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[Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback
From: |
Michael S. Tsirkin |
Subject: |
[Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback |
Date: |
Sun, 11 Jul 2010 21:54:56 +0300 |
User-agent: |
Mutt/1.5.20 (2009-12-10) |
On Sun, Jul 11, 2010 at 09:30:59PM +0300, Avi Kivity wrote:
> On 07/11/2010 09:26 PM, Alex Williamson wrote:
> >On Sun, 2010-07-11 at 21:14 +0300, Avi Kivity wrote:
> >>On 07/11/2010 09:09 PM, Alex Williamson wrote:
> >>>For device assignment, we need to know when the VM writes an end
> >>>of interrupt to the APIC, which allows us to de-assert the interrupt
> >>>line and clear the DisINTx bit. Add a new wrapper for ioapic
> >>>generated interrupts with a callback on eoi and create an interface
> >>>for drivers to be notified on eoi.
> >>>
> >>You aren't going to get this with kvm's in-kernel irqchip, so we need a
> >>new interface there.
> >Registering an eventfd for the eoi seems like a reasonable alternative.
>
> I'm worried about that racing (with what?)
With device asserting the interrupt?
Need to make sure that all possible scenarious work well:
device asserts interrupt
driver clears interrupt
device asserts interrupt
eoi
device asserts interrupt
driver clears interrupt
eoi
device asserts interrupt
etc
Not that I see issues, these are things we need to check.
> >I also need to figure out how to avoid bouncing the vfio interrupt
> >events through qemu, but it's a functional start. Thanks,
>
> I thought the scheduler has/wants to have something that moves the
> irq to whatever thread it wakes up. With irqfd, it would flow
> naturally.
>
> --
> I have a truly marvellous patch that fixes the bug which this
> signature is too narrow to contain.
- [Qemu-devel] [RFC PATCH 2/5] Minimal RAM API support, (continued)
- [Qemu-devel] [RFC PATCH 3/5] RAM API: Make use of it for x86 PC, Alex Williamson, 2010/07/11
- [Qemu-devel] [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Alex Williamson, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Avi Kivity, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Alex Williamson, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Avi Kivity, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback,
Michael S. Tsirkin <=
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Alex Williamson, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Michael S. Tsirkin, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Alex Williamson, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Michael S. Tsirkin, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Michael S. Tsirkin, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Alex Williamson, 2010/07/11
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Avi Kivity, 2010/07/12
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Gleb Natapov, 2010/07/12
- [Qemu-devel] Re: [RFC PATCH 4/5] APIC/IOAPIC EOI callback, Avi Kivity, 2010/07/12
[Qemu-devel] [RFC PATCH 5/5] VFIO based device assignment, Alex Williamson, 2010/07/11