Re: [Xen-devel] [PATCH v3 1/8] x86/vmx_update_guest_cr: minor optimization

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.07.16 at 13:55, <czuzu@xxxxxxxxxxxxxxx> wrote:
> On 7/8/2016 2:48 PM, Jan Beulich wrote:
>>>>> On 08.07.16 at 13:39, <czuzu@xxxxxxxxxxxxxxx> wrote:
>>> On 7/6/2016 6:49 PM, Corneliu ZUZU wrote:
>>>> Minor optimization @ vmx_update_guest_cr: checks if
>>> v->arch.hvm_vmx.exec_control
>>>> was modified before actually calling vmx_update_cpu_exec_control(v).
>>>>
>>>> Signed-off-by: Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>
>>>> ---
>>>> Changed since v2: <nothing>
>>>> ---
>>>>    xen/arch/x86/hvm/vmx/vmx.c | 5 ++++-
>>>>    1 file changed, 4 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
>>>> index df19579..8ab074f 100644
>>>> --- a/xen/arch/x86/hvm/vmx/vmx.c
>>>> +++ b/xen/arch/x86/hvm/vmx/vmx.c
>>>> @@ -1434,8 +1434,10 @@ static void vmx_update_guest_cr(struct vcpu *v,
>>> unsigned int cr)
>>>>            if ( paging_mode_hap(v->domain) )
>>>>            {
>>>>                /* Manage GUEST_CR3 when CR0.PE=0. */
>>>> +            uint32_t old_ctls = v->arch.hvm_vmx.exec_control;
>>>>                uint32_t cr3_ctls = (CPU_BASED_CR3_LOAD_EXITING |
>>>>                                     CPU_BASED_CR3_STORE_EXITING);
>>>> +
>>>>                v->arch.hvm_vmx.exec_control &= ~cr3_ctls;
>>>>                if ( !hvm_paging_enabled(v) && !vmx_unrestricted_guest(v) )
>>>>                    v->arch.hvm_vmx.exec_control |= cr3_ctls;
>>>> @@ -1445,7 +1447,8 @@ static void vmx_update_guest_cr(struct vcpu *v,
>>> unsigned int cr)
>>>>                     monitor_ctrlreg_bitmask(VM_EVENT_X86_CR3) )
>>>>                    v->arch.hvm_vmx.exec_control |= 
>>>> CPU_BASED_CR3_LOAD_EXITING;
>>>>    
>>>> -            vmx_update_cpu_exec_control(v);
>>>> +            if ( old_ctls != v->arch.hvm_vmx.exec_control )
>>>> +                vmx_update_cpu_exec_control(v);
>>>>            }
>>>>    
>>>>            if ( !nestedhvm_vcpu_in_guestmode(v) )
>>> I'm wondering if you could ack this as well (if there's nothing wrong w/
>>> it) and push it to be done with it. :-)
>> Well, if you had pinged the patch at least once, I probably would.
>> I don't, however, recall having seen any such ping (only resends).
> 
> So is a 'ping' (haven't done that before) still necessary? Is a ping a 
> simple 'reply-to-all' including 'Ping: ' in the subject? :-)

It's not very much formalized. What I do in such a case is, as you
say, prefix the subject with Ping:, but change addressing so that
the people expected to reply end up in To:, while everyone else in
the original To: list (i.e. including xen-devel) would get moved to
Cc:.

And while, with the adjustment to addressees in my earlier reply, I
already tried to do kind of a ping to them, I think it wouldn't hurt if
you did another explicit one.

Jan


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