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| author | Longpeng(Mike) <longpeng2@huawei.com> | 2017-08-08 06:05:32 +0200 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2017-08-08 10:57:43 +0200 |
| commit | 199b5763d329b43c88f6ad539db8a6c6b42f8edb (patch) | |
| tree | 224f4ebeb9e58c43ea1916e63e813452f81dd45a /virt/kvm/kvm_main.c | |
| parent | KVM: x86: use general helpers for some cpuid manipulation (diff) | |
| download | linux-199b5763d329b43c88f6ad539db8a6c6b42f8edb.tar.xz linux-199b5763d329b43c88f6ad539db8a6c6b42f8edb.zip | |
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/kvm/kvm_main.c')
| -rw-r--r-- | virt/kvm/kvm_main.c | 4 |
1 files changed, 3 insertions, 1 deletions
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; |