Re: [PATCH 7/8] KVM: x86: Trace re-injected exceptions

From: Sean Christopherson <seanjc@google.com>
To: Maxim Levitsky <mlevitsk@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	"Maciej S . Szmigiero" <maciej.szmigiero@oracle.com>
Subject: Re: [PATCH 7/8] KVM: x86: Trace re-injected exceptions
Date: Mon, 4 Apr 2022 16:14:54 +0000	[thread overview]
Message-ID: <YksZfqZr4SyEUk6H@google.com> (raw)
In-Reply-To: <df8e53474fb161f83c8cb8b9816995b23798545b.camel@redhat.com>

On Mon, Apr 04, 2022, Maxim Levitsky wrote:
> On Sat, 2022-04-02 at 01:09 +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.
> > 
> > Signed-off-by: Sean Christopherson <seanjc@google.com>
> > ---
> >  arch/x86/kvm/x86.c | 8 ++++----
> >  1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> > index 7a066cf92692..384091600bc2 100644
> > --- a/arch/x86/kvm/x86.c
> > +++ b/arch/x86/kvm/x86.c
> > @@ -9382,6 +9382,10 @@ 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);
> > +
> 
> Can we use a {new tracepoint / new parameter for this tracepoint} for this to
> avoid confusion?

Good idea, a param to capture re-injection would be very helpful.