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Subject[PATCH v2 18/43] KVM: x86: Invoke kvm_vcpu_block() directly for non-HALTED wait states
Call kvm_vcpu_block() directly for all wait states except HALTED so that
kvm_vcpu_halt() is no longer a misnomer on x86.

Functionally, this means KVM will never attempt halt-polling or adjust
vcpu->halt_poll_ns for INIT_RECEIVED (a.k.a. Wait-For-SIPI (WFS)) or
AP_RESET_HOLD; UNINITIALIZED is handled in kvm_arch_vcpu_ioctl_run(),
and x86 doesn't use any other "wait" states.

As mentioned above, the motivation of this is purely so that "halt" isn't
overloaded on x86, e.g. in KVM's stats. Skipping halt-polling for WFS
(and RESET_HOLD) has no meaningful effect on guest performance as there
are typically single-digit numbers of INIT-SIPI sequences per AP vCPU,
per boot, versus thousands of HLTs just to boot to console.

Reviewed-by: David Matlack <>
Signed-off-by: Sean Christopherson <>
arch/x86/kvm/x86.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index cd51f100e906..e0219acfd9cf 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9899,7 +9899,10 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)
if (!kvm_arch_vcpu_runnable(vcpu) &&
(!kvm_x86_ops.pre_block || static_call(kvm_x86_pre_block)(vcpu) == 0)) {
srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);
- kvm_vcpu_halt(vcpu);
+ if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED)
+ kvm_vcpu_halt(vcpu);
+ else
+ kvm_vcpu_block(vcpu);
vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);

if (kvm_x86_ops.post_block)
 \ /
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