From mboxrd@z Thu Jan  1 00:00:00 1970
From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v12 for-xen-4.5 09/20] x86/VPMU: Add public
 xenpmu.h
Date: Mon, 29 Sep 2014 11:48:05 -0400
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To: Jan Beulich <JBeulich@suse.com>
Cc: kevin.tian@intel.com, keir@xen.org, suravee.suthikulpanit@amd.com, andrew.cooper3@citrix.com, tim@xen.org, dietmar.hahn@ts.fujitsu.com, xen-devel@lists.xen.org, Aravind.Gopalakrishnan@amd.com, jun.nakajima@intel.com, dgdegra@tycho.nsa.gov
List-Id: xen-devel@lists.xenproject.org

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