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

[Corneliu ZUZU <czuzu@xxxxxxxxxxxxxxx>]

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).
>
> Jan
So is a 'ping' (haven't done that before) still necessary? Is a ping a 
simple 'reply-to-all' including 'Ping: ' in the subject? :-)
Thanks,
Corneliu.

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