On 21.03.2017 05:18, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
>
> After async pf setup successfully, there is a broadcast wakeup w/ special
> token 0xffffffff which tells vCPU that it should wake up all processes
> waiting for APFs though there is no real process waiting at the moment.
>
> The async page present tracepoint print prematurely and fails to catch the
> special token setup. This patch fixes it by moving the async page present
> tracepoint after the special token setup.
>
> Before patch:
>
> qemu-system-x86-8499 [006] ...1 5973.473292: kvm_async_pf_ready: token 0x0 gva 0x0
>
> After patch:
>
> qemu-system-x86-8499 [006] ...1 5973.473292: kvm_async_pf_ready: token 0xffffffff gva 0x0
>
Wonder if there is a reason why this is traced before any work is done.
Maybe we should keep that order (by breaking up the if-else).
> Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
> Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx>
> ---
> arch/x86/kvm/x86.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 1faf620..e27eb7f 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -8566,11 +8566,11 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
> {
> struct x86_exception fault;
>
> - trace_kvm_async_pf_ready(work->arch.token, work->gva);
> if (work->wakeup_all)
> work->arch.token = ~0; /* broadcast wakeup */
> else
> kvm_del_async_pf_gfn(vcpu, work->arch.gfn);
> + trace_kvm_async_pf_ready(work->arch.token, work->gva);
>
> if ((vcpu->arch.apf.msr_val & KVM_ASYNC_PF_ENABLED) &&
> !apf_put_user(vcpu, KVM_PV_REASON_PAGE_READY)) {
>
--
Thanks,
David
