[PATCH v2 4/7] KVM: avoid unnecessary wait for a async pf

Xiao Guangrong
2010-11-01T08:57:08Z

In current code, it checks async pf completion out of the wait context,
like this:

if (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE &&
!vcpu->arch.apf.halted)
r = vcpu_enter_guest(vcpu);
else {
......
kvm_vcpu_block(vcpu)
^- waiting until 'async_pf.done' is not empty
}

kvm_check_async_pf_completion(vcpu)
^- delete list from async_pf.done

So, if we check aysnc pf completion first, it can be blocked at
kvm_vcpu_block

Fixed by mark the vcpu is unhalted in kvm_check_async_pf_completion()
path

Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
---
arch/x86/kvm/x86.c | 1 +
1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9b543f4..4da8485 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6280,6 +6280,7 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
vcpu->arch.fault.address = work->arch.token;
kvm_inject_page_fault(vcpu);
}
+ vcpu->arch.apf.halted = false;
}

bool kvm_arch_can_inject_async_page_present(struct kvm_vcpu *vcpu)
--
1.7.0.4