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

Vitaly Kuznetsov
2020-02-26T17:13:03Z

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)?

> - __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,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 79d1113ad6e7..69d3dd64d90c 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6460,10 +6460,13 @@ void kvm_inject_realmode_interrupt(struct kvm_vcpu *vcpu, int irq, int inc_eip)
> }
> EXPORT_SYMBOL_GPL(kvm_inject_realmode_interrupt);
>
> -static int handle_emulation_failure(struct kvm_vcpu *vcpu, int emulation_type)
> +static int handle_emulation_failure(struct x86_emulate_ctxt *ctxt,
> + int emulation_type)
> {
> + struct kvm_vcpu *vcpu = emul_to_vcpu(ctxt);
> +
> ++vcpu->stat.insn_emulation_fail;
> - trace_kvm_emulate_insn_failed(vcpu);
> + trace_kvm_emulate_insn_failed(vcpu, ctxt);
>
> if (emulation_type & EMULTYPE_VMWARE_GP) {
> kvm_queue_exception_e(vcpu, GP_VECTOR, 0);
> @@ -6788,7 +6791,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
>
> r = x86_decode_insn(ctxt, insn, insn_len);
>
> - trace_kvm_emulate_insn_start(vcpu);
> + trace_kvm_emulate_insn_start(vcpu, ctxt);
> ++vcpu->stat.insn_emulation;
> if (r != EMULATION_OK) {
> if ((emulation_type & EMULTYPE_TRAP_UD) ||
> @@ -6810,7 +6813,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> inject_emulated_exception(ctxt);
> return 1;
> }
> - return handle_emulation_failure(vcpu, emulation_type);
> + return handle_emulation_failure(ctxt, emulation_type);
> }
> }
>
> @@ -6856,7 +6859,7 @@ int x86_emulate_instruction(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa,
> emulation_type))
> return 1;
>
> - return handle_emulation_failure(vcpu, emulation_type);
> + return handle_emulation_failure(ctxt, emulation_type);
> }
>
> if (ctxt->have_exception) {

--
Vitaly