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

Message

Sean Christopherson Jan. 15, 2021, 10:03 p.m. UTC

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/[e-mail]/

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(-)

Comments

Paolo Bonzini Jan. 18, 2021, 6:24 p.m. UTC | #1

On 15/01/21 23:03, Sean Christopherson wrote:
> 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/[e-mail]/
> 
> 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(-)
> 

Queued, thanks.

Paolo