Re: [Xen-devel] [PATCH v8 01/21] xen/x86: add bitmap of enabled emulated devices

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 16.11.15 at 19:33, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 16/11/15 12:18, Jan Beulich wrote:
>>>>> On 06.11.15 at 17:05, <roger.pau@xxxxxxxxxx> wrote:
>>> --- a/xen/include/public/arch-x86/xen.h
>>> +++ b/xen/include/public/arch-x86/xen.h
>>> @@ -265,7 +265,31 @@ typedef struct arch_shared_info arch_shared_info_t;
>>>   * XEN_DOMCTL_INTERFACE_VERSION.
>>>   */
>>>  struct xen_arch_domainconfig {
>>> -    char dummy;
>>> +#define _XEN_X86_EMU_LAPIC          0
>>> +#define XEN_X86_EMU_LAPIC           (1U<<_XEN_X86_EMU_LAPIC)
>>> +#define _XEN_X86_EMU_HPET           1
>>> +#define XEN_X86_EMU_HPET            (1U<<_XEN_X86_EMU_HPET)
>>> +#define _XEN_X86_EMU_PM             2
>>> +#define XEN_X86_EMU_PM              (1U<<_XEN_X86_EMU_PM)
>>> +#define _XEN_X86_EMU_RTC            3
>>> +#define XEN_X86_EMU_RTC             (1U<<_XEN_X86_EMU_RTC)
>>> +#define _XEN_X86_EMU_IOAPIC         4
>>> +#define XEN_X86_EMU_IOAPIC          (1U<<_XEN_X86_EMU_IOAPIC)
>>> +#define _XEN_X86_EMU_PIC            5
>>> +#define XEN_X86_EMU_PIC             (1U<<_XEN_X86_EMU_PIC)
>>> +#define _XEN_X86_EMU_VGA            6
>>> +#define XEN_X86_EMU_VGA             (1U<<_XEN_X86_EMU_VGA)
>>> +#define _XEN_X86_EMU_IOMMU          7
>>> +#define XEN_X86_EMU_IOMMU           (1U<<_XEN_X86_EMU_IOMMU)
>>> +#define _XEN_X86_EMU_PIT            8
>>> +#define XEN_X86_EMU_PIT             (1U<<_XEN_X86_EMU_PIT)
>> While only used for a domctl (so far), I still think we should aim at
>> making this a complete set (i.e. preempt future additions to the
>> set if at all possible). I say this because - having looked again - I'm
>> missing things like MTRR, PAT, and 8254 here.
> 
> Use (or not) of MTRR and PAT should be controlled exclusively via the
> guests cpuid policy.  Unlike the above bits, they are architectural
> components of the CPU itself, rather than external devices on the
> motherboard.

For MTRR - yes, agreed. But what CPUID bit do I not recall that allows
identifying PAT availability?

Jan


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