Commit 98c25ead authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: VMX: Move preemption timer <=> hrtimer dance to common x86 



Handle the switch to/from the hypervisor/software timer when a vCPU is
blocking in common x86 instead of in VMX.  Even though VMX is the only
user of a hypervisor timer, the logic and all functions involved are
generic x86 (unless future CPUs do something completely different and
implement a hypervisor timer that runs regardless of mode).

Handling the switch in common x86 will allow for the elimination of the
pre/post_blocks hooks, and also lets KVM switch back to the hypervisor
timer if and only if it was in use (without additional params).  Add a
comment explaining why the switch cannot be deferred to kvm_sched_out()
or kvm_vcpu_block().

Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Reviewed-by: default avatarMaxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20211208015236.1616697-8-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 12a8eee5

arch/x86/kvm/vmx/vmx.c

+1 −5
Original line number Diff line number Diff line
@@ -7568,16 +7568,12 @@ void vmx_update_cpu_dirty_logging(struct kvm_vcpu *vcpu) 


static int vmx_pre_block(struct kvm_vcpu *vcpu)

{

	if (kvm_lapic_hv_timer_in_use(vcpu))

		kvm_lapic_switch_to_sw_timer(vcpu);



	return 0;

}



static void vmx_post_block(struct kvm_vcpu *vcpu)

{

	if (kvm_x86_ops.set_hv_timer)

		kvm_lapic_switch_to_hv_timer(vcpu);



}



static void vmx_setup_mce(struct kvm_vcpu *vcpu)

arch/x86/kvm/x86.c

+21 −0
Original line number Diff line number Diff line
@@ -10146,8 +10146,21 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) 


static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu)

{

	bool hv_timer;



	if (!kvm_arch_vcpu_runnable(vcpu) &&

	    (!kvm_x86_ops.pre_block || static_call(kvm_x86_pre_block)(vcpu) == 0)) {

		/*

		 * Switch to the software timer before halt-polling/blocking as

		 * the guest's timer may be a break event for the vCPU, and the

		 * hypervisor timer runs only when the CPU is in guest mode.

		 * Switch before halt-polling so that KVM recognizes an expired

		 * timer before blocking.

		 */

		hv_timer = kvm_lapic_hv_timer_in_use(vcpu);

		if (hv_timer)

			kvm_lapic_switch_to_sw_timer(vcpu);



		srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx);

		if (vcpu->arch.mp_state == KVM_MP_STATE_HALTED)

			kvm_vcpu_halt(vcpu);
@@ -10155,6 +10168,9 @@ static inline int vcpu_block(struct kvm *kvm, struct kvm_vcpu *vcpu) 
			kvm_vcpu_block(vcpu);

		vcpu->srcu_idx = srcu_read_lock(&kvm->srcu);



		if (hv_timer)

			kvm_lapic_switch_to_hv_timer(vcpu);



		if (kvm_x86_ops.post_block)

			static_call(kvm_x86_post_block)(vcpu);
@@ -10349,6 +10365,11 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu) 
			r = -EINTR;

			goto out;

		}

		/*

		 * It should be impossible for the hypervisor timer to be in

		 * use before KVM has ever run the vCPU.

		 */

		WARN_ON_ONCE(kvm_lapic_hv_timer_in_use(vcpu));

		kvm_vcpu_block(vcpu);

		if (kvm_apic_accept_events(vcpu) < 0) {

			r = 0;