Re: [PATCH v12 for-xen-4.5 09/20] x86/VPMU: Add public xenpmu.h

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 09/29/2014 11:41 AM, Jan Beulich wrote:
>>>> On 29.09.14 at 17:19, <boris.ostrovsky@oracle.com> wrote:
>> On 09/29/2014 10:30 AM, Jan Beulich wrote:
>>>>>> On 29.09.14 at 16:17, <JBeulich@suse.com> wrote:
>>>>>>> On 25.09.14 at 21:28, <boris.ostrovsky@oracle.com> wrote:
>>>>> --- a/xen/include/public/arch-x86/xen-x86_64.h
>>>>> +++ b/xen/include/public/arch-x86/xen-x86_64.h
>>>>> @@ -174,6 +174,14 @@ struct cpu_user_regs {
>>>>>    typedef struct cpu_user_regs cpu_user_regs_t;
>>>>>    DEFINE_XEN_GUEST_HANDLE(cpu_user_regs_t);
>>>>>    
>>>>> +struct xen_pmu_regs {
>>>>> +    __DECL_REG(ip);
>>>>> +    __DECL_REG(sp);
>>>> Do you really need __DECL_REG() here? I.e. can't these two fields
>>>> be just xen_ulong_t e[is]p and the structure definition then be
>>>> shared with 32-bit code (and hence moved altogether into pmu.h)?
>>> Otoh - is cs useful at all on 64-bit?
>> perf uses user_mode() to figure which mode we are in and that requires CS.
> But that won't be complete without also looking at EFLAGS.VM.
>

True. In perf case, they explicitly state that v8086 mode is ruled out 
so EFLAGS check can be bypassed. But for completeness I should put 
EFLAGS in.

-boris