lkml.org 
[lkml]   [2009]   [Apr]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [KVM PATCH v3 2/2] kvm: add support for irqfd via eventfd-notification interface
On Mon, Apr 27, 2009 at 02:33:34PM -0400, Gregory Haskins wrote:
> This allows an eventfd to be registered as an irq source with a guest. Any
> signaling operation on the eventfd (via userspace or kernel) will inject
> the registered GSI at the next available window.
>
> Signed-off-by: Gregory Haskins <ghaskins@novell.com>

If we ever want to use this with e.g. MSI-X emulation in guest, and want
to be stricly compliant to MSI-X, we'll need a way for guest to mask
interrupts, and for host to report that a masked interrupt is pending.
Ideally, all this will be doable with a couple of mmapped pages to avoid
vmexits/system calls.

> +static void
> +irqfd_inject(struct work_struct *work)
> +{
> + struct _irqfd *irqfd = container_of(work, struct _irqfd, work);
> + struct kvm *kvm = irqfd->kvm;
> +
> + mutex_lock(&kvm->lock);
> + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 1);
> + kvm_set_irq(kvm, KVM_USERSPACE_IRQ_SOURCE_ID, irqfd->gsi, 0);
> + mutex_unlock(&kvm->lock);

This will do weird stuff (deliver the irq twice) if the irq is
MSI/MSI-X. I know this was discussed already and is a temporary
shortcut, but maybe add a comment that we really want kvm_toggle_irq,
so that we won't forget?

> +}
> +

--
MST


\
 
 \ /
  Last update: 2009-04-30 15:11    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site