On Fri, Jan 30, 2026 at 7:26 AM Yosry Ahmed <[email protected]> wrote:
>
> On Thu, Jan 29, 2026 at 03:28:08PM -0800, Jim Mattson wrote:
> > Add amd_pmu_refresh_host_guest_eventsel_hw() to recalculate eventsel_hw for
> > all PMCs based on the current vCPU state. This is needed because Host-Only
> > and Guest-Only counters must be enabled/disabled at:
> >
> > - SVME changes: When EFER.SVME is modified, counters with Guest-Only bits
> > need their hardware enable state updated.
> >
> > - Nested transitions: When entering or leaving guest mode, Host-Only
> > counters should be disabled/enabled and Guest-Only counters should be
> > enabled/disabled accordingly.
> >
> > Introduce svm_enter_guest_mode() and svm_leave_guest_mode() wrappers that
> > call enter_guest_mode()/leave_guest_mode() followed by the PMU refresh,
> > ensuring the PMU state stays synchronized with guest mode transitions.
> >
> > Signed-off-by: Jim Mattson <[email protected]>
> > ---
> > arch/x86/kvm/svm/nested.c | 6 +++---
> > arch/x86/kvm/svm/pmu.c | 12 ++++++++++++
> > arch/x86/kvm/svm/svm.c | 2 ++
> > arch/x86/kvm/svm/svm.h | 17 +++++++++++++++++
> > 4 files changed, 34 insertions(+), 3 deletions(-)
> >
> > diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c
> > index de90b104a0dd..a7d1901f256b 100644
> > --- a/arch/x86/kvm/svm/nested.c
> > +++ b/arch/x86/kvm/svm/nested.c
> > @@ -757,7 +757,7 @@ static void nested_vmcb02_prepare_control(struct
> > vcpu_svm *svm,
> > nested_svm_transition_tlb_flush(vcpu);
> >
> > /* Enter Guest-Mode */
> > - enter_guest_mode(vcpu);
> > + svm_enter_guest_mode(vcpu);
>
> FWIW, I think this name is a bit confusing because we also have
> enter_svm_guest_mode(). So we end up with:
>
> enter_svm_guest_mode() -> nested_vmcb02_prepare_control() ->
> svm_enter_guest_mode() -> enter_guest_mode()
>
> I actually have another proposed change [1] that moves
> enter_guest_mode() directly into enter_svm_guest_mode(), so the sequence
> would end up being:
>
> enter_svm_guest_mode() -> svm_enter_guest_mode() -> enter_guest_mode()
Yes, that is confusing. What if I renamed the existing function to
something like svm_nested_switch_to_vmcb02()?
Alternatively, I could go back to introducing a new PMU_OP, call it
from {enter,leave}_guest_mode(), and drop the wrappers.
> [1]
> https://lore.kernel.org/kvm/[email protected]/
