Commit cdafece4 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

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: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-19-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent c91d4497

arch/x86/kvm/x86.c

+4 −1
Original line number Diff line number Diff line
@@ -10006,7 +10006,10 @@ 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);

		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)