From: "Michael S. Tsirkin" <mst@redhat.com>
To: Sheng Yang <sheng@linux.intel.com>
Cc: Avi Kivity <avi@redhat.com>,
Marcelo Tosatti <mtosatti@redhat.com>,
kvm@vger.kernel.org
Subject: Re: [PATCH 1/3] KVM: Emulation MSI-X mask bits for assigned devices
Date: Tue, 12 Oct 2010 20:30:30 +0200 [thread overview]
Message-ID: <20101012183030.GD30997@redhat.com> (raw)
In-Reply-To: <201010121449.58332.sheng@linux.intel.com>
On Tue, Oct 12, 2010 at 02:49:58PM +0800, Sheng Yang wrote:
> On Monday 11 October 2010 18:01:00 Michael S. Tsirkin wrote:
> > On Mon, Oct 11, 2010 at 05:28:30PM +0800, Sheng Yang wrote:
> > > On Sunday 03 October 2010 19:12:47 Michael S. Tsirkin wrote:
> > > > On Tue, Sep 28, 2010 at 05:44:10PM +0800, Sheng Yang wrote:
> > > > > This patch enable per-vector mask for assigned devices using MSI-X.
> > > > >
> > > > > Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> > > >
> > > > I think I see an issue here, noted below. Some general comments:
> > > > - The mask bit seems broken for injecting interrupts from
> > > >
> > > > userspace (with interrupts/ioctls).
> > > > I think we must test it on injection path.
> > >
> > > I am not quite understand how it related to userspace interrupt injection
> > > here... This patch only cover assigned devices for now.
> >
> > Well, this is a kernel/userspace interface, if it's broken for userspace
> > injection now we'll have to go through pain to fix it in a compatible
> > way later when we want to use it for userspace injection.
> > You might want to ask why we want the kernel to support making
> > userspace-injected interrupts when userspace can just avoid injecting
> > them, and the answer would be that with irqfd the injection might be
> > handled in a separate process.
>
> OK, I've understood how it related to userspace interrupt injection. But I still
> can't see why the interface is broken...
That's easy to explain: mask vector, then inject interrupt with an ioctl or irqfd:
it still goes in even though it's masked.
--
MST
next prev parent reply other threads:[~2010-10-12 18:36 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-09-28 9:44 [PATCH 0/3] Emulate MSI-X mask bits for assigned devices Sheng Yang
2010-09-28 9:44 ` [PATCH 1/3] KVM: Emulation " Sheng Yang
2010-09-28 13:36 ` Michael S. Tsirkin
2010-09-29 1:17 ` Sheng Yang
2010-09-30 16:25 ` Marcelo Tosatti
2010-09-29 8:36 ` Avi Kivity
2010-09-30 5:41 ` Sheng Yang
2010-10-03 13:03 ` Avi Kivity
2010-10-11 9:32 ` Sheng Yang
2010-09-30 16:18 ` Marcelo Tosatti
2010-10-11 9:49 ` Sheng Yang
2010-10-11 17:11 ` Marcelo Tosatti
2010-10-03 11:12 ` Michael S. Tsirkin
2010-10-11 9:28 ` Sheng Yang
2010-10-11 10:01 ` Michael S. Tsirkin
2010-10-12 6:49 ` Sheng Yang
2010-10-12 18:28 ` Michael S. Tsirkin
2010-10-13 1:03 ` Sheng Yang
2010-10-13 10:35 ` Michael S. Tsirkin
2010-10-12 18:30 ` Michael S. Tsirkin [this message]
2010-10-13 0:58 ` Sheng Yang
2010-10-13 12:03 ` Michael S. Tsirkin
2010-09-28 9:44 ` [PATCH 2/3] qemu-kvm: device assignment: Some clean up for MSI-X code Sheng Yang
2010-09-28 9:44 ` [PATCH 3/3] qemu-kvm: device assignment: emulate MSI-X mask bits Sheng Yang
2010-09-30 16:44 ` [PATCH 0/3] Emulate MSI-X mask bits for assigned devices Marcelo Tosatti
2010-10-11 9:34 ` Sheng Yang
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