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Re: [Qemu-devel] [RFC] Memory API
From: |
Alex Williamson |
Subject: |
Re: [Qemu-devel] [RFC] Memory API |
Date: |
Wed, 18 May 2011 14:02:22 -0600 |
On Wed, 2011-05-18 at 14:34 -0500, Anthony Liguori wrote:
> On 05/18/2011 02:27 PM, Jan Kiszka wrote:
> > On 2011-05-18 21:10, Anthony Liguori wrote:
> >> On 05/18/2011 10:30 AM, Jan Kiszka wrote:
> >> You really don't need to register 90% of the time. In the case of a PC
> >> with i440fx, it's really quite simple:
> >>
> >> if an I/O is to the APIC page,
> >> it's handled by the APIC
> >
> > That's not that simple. We need to tell apart:
> > - if a cpu issued the request, and which one => forward to APIC
>
> Right, but what I'm saying is that this logic lives in
> kvm-all.c:kvm_run():case EXIT_MMIO.
>
> Obviously for TCG, it's a bit more complicated but this should be
> handled way before there's any kind of general dispatch.
>
> > - if the range was addressed by a device (PCI or other system bus
> > devices) => forward to MSI or other MMIO handlers
>
> The same is true for MSI. Other MMIO handlers can be handled as
> appropriate. For instance, once an I/O is sent to the PCI bus, you can
> walk each PCI device's BAR list to figure out which device owns the I/O
> event.
>
> For ISA, it's a little trickier since ISA doesn't do positive decoding.
> You need each ISA device to declare what I/O addresses it handles.
Do we only need to handle CPU based I/O with this API? I would think we
would be layering memory regions and implementing them as a hierarchy
that reflects the actual hardware layout we're emulating. An access
from an I/O device may get a different translation to memory than a CPU
(IOMMU). We also might have a system with two VGA devices that both
register 0xa0000 with a switch in the chipset that decides which one
sees the accesses, just as real hardware does. ISTR a presentation at
one of the first KVM forums from you that talked about this type of
model. Thanks,
Alex
- [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Peter Maydell, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API,
Alex Williamson <=
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Alex Williamson, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/18
- Re: [Qemu-devel] [RFC] Memory API, Gleb Natapov, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Jan Kiszka, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Anthony Liguori, 2011/05/19
- Re: [Qemu-devel] [RFC] Memory API, Avi Kivity, 2011/05/19