diff options
| author | Longpeng(Mike) | 2017-08-08 12:05:32 +0800 |
|---|---|---|
| committer | Paolo Bonzini | 2017-08-08 10:57:43 +0200 |
| commit | 199b5763d329b43c88f6ad539db8a6c6b42f8edb (patch) | |
| tree | 224f4ebeb9e58c43ea1916e63e813452f81dd45a /virt | |
| parent | 1b4d56b86a370a3785a33eba23e2e3009f5a03af (diff) | |
KVM: add spinlock optimization framework
If a vcpu exits due to request a user mode spinlock, then
the spinlock-holder may be preempted in user mode or kernel mode.
(Note that not all architectures trap spin loops in user mode,
only AMD x86 and ARM/ARM64 currently do).
But if a vcpu exits in kernel mode, then the holder must be
preempted in kernel mode, so we should choose a vcpu in kernel mode
as a more likely candidate for the lock holder.
This introduces kvm_arch_vcpu_in_kernel() to decide whether the
vcpu is in kernel-mode when it's preempted. kvm_vcpu_on_spin's
new argument says the same of the spinning VCPU.
Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/arm/arm.c | 5 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 4 |
2 files changed, 8 insertions, 1 deletions
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c index a39a1e161e63..862f820d06d4 100644 --- a/virt/kvm/arm/arm.c +++ b/virt/kvm/arm/arm.c @@ -416,6 +416,11 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v) && !v->arch.power_off && !v->arch.pause); } +bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu) +{ + return false; +} + /* Just ensure a guest exit from a particular CPU */ static void exit_vm_noop(void *info) { diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 15252d723b54..e17c40d986f3 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2317,7 +2317,7 @@ static bool kvm_vcpu_eligible_for_directed_yield(struct kvm_vcpu *vcpu) #endif } -void kvm_vcpu_on_spin(struct kvm_vcpu *me) +void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode) { struct kvm *kvm = me->kvm; struct kvm_vcpu *vcpu; @@ -2348,6 +2348,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me) continue; if (swait_active(&vcpu->wq) && !kvm_arch_vcpu_runnable(vcpu)) continue; + if (yield_to_kernel_mode && !kvm_arch_vcpu_in_kernel(vcpu)) + continue; if (!kvm_vcpu_eligible_for_directed_yield(vcpu)) continue; |