Re: [PATCH v2 06/13] KVM: x86: Refactor emulate tracepoint to explicitly take context

Sean Christopherson
2020-03-03T16:48:16Z

On Wed, Feb 26, 2020 at 06:11:25PM +0100, Vitaly Kuznetsov wrote:
> Sean Christopherson <sean.j.christopherson@intel.com> writes:
>
> > Explicitly pass the emulation context to the emulate tracepoint in
> > preparation of dynamically allocation the emulation context.
> >
> > Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
> > ---
> > arch/x86/kvm/trace.h | 22 +++++++++++-----------
> > arch/x86/kvm/x86.c | 13 ++++++++-----
> > 2 files changed, 19 insertions(+), 16 deletions(-)
> >
> > diff --git a/arch/x86/kvm/trace.h b/arch/x86/kvm/trace.h
> > index f194dd058470..5605000ca5f6 100644
> > --- a/arch/x86/kvm/trace.h
> > +++ b/arch/x86/kvm/trace.h
> > @@ -731,8 +731,9 @@ TRACE_EVENT(kvm_skinit,
> > })
> >
> > TRACE_EVENT(kvm_emulate_insn,
> > - TP_PROTO(struct kvm_vcpu *vcpu, __u8 failed),
> > - TP_ARGS(vcpu, failed),
> > + TP_PROTO(struct kvm_vcpu *vcpu, struct x86_emulate_ctxt *ctxt,
> > + __u8 failed),
> > + TP_ARGS(vcpu, ctxt, failed),
> >
> > TP_STRUCT__entry(
> > __field( __u64, rip )
> > @@ -745,13 +746,10 @@ TRACE_EVENT(kvm_emulate_insn,
> >
> > TP_fast_assign(
> > __entry->csbase = kvm_x86_ops->get_segment_base(vcpu, VCPU_SREG_CS);
>
> This seems the only usage of 'vcpu' parameter now; I checked and even
> after switching to dynamic emulation context allocation we still set
> ctxt->vcpu in alloc_emulate_ctxt(), can we get rid of 'vcpu' parameter
> here then (and use ctxt->vcpu instead)?

Hmm, ya, not sure what I was thinking here.

> > - __entry->len = vcpu->arch.emulate_ctxt.fetch.ptr
> > - - vcpu->arch.emulate_ctxt.fetch.data;
> > - __entry->rip = vcpu->arch.emulate_ctxt._eip - __entry->len;
> > - memcpy(__entry->insn,
> > - vcpu->arch.emulate_ctxt.fetch.data,
> > - 15);
> > - __entry->flags = kei_decode_mode(vcpu->arch.emulate_ctxt.mode);
> > + __entry->len = ctxt->fetch.ptr - ctxt->fetch.data;
> > + __entry->rip = ctxt->_eip - __entry->len;
> > + memcpy(__entry->insn, ctxt->fetch.data, 15);
> > + __entry->flags = kei_decode_mode(ctxt->mode);
> > __entry->failed = failed;
> > ),
> >
> > @@ -764,8 +762,10 @@ TRACE_EVENT(kvm_emulate_insn,
> > )
> > );
> >
> > -#define trace_kvm_emulate_insn_start(vcpu) trace_kvm_emulate_insn(vcpu, 0)
> > -#define trace_kvm_emulate_insn_failed(vcpu) trace_kvm_emulate_insn(vcpu, 1)
> > +#define trace_kvm_emulate_insn_start(vcpu, ctxt) \
> > + trace_kvm_emulate_insn(vcpu, ctxt, 0)
> > +#define trace_kvm_emulate_insn_failed(vcpu, ctxt) \
> > + trace_kvm_emulate_insn(vcpu, ctxt, 1)
> >
> > TRACE_EVENT(
> > vcpu_match_mmio,