Re: [Xen-devel] [PATCH v4 6/6] x86/HVM: report the set of enabled emulated devices through CPUID

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.01.16 at 16:51, <roger.pau@xxxxxxxxxx> wrote:
> El 22/01/16 a les 16.31, Jan Beulich ha escrit:
>>>>> On 22.01.16 at 15:59, <roger.pau@xxxxxxxxxx> wrote:
>>> If that's the plan, then I think we would also need to fixup the tables
>>> provided to Dom0 in order to match what's available, but that can be
>>> discussed later.
>> 
>> I don't see what you're getting at here: The IO-APIC information
>> should be usable as is for Dom0 (as is the case for PV).
> 
> Well, the information it's usable, but the IO-APIC is not accessible by
> Dom0, you need to use PHYSDEV ops in order to manage it. One of my aims
> would be to get rid of quite of the PHYSDEV/PIRQ ops for Dom0, and
> instead provide an emulated local and IO APICs. That would also allow us
> to make use of posted-interrupts I assume (although I certainly need to
> look more deeply into this).

Wait - you're aware that some of the IO-APIC setup in the
hypervisor requires Dom0's help? Presenting it with other than
the real ACPI tables would seem to make this impossible.

> In this case, how are we going to signal Dom0 that the local and IO
> APICs reported by ACPI are usable using the bare mental interfaces?

With the above I'm not sure the answer to this would really matter.

Jan


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