[PATCH 2/2] KVM: VMX: Use x2apic_mode to avoid RDMSR when querying PI state

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


Use x2apic_mode instead of x2apic_enabled() when adjusting the
destination ID during Posted Interrupt updates. This avoids the costly
RDMSR that is hidden behind x2apic_enabled().

Reported-by: luferry <luferry@xxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/x86/kvm/vmx/posted_intr.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
index f02962dcc72c..4831bc44ce66 100644
--- a/arch/x86/kvm/vmx/posted_intr.c
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -54,7 +54,7 @@ void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)

dest = cpu_physical_id(cpu);

- if (x2apic_enabled())
+ if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
@@ -104,7 +104,7 @@ static void __pi_post_block(struct kvm_vcpu *vcpu)

dest = cpu_physical_id(vcpu->cpu);

- if (x2apic_enabled())
+ if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
@@ -174,7 +174,7 @@ int pi_pre_block(struct kvm_vcpu *vcpu)
*/
dest = cpu_physical_id(vcpu->pre_pcpu);

- if (x2apic_enabled())
+ if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
--
2.30.0.284.gd98b1dd5eaa7-goog