Re: [PATCH 09/10] KVM: nVMX: Synchronize VMCS12 content with the shadow vmcs

[Gleb Natapov <gleb@redhat.com>]

On Thu, Apr 18, 2013 at 10:07:36AM +0300, Abel Gordon wrote:
> 
> 
> Gleb Natapov <gleb@redhat.com> wrote on 18/04/2013 09:41:16 AM:
> 
> 
> > On Wed, Apr 17, 2013 at 08:09:40PM +0300, Abel Gordon wrote:
> > > Synchronize between the VMCS12 software controlled structure and the
> > > processor-specific shadow vmcs
> > >
> > > Signed-off-by: Abel Gordon <abelg@il.ibm.com>
> > > ---
> > >  arch/x86/kvm/vmx.c |   32 ++++++++++++++++++++++++++++++++
> > >  1 file changed, 32 insertions(+)
> > >
> > > --- .before/arch/x86/kvm/vmx.c   2013-04-17 19:58:33.000000000 +0300
> > > +++ .after/arch/x86/kvm/vmx.c   2013-04-17 19:58:33.000000000 +0300
> > > @@ -356,6 +356,11 @@ struct nested_vmx {
> > >     struct page *current_vmcs12_page;
> > >     struct vmcs12 *current_vmcs12;
> > >     struct vmcs *current_shadow_vmcs;
> > > +   /*
> > > +    * Indicates if the shadow vmcs must be updated with the
> > > +    * data hold by vmcs12
> > > +    */
> > > +   bool sync_shadow_vmcs;
> > >
> > >     /* vmcs02_list cache of VMCSs recently used to run L2 guests */
> > >     struct list_head vmcs02_pool;
> > > @@ -5596,6 +5601,14 @@ static int nested_vmx_check_permission(s
> > >
> > >  static inline void nested_release_vmcs12(struct vcpu_vmx *vmx)
> > >  {
> > > +   if (enable_shadow_vmcs) {
> > > +      if (vmx->nested.current_vmcs12 != NULL) {
> > > +         /* copy to memory all shadowed fields in case
> > > +            they were modified */
> > > +         copy_shadow_to_vmcs12(vmx);
> > > +         vmx->nested.sync_shadow_vmcs = false;
> > > +      }
> > > +   }
> > >     kunmap(vmx->nested.current_vmcs12_page);
> > >     nested_release_page(vmx->nested.current_vmcs12_page);
> > >  }
> > > @@ -5724,6 +5737,10 @@ static void nested_vmx_failValid(struct
> > >               X86_EFLAGS_SF | X86_EFLAGS_OF))
> > >           | X86_EFLAGS_ZF);
> > >     get_vmcs12(vcpu)->vm_instruction_error = vm_instruction_error;
> > > +   /*
> > > +    * We don't need to force a shadow sync because
> > > +    * VM_INSTRUCTION_ERROR is not shadowed
> > > +    */
> > >  }
> > >
> > >  /* Emulate the VMCLEAR instruction */
> > > @@ -6122,6 +6139,9 @@ static int handle_vmptrld(struct kvm_vcp
> > >        vmx->nested.current_vmptr = vmptr;
> > >        vmx->nested.current_vmcs12 = new_vmcs12;
> > >        vmx->nested.current_vmcs12_page = page;
> > > +      if (enable_shadow_vmcs) {
> > > +         vmx->nested.sync_shadow_vmcs = true;
> > > +      }
> > No need braces around one statement according to kernel coding style.
> 
> The last patch introduces code within the braces... I usually prefer
> to add them in advance so you don't see the "if" statement as modified
> in future patches. If this is not a common practice, I'll remove the
> braces here and add them again later. Please confirm.
Ah, I haven't noticed that the later patch adds code here. In this case
the braces a welcome.

--
			Gleb.