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Re: [Qemu-devel] [PATCH v5 00/18] IOMMU: Enable interrupt remapping for

From: Peter Xu
Subject: Re: [Qemu-devel] [PATCH v5 00/18] IOMMU: Enable interrupt remapping for Intel IOMMU
Date: Thu, 28 Apr 2016 17:18:02 +0800
User-agent: Mutt/1.5.24 (2015-08-30)

On Thu, Apr 28, 2016 at 09:19:28AM +0200, Jan Kiszka wrote:
> On 2016-04-28 09:05, Peter Xu wrote:
> > v5 changes:
> > - patch 10: add vector checking for IOAPIC interrupts (this may help
> >   debug in the future, will only generate warning if specify
> > - patch 13: replace error_report() with a trace. [Jan]
> > - patch 14: rename parameter "intr" to "intremap", to be aligned
> >   with kernel parameter [Jan]
> > - patch 15: fix comments for vtd_iec_notify_fn
> > - patch 17 & 18 (added): fix issue when IR enabled with devices
> >   using level-triggered interrupts, like e1000. Adding it to the end
> >   of series, since this issue never happen without IR.
> > 
> >   Patch 17 adds read-only check for IOAPIC entries.
> >   Patch 18 clears remote IRR bit when entry configured as
> >   edge-triggered.
> IIUC, your series does not address irqfd yet, only by chance if the
> target is an IOAPIC pin for which you set up routes now. Correct?

Ah, yes, vhost and vfio should be in the notifier list as well. I
just missed that. :(

If not consider the IEC invalidation, the series should work for
irqfd, right?

> Instead of fiddling with irq routes for the IOAPIC - where we don't need
> it -, I would suggest to do the following: Send IOAPIC events via
> kvm_irqchip_send_msi to the kernel. Only irqfd users (vhost, vfio)
> should use the pattern you are now applying to the IOAPIC: establish
> static routes as an irqfd is set up, and that route should be translated
> by the iommu first, register an IEC notifier to update any affected
> route when the iommu translation changes.

Yes, maybe that's the right thing to do. Or say, when split irqchip,
IOAPIC can avoid using GSI routes any more. If with that, I should
also remove lots of things, like: IEC notifiers for IOAPIC, and all
things related to msi route sync-up in IOAPIC codes with KVM (so I
suppose we will save 24 gsi route entries for KVM, which sounds

(Ah... I think the series is keep growing...)


-- peterx

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