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SubjectRe: [PATCH 01/10] KVM: nVMX: Move reflection check into nested_vmx_reflect_vmexit()
On Fri, Mar 13, 2020 at 01:12:33PM +0100, Vitaly Kuznetsov wrote:
> Sean Christopherson <sean.j.christopherson@intel.com> writes:
>
> > Move the call to nested_vmx_exit_reflected() from vmx_handle_exit() into
> > nested_vmx_reflect_vmexit() and change the semantics of the return value
> > for nested_vmx_reflect_vmexit() to indicate whether or not the exit was
> > reflected into L1. nested_vmx_exit_reflected() and
> > nested_vmx_reflect_vmexit() are intrinsically tied together, calling one
> > without simultaneously calling the other makes little sense.
> >
> > No functional change intended.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> > arch/x86/kvm/vmx/nested.h | 16 +++++++++++-----
> > arch/x86/kvm/vmx/vmx.c | 4 ++--
> > 2 files changed, 13 insertions(+), 7 deletions(-)
> >
> > diff --git a/arch/x86/kvm/vmx/nested.h b/arch/x86/kvm/vmx/nested.h
> > index 21d36652f213..6bc379cf4755 100644
> > --- a/arch/x86/kvm/vmx/nested.h
> > +++ b/arch/x86/kvm/vmx/nested.h
> > @@ -72,12 +72,16 @@ static inline bool nested_ept_ad_enabled(struct kvm_vcpu *vcpu)
> > }
> >
> > /*
> > - * Reflect a VM Exit into L1.
> > + * Conditionally reflect a VM-Exit into L1. Returns %true if the VM-Exit was
> > + * reflected into L1.
> > */
> > -static inline int nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu,
> > - u32 exit_reason)
> > +static inline bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu,
> > + u32 exit_reason)
> > {
> > - u32 exit_intr_info = vmcs_read32(VM_EXIT_INTR_INFO);
> > + u32 exit_intr_info;
> > +
> > + if (!nested_vmx_exit_reflected(vcpu, exit_reason))
> > + return false;
>
> (unrelated to your patch)
>
> It's probably just me but 'nested_vmx_exit_reflected()' name always
> makes me thinkg 'the vmexit WAS [already] reflected' and not 'the vmexit
> NEEDS to be reflected'. 'nested_vmx_exit_needs_reflecting()' maybe?

Not just you. It'd be nice if the name some how reflected (ha) that the
logic is mostly based on whether or not L1 expects the exit, with a few
exceptions. E.g. something like

if (!l1_expects_vmexit(...) && !is_system_vmexit(...))
return false;

The downside of that is the logic is split, which is probably a net loss?

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