >> On Wed, Aug 04, 2010 at 02:19:11PM -0400, Konrad Rzeszutek Wilk wrote:
> >> > From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> >> >
> >> > Introduce an x86 specific indirect mechanism to setup MSIs.
> >> > The MSI setup functions become function pointers in an x86_msi_ops
> >> > struct, that defaults to the implementation in io_apic.c
> >>
> >> Hey Peter,
> >>
> >> I was wondering if you have time to take a look at this?
> >
> > ping?
> >>
> >> The patchset introduces a driver which takes care of allowing
> >> pci_conf_read/write in a virtualized environements with PCI
> >> passthrough devices. Unfortunatly for MSI operations that is not
> >> so simple, so this patch alongside with the previous one
> >> (https://patchwork.kernel.org/patch/117105/)
> >> expands the arch_* calls. This makes it possible to register on top
> >> of the native callback (the virtualized ones can), if required.
> >>
> 
> Is this patch required for PCI passthrough devices that use MSI interrupts?

Yes. And also for MSI-X. However, I've just posted a new updated mechanism based
on Thomas's idea - which is superior to this one.

> 
> I'm wondering because I'm seeing drivers for PCI passthrough  are able
> to init the MSI interrupts OK, but never get any interrupts with pvops
> domU kernels.

The problem you are seeing is different, I think we can narrow it down
to the dom0 doing something wacked.