[PATCH 0/2] KVM: VMX: Avoid RDMSRs in PI x2APIC checks

From: Sean Christopherson
Date: Fri Jan 15 2021 - 17:04:59 EST


Resurrect a patch[*] from over a year ago to avoid RDMSR in a fairly hot
path in KVM's posted interrupt support. Note, in my response to that
patch, I suggested checking x2apic_supported() as well as x2apic_mode. I
have no idea why I suggested that; unless I'm missing something,
x2apic_mode can never be set if x2apic_supported() is false.

[*] https://lkml.kernel.org/r/20190723130608.26528-1-luferry@xxxxxxx/

Sean Christopherson (2):
x86/apic: Export x2apic_mode for use by KVM in "warm" path
KVM: VMX: Use x2apic_mode to avoid RDMSR when querying PI state

arch/x86/kernel/apic/apic.c | 1 +
arch/x86/kvm/vmx/posted_intr.c | 6 +++---
2 files changed, 4 insertions(+), 3 deletions(-)

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2.30.0.284.gd98b1dd5eaa7-goog