On Sat, 2022-04-23 at 02:14 +0000, Sean Christopherson wrote:
> Trace exceptions that are re-injected, not just those that KVM is
> injecting for the first time. Debugging re-injection bugs is painful
> enough as is, not having visibility into what KVM is doing only makes
> things worse.
>
> Delay propagating pending=>injected in the non-reinjection path so that
> the tracing can properly identify reinjected exceptions.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> ---
> arch/x86/kvm/trace.h | 12 ++++++++----
> arch/x86/kvm/x86.c | 16 +++++++++-------
> 2 files changed, 17 insertions(+), 11 deletions(-)
>
> diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> index de4762517569..d07428e660e3 100644
> --- a/arch/x86/kvm/trace.h
> +++ b/arch/x86/kvm/trace.h
> @@ -358,25 +358,29 @@ TRACE_EVENT(kvm_inj_virq,
> * Tracepoint for kvm interrupt injection:
> */
> TRACE_EVENT(kvm_inj_exception,
> - TP_PROTO(unsigned exception, bool has_error, unsigned error_code),
> - TP_ARGS(exception, has_error, error_code),
> + TP_PROTO(unsigned exception, bool has_error, unsigned error_code,
> + bool reinjected),
> + TP_ARGS(exception, has_error, error_code, reinjected),
>
> TP_STRUCT__entry(
> __field( u8, exception )
> __field( u8, has_error )
> __field( u32, error_code )
> + __field( bool, reinjected )
> ),
>
> TP_fast_assign(
> __entry->exception = exception;
> __entry->has_error = has_error;
> __entry->error_code = error_code;
> + __entry->reinjected = reinjected;
> ),
>
> - TP_printk("%s (0x%x)",
> + TP_printk("%s (0x%x)%s",
> __print_symbolic(__entry->exception, kvm_trace_sym_exc),
> /* FIXME: don't print error_code if not present */
> - __entry->has_error ? __entry->error_code : 0)
> + __entry->has_error ? __entry->error_code : 0,
> + __entry->reinjected ? " [reinjected]" : "")
> );
>
> /*
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 951d0a78ccda..c3ee8dc00d3a 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -9393,6 +9393,11 @@ int kvm_check_nested_events(struct kvm_vcpu *vcpu)
>
> static void kvm_inject_exception(struct kvm_vcpu *vcpu)
> {
> + trace_kvm_inj_exception(vcpu->arch.exception.nr,
> + vcpu->arch.exception.has_error_code,
> + vcpu->arch.exception.error_code,
> + vcpu->arch.exception.injected);
> +
> if (vcpu->arch.exception.error_code && !is_protmode(vcpu))
> vcpu->arch.exception.error_code = false;
> static_call(kvm_x86_queue_exception)(vcpu);
> @@ -9450,13 +9455,6 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
>
> /* try to inject new event if pending */
> if (vcpu->arch.exception.pending) {
> - trace_kvm_inj_exception(vcpu->arch.exception.nr,
> - vcpu->arch.exception.has_error_code,
> - vcpu->arch.exception.error_code);
> -
> - vcpu->arch.exception.pending = false;
> - vcpu->arch.exception.injected = true;
> -
> if (exception_type(vcpu->arch.exception.nr) == EXCPT_FAULT)
> __kvm_set_rflags(vcpu, kvm_get_rflags(vcpu) |
> X86_EFLAGS_RF);
> @@ -9470,6 +9468,10 @@ static int inject_pending_event(struct kvm_vcpu *vcpu, bool *req_immediate_exit)
> }
>
> kvm_inject_exception(vcpu);
> +
> + vcpu->arch.exception.pending = false;
> + vcpu->arch.exception.injected = true;
> +
> can_inject = false;
> }
>
Reviewed-by: Maxim Levitsky <mlevitsk@xxxxxxxxxx>
Best regards,
Maxim Levitsky
