Re: [Xen-devel] [PATCH v4 4/7] X86: generic MSRs save/restore

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 02.12.13 at 13:12, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
> Jan Beulich wrote:
>>>>> On 02.12.13 at 09:52, "Liu, Jinsong" <jinsong.liu@xxxxxxxxx> wrote:
>>> --- a/xen/include/public/arch-x86/hvm/save.h
>>> +++ b/xen/include/public/arch-x86/hvm/save.h
>>> @@ -592,9 +592,22 @@ struct hvm_tsc_adjust {
>>> 
>>>  DECLARE_HVM_SAVE_TYPE(TSC_ADJUST, 19, struct hvm_tsc_adjust);
>>> 
>>> +#define MSR_SAVE_LOAD_MAX 16
>> 
>> Please don't - let's keep this flexible, with dynamic sizing similar
>> to how the variable size XSAVE record is being dealt with.
>> 
> 
> Sorry, I didn't figure out how to, considering the format requirement like 
> hvm_save_entry()/ hvm_load_entry() and macro.
> 
> XSAVE itself are not variable size -- it allocate at init per max feature 
> size 
> requirement (but dynamically xsave/xrstor partial of the buffer).

And you could do the same - collect at boot time how many MSRs
you might need to save at most (paralleling
HVM_CPU_XSAVE_SIZE(xfeature_mask)), but save only as much as
is needed (paralleling HVM_CPU_XSAVE_SIZE(v->arch.xcr0_accum)).

Jan


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