From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH 6/7] KVM: x86: Use common definition for kvm_nested_vmexit tracepoint
Date: Tue, 21 Jul 2020 15:59:06 +0200 [thread overview]
Message-ID: <87imehotp1.fsf@vitty.brq.redhat.com> (raw)
In-Reply-To: <20200721002717.GC20375@linux.intel.com>
Sean Christopherson <sean.j.christopherson@intel.com> writes:
> On Mon, Jul 20, 2020 at 06:52:15PM +0200, Vitaly Kuznetsov wrote:
>> Sean Christopherson <sean.j.christopherson@intel.com> writes:
>> > +TRACE_EVENT_KVM_EXIT(kvm_nested_vmexit);
>> >
>> > /*
>> > * Tracepoint for #VMEXIT reinjected to the guest
>> > diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
>> > index fc70644b916ca..f437d99f4db09 100644
>> > --- a/arch/x86/kvm/vmx/nested.c
>> > +++ b/arch/x86/kvm/vmx/nested.c
>> > @@ -5912,10 +5912,7 @@ bool nested_vmx_reflect_vmexit(struct kvm_vcpu *vcpu)
>> > exit_intr_info = vmx_get_intr_info(vcpu);
>> > exit_qual = vmx_get_exit_qual(vcpu);
>> >
>> > - trace_kvm_nested_vmexit(vcpu, exit_reason, exit_qual,
>> > - vmx->idt_vectoring_info, exit_intr_info,
>> > - vmcs_read32(VM_EXIT_INTR_ERROR_CODE),
>> > - KVM_ISA_VMX);
>> > + trace_kvm_nested_vmexit(exit_reason, vcpu, KVM_ISA_VMX);
>> >
>> > /* If L0 (KVM) wants the exit, it trumps L1's desires. */
>> > if (nested_vmx_l0_wants_exit(vcpu, exit_reason))
>>
>> With so many lines removed I'm almost in love with the patch! However,
>> when testing on SVM (unrelated?) my trace log looks a bit ugly:
>>
>> <...>-315119 [010] 3733.092646: kvm_nested_vmexit: CAN'T FIND FIELD "rip"<CANT FIND FIELD exit_code>vcpu 0 reason npf rip 0x400433 info1 0x0000000200000006 info2 0x0000000000641000 intr_info 0x00000000 error_code 0x00000000
>> <...>-315119 [010] 3733.092655: kvm_nested_vmexit: CAN'T FIND FIELD "rip"<CANT FIND FIELD exit_code>vcpu 0 reason npf rip 0x400433 info1 0x0000000100000014 info2 0x0000000000400000 intr_info 0x00000000 error_code 0x00000000
>>
>> ...
>>
>> but after staring at this for some time I still don't see where this
>> comes from :-( ... but reverting this commit helps:
>
> The CAN'T FIND FIELD blurb comes from tools/lib/traceevent/event-parse.c.
>
> I assume you are using tooling of some form to generate the trace, i.e. the
> issue doesn't show up in /sys/kernel/debug/tracing/trace. If that's the
> case, this is more or less ABI breakage :-(
>
Right you are,
the tool is called 'trace-cmd record -e kvm ...' / 'trace-cmd report'
but I always thought it's not any different from looking at
/sys/kernel/debug/tracing/trace directly. Apparently I was wrong. 'cat
/sys/kernel/debug/tracing/trace' seems to be OK, e.g.:
qemu-system-x86-20263 [006] .... 75982.292657: kvm_nested_vmexit: vcpu 0 reason hypercall rip 0x40122f info1 0x0000000000000000 info2 0x0000000000000000 intr_info 0x00000000 error_code 0x00000000
--
Vitaly
next prev parent reply other threads:[~2020-07-21 13:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-18 6:38 [PATCH 0/7] KVM: x86: Tracepoint improvements and fixes Sean Christopherson
2020-07-18 6:38 ` [PATCH 1/7] KVM: x86: Add RIP to the kvm_entry, i.e. VM-Enter, tracepoint Sean Christopherson
2020-07-18 6:38 ` [PATCH 2/7] KVM: x86: Read guest RIP from within the kvm_nested_vmexit tracepoint Sean Christopherson
2020-07-18 6:38 ` [PATCH 3/7] KVM: VMX: Add a helper to test for a valid error code given an intr info Sean Christopherson
2020-07-18 6:38 ` [PATCH 4/7] KVM: x86: Add intr/vectoring info and error code to kvm_exit tracepoint Sean Christopherson
2020-07-18 6:38 ` [PATCH 5/7] KVM: x86: Add macro wrapper for defining " Sean Christopherson
2020-07-18 6:38 ` [PATCH 6/7] KVM: x86: Use common definition for kvm_nested_vmexit tracepoint Sean Christopherson
2020-07-20 16:52 ` Vitaly Kuznetsov
2020-07-21 0:27 ` Sean Christopherson
2020-07-21 13:59 ` Vitaly Kuznetsov [this message]
2020-07-21 19:31 ` Sean Christopherson
2020-07-21 21:42 ` Steven Rostedt
2020-08-12 18:10 ` Sean Christopherson
2020-07-18 6:38 ` [PATCH 7/7] KVM: nVMX: Read EXIT_QUAL and INTR_INFO only when needed for nested exit Sean Christopherson
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