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Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for em
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC |
Date: |
Wed, 13 Apr 2016 11:33:04 +0800 |
User-agent: |
Mutt/1.5.24 (2015-08-30) |
On Tue, Apr 12, 2016 at 08:39:02AM -0700, Jan Kiszka wrote:
> On 2016-04-12 02:02, Peter Xu wrote:
[...]
> > Yes, I should consider other x86 platforms like AMD. Thanks to point
> > out. It seems that there are many places in the patchset that lacks
> > thorough consideration about this. Will try to fix them in next
> > version.
> >
> > Regarding to the above MSI solution: I'd say it is a good way to
> > hide everything else behind. However, since we introduced one extra
> > layer (MSI) which actually does not exist, not sure there would be
> > problem too. Also, I feel it a little bit hacky if we "create" one
> > MSI out of the air... For example, if someone tries to capture MSIs
> > from QEMU inside in the APIC memory writes, he will see something he
> > cannot explain if he never knows this hack's there. Considering the
> > above, I would prefer hooks, or better to provide a callback (a
> > function pointer that others like AMD can override) to do the
> > translation. How do you think?
>
> The HPET does send MSIs, and I'm not sure how much different the
> IOAPIC's message actually is. In any case, modelling it as MSI is
> neither adding incorrectness nor making the code more complex (in fact,
> the contrary is true!). Last but not least, it would be trivial to
> filter out non-PCI MSI sources if we wanted to trace only PCI - because
> we need to identify the origin anyway for remapping purposes. So,
> explicit hooking looks like the wrong way to me.
I am just not sure about the difference between IOAPIC's messages
and MSI ones. For now, they seems very alike. However, I am not sure
whether it would be not alike in the future. E.g., if one day, we
extend APIC bus to support more than 255 CPUs (could it? I do not
know for sure), here if we are with this "MSI layer", we would not
be able to do that, since MSI only support 8 bits for destination ID
field. That's my only worry now. If you (or Radim? or anyone more
experienced on this than me) can confirm that this would never be a
problem, I'd be glad to take the MSI way.
Thanks.
-- peterx
- [Qemu-devel] [PATCH v2 06/13] intel_iommu: define interrupt remap table addr register, (continued)
- [Qemu-devel] [PATCH v2 06/13] intel_iommu: define interrupt remap table addr register, Peter Xu, 2016/04/11
- [Qemu-devel] [PATCH v2 07/13] intel_iommu: handle interrupt remap enable, Peter Xu, 2016/04/11
- [Qemu-devel] [PATCH v2 08/13] intel_iommu: define several structs for IOMMU IR, Peter Xu, 2016/04/11
- [Qemu-devel] [PATCH v2 09/13] intel_iommu: provide helper function vtd_get_iommu, Peter Xu, 2016/04/11
- [Qemu-devel] [PATCH v2 10/13] ioapic-common: add iommu for IOAPICCommonState, Peter Xu, 2016/04/11
- [Qemu-devel] [PATCH v2 11/13] intel_iommu: add IR translation faults defines, Peter Xu, 2016/04/11
- [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Peter Xu, 2016/04/11
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Jan Kiszka, 2016/04/12
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Peter Xu, 2016/04/12
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Jan Kiszka, 2016/04/12
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC,
Peter Xu <=
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Jan Kiszka, 2016/04/12
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Peter Xu, 2016/04/13
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Peter Xu, 2016/04/13
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Jan Kiszka, 2016/04/13
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Peter Xu, 2016/04/13
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Jan Kiszka, 2016/04/14
- Re: [Qemu-devel] [PATCH v2 12/13] intel_iommu: ioapic: IR support for emulated IOAPIC, Peter Xu, 2016/04/14
[Qemu-devel] [PATCH v2 13/13] intel_iommu: Add support for PCI MSI remap, Peter Xu, 2016/04/11