Commit fac42688 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: Split out a kvm_vcpu_block() helper from kvm_vcpu_halt() 



Factor out the "block" part of kvm_vcpu_halt() so that x86 can emulate
non-halt wait/sleep/block conditions that should not be subjected to
halt-polling.

No functional change intended.

Reviewed-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: default avatarDavid Matlack <dmatlack@google.com>
Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
Message-Id: <20211009021236.4122790-15-seanjc@google.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 91b99ea7

include/linux/kvm_host.h

+1 −0
Original line number Diff line number Diff line
@@ -1103,6 +1103,7 @@ void kvm_sigset_activate(struct kvm_vcpu *vcpu); 
void kvm_sigset_deactivate(struct kvm_vcpu *vcpu);



void kvm_vcpu_halt(struct kvm_vcpu *vcpu);

bool kvm_vcpu_block(struct kvm_vcpu *vcpu);

void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu);

void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu);

bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu);

virt/kvm/kvm_main.c

+36 −16
Original line number Diff line number Diff line
@@ -3272,6 +3272,35 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu) 
	return ret;

}



/*

 * Block the vCPU until the vCPU is runnable, an event arrives, or a signal is

 * pending.  This is mostly used when halting a vCPU, but may also be used

 * directly for other vCPU non-runnable states, e.g. x86's Wait-For-SIPI.

 */

bool kvm_vcpu_block(struct kvm_vcpu *vcpu)

{

	struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);

	bool waited = false;



	kvm_arch_vcpu_blocking(vcpu);



	prepare_to_rcuwait(wait);

	for (;;) {

		set_current_state(TASK_INTERRUPTIBLE);



		if (kvm_vcpu_check_block(vcpu) < 0)

			break;



		waited = true;

		schedule();

	}

	finish_rcuwait(wait);



	kvm_arch_vcpu_unblocking(vcpu);



	return waited;

}



static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start,

					  ktime_t end, bool success)

{
@@ -3294,9 +3323,14 @@ static inline void update_halt_poll_stats(struct kvm_vcpu *vcpu, ktime_t start, 
	}

}



/*

 * Emulate a vCPU halt condition, e.g. HLT on x86, WFI on arm, etc...  If halt

 * polling is enabled, busy wait for a short time before blocking to avoid the

 * expensive block+unblock sequence if a wake event arrives soon after the vCPU

 * is halted.

 */

void kvm_vcpu_halt(struct kvm_vcpu *vcpu)

{

	struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);

	bool halt_poll_allowed = !kvm_arch_no_poll(vcpu);

	bool do_halt_poll = halt_poll_allowed && vcpu->halt_poll_ns;

	ktime_t start, cur, poll_end;
@@ -3319,21 +3353,7 @@ void kvm_vcpu_halt(struct kvm_vcpu *vcpu) 
		} while (kvm_vcpu_can_poll(cur, stop));

	}



	kvm_arch_vcpu_blocking(vcpu);



	prepare_to_rcuwait(wait);

	for (;;) {

		set_current_state(TASK_INTERRUPTIBLE);



		if (kvm_vcpu_check_block(vcpu) < 0)

			break;



		waited = true;

		schedule();

	}

	finish_rcuwait(wait);



	kvm_arch_vcpu_unblocking(vcpu);

	waited = kvm_vcpu_block(vcpu);



	cur = ktime_get();

	if (waited) {