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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: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Christian Borntraeger 2019-03-05 05:30:01 -05:00
parent 8ec2fa52ea
commit cdd6ad3ac6
3 changed files with 14 additions and 1 deletions
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10
include/linux/kvm_host.h
View File

@ -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);

3
virt/kvm/Kconfig
View File

@ -57,3 +57,6 @@ config HAVE_KVM_VCPU_ASYNC_IOCTL
config HAVE_KVM_VCPU_RUN_PID_CHANGE
bool
config HAVE_KVM_NO_POLL
bool

2
virt/kvm/kvm_main.c
View File

@ -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;