February 25, 2025 at 11:49 AM, "Sean Christopherson" <seanjc@xxxxxxxxxx> wrote: > > On Wed, Feb 19, 2025, Yosry Ahmed wrote: > > > > Instead of using X86_FEATURE_USE_IBPB to guard the IBPB execution in the > > vCPU load path, introduce a static branch, similar to switch_mm_*_ibpb. > > > > This makes it obvious in spectre_v2_user_select_mitigation() what > > exactly is being toggled, instead of the unclear X86_FEATURE_USE_IBPB > > (which will be shortly removed). It also provides more fine-grained > > control, making it simpler to change/add paths that control the IBPB in > > the vCPU load path without affecting other IBPBs. > > > > Signed-off-by: Yosry Ahmed <yosry.ahmed@xxxxxxxxx> > > > > --- > > > > arch/x86/include/asm/nospec-branch.h | 2 ++ > > arch/x86/kernel/cpu/bugs.c | 5 +++++ > > arch/x86/kvm/svm/svm.c | 2 +- > > arch/x86/kvm/vmx/vmx.c | 2 +- > > 4 files changed, 9 insertions(+), 2 deletions(-) > > > > diff --git a/arch/x86/include/asm/nospec-branch.h b/arch/x86/include/asm/nospec-branch.h > > index 7cbb76a2434b9..a22836c5fb338 100644 > > --- a/arch/x86/include/asm/nospec-branch.h > > +++ b/arch/x86/include/asm/nospec-branch.h > > @@ -552,6 +552,8 @@ DECLARE_STATIC_KEY_FALSE(switch_to_cond_stibp); > > DECLARE_STATIC_KEY_FALSE(switch_mm_cond_ibpb); > > DECLARE_STATIC_KEY_FALSE(switch_mm_always_ibpb); > > +DECLARE_STATIC_KEY_FALSE(vcpu_load_ibpb); > > > > How about ibpb_on_vcpu_load? To make it easy for readers to understand exactly > what the knob controls. I was trying to remain consistent with the existing static branches' names, but I am fine with ibpb_on_vcpu_load if others don't object.
