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

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Date:   Fri, 15 Jan 2021 14:03:52 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, luferry <luferry@....com>
Subject: [PATCH 0/2] KVM: VMX: Avoid RDMSRs in PI x2APIC checks

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@163.com/

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(-)

-- 
2.30.0.284.gd98b1dd5eaa7-goog