On Wed, Mar 15, 2023, Yan Zhao wrote:
> On Fri, Mar 10, 2023 at 04:22:51PM -0800, Sean Christopherson wrote:
> > Disable the page-track notifier code at compile time if there are no
> > external users, i.e. if CONFIG_KVM_EXTERNAL_WRITE_TRACKING=n. KVM itself
> > now hooks emulated writes directly instead of relying on the page-track
> > mechanism.
> >
> > Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> > ---
> > arch/x86/include/asm/kvm_host.h | 2 ++
> > arch/x86/include/asm/kvm_page_track.h | 2 ++
> > arch/x86/kvm/mmu/page_track.c | 9 ++++-----
> > arch/x86/kvm/mmu/page_track.h | 29 +++++++++++++++++++++++----
> > 4 files changed, 33 insertions(+), 9 deletions(-)
> >
> > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
> > index 1a4225237564..a3423711e403 100644
> > --- a/arch/x86/include/asm/kvm_host.h
> > +++ b/arch/x86/include/asm/kvm_host.h
> > @@ -1265,7 +1265,9 @@ struct kvm_arch {
> > * create an NX huge page (without hanging the guest).
> > */
> > struct list_head possible_nx_huge_pages;
> > +#ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING
> > struct kvm_page_track_notifier_head track_notifier_head;
> > +#endif
> > /*
> > * Protects marking pages unsync during page faults, as TDP MMU page
> > * faults only take mmu_lock for read. For simplicity, the unsync
> > diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h
> > index deece45936a5..53c2adb25a07 100644
> > --- a/arch/x86/include/asm/kvm_page_track.h
> > +++ b/arch/x86/include/asm/kvm_page_track.h
> The "#ifdef CONFIG_KVM_EXTERNAL_WRITE_TRACKING" can be moved to the
> front of this file?
> All the structures are only exposed for external users now.
Huh. I've no idea why I didn't do that. IIRC, the entire reason past me wrapped
track_notifier_head in an #ifdef was to allow this change in kvm_page_track.h.
I'll do this in the next version unless I discover an edge case I'm overlooking.
Thanks yet again!
