Commit cdd6ad3a authored by Christian Borntraeger's avatar Christian Borntraeger
Browse files

KVM: polling: add architecture backend to disable polling 



There are cases where halt polling is unwanted. For example when running
KVM on an over committed LPAR we rather want to give back the CPU to
neighbour LPARs instead of polling. Let us provide a callback that
allows architectures to disable polling.

Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
parent 8ec2fa52

include/linux/kvm_host.h

+10 −0
Original line number Diff line number Diff line
@@ -1305,6 +1305,16 @@ static inline bool vcpu_valid_wakeup(struct kvm_vcpu *vcpu) 
}

#endif /* CONFIG_HAVE_KVM_INVALID_WAKEUPS */



#ifdef CONFIG_HAVE_KVM_NO_POLL

/* Callback that tells if we must not poll */

bool kvm_arch_no_poll(struct kvm_vcpu *vcpu);

#else

static inline bool kvm_arch_no_poll(struct kvm_vcpu *vcpu)

{

	return false;

}

#endif /* CONFIG_HAVE_KVM_NO_POLL */



#ifdef CONFIG_HAVE_KVM_VCPU_ASYNC_IOCTL

long kvm_arch_vcpu_async_ioctl(struct file *filp,

			       unsigned int ioctl, unsigned long arg);

virt/kvm/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -57,3 +57,6 @@ config HAVE_KVM_VCPU_ASYNC_IOCTL 


config HAVE_KVM_VCPU_RUN_PID_CHANGE

       bool



config HAVE_KVM_NO_POLL

       bool

virt/kvm/kvm_main.c

+1 −1
Original line number Diff line number Diff line
@@ -2253,7 +2253,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu) 
	u64 block_ns;



	start = cur = ktime_get();

	if (vcpu->halt_poll_ns) {

	if (vcpu->halt_poll_ns && !kvm_arch_no_poll(vcpu)) {

		ktime_t stop = ktime_add_ns(ktime_get(), vcpu->halt_poll_ns);



		++vcpu->stat.halt_attempted_poll;

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