On Tue, Feb 15, 2022, Chao Gao wrote:
> >--- a/arch/x86/kvm/vmx/vmx.c
> >+++ b/arch/x86/kvm/vmx/vmx.c
> >@@ -5302,9 +5302,16 @@ static int handle_apic_eoi_induced(struct kvm_vcpu *vcpu)
> > static int handle_apic_write(struct kvm_vcpu *vcpu)
> > {
> > unsigned long exit_qualification = vmx_get_exit_qual(vcpu);
> >- u32 offset = exit_qualification & 0xfff;
> >
> >- /* APIC-write VM exit is trap-like and thus no need to adjust IP */
> >+ /*
> >+ * APIC-write VM-Exit is trap-like, KVM doesn't need to advance RIP and
> >+ * hardware has done any necessary aliasing, offset adjustments, etc...
> >+ * for the access. I.e. the correct value has already been written to
> >+ * the vAPIC page for the correct 16-byte chunk. KVM needs only to
> >+ * retrieve the register value and emulate the access.
> >+ */
> >+ u32 offset = exit_qualification & 0xff0;
>
> Can we take this opportunity to remove offset/exit_qualification?
> They are used just once.
Definitely should have dropped exit_qualification, not sure why I didn't.
I'd prefer to keep offset to document what is held in vmcs.EXIT_QUALIFICATION
without having to add an explicit comment.
