[PATCH v2 1/2] RISCV: KVM: add tracepoints for entry and exit events

[Anup Patel]

On Mon, Apr 15, 2024 at 8:45 AM Shenlin Liang
<liangshenlin at eswincomputing.com> wrote:
>
> Like other architectures, RISCV KVM also needs to add these event
> tracepoints to count the number of times kvm guest entry/exit.
>
> Signed-off-by: Shenlin Liang <liangshenlin at eswincomputing.com>

LGTM.

Reviewed-by: Anup Patel <anup at brainfault.org>

Regards,
Anup

> ---
>  arch/riscv/kvm/trace.h | 67 ++++++++++++++++++++++++++++++++++++++++++
>  arch/riscv/kvm/vcpu.c  |  7 +++++
>  2 files changed, 74 insertions(+)
>  create mode 100644 arch/riscv/kvm/trace.h
>
> diff --git a/arch/riscv/kvm/trace.h b/arch/riscv/kvm/trace.h
> new file mode 100644
> index 000000000000..3d54175d805c
> --- /dev/null
> +++ b/arch/riscv/kvm/trace.h
> @@ -0,0 +1,67 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Tracepoints for RISC-V KVM
> + *
> + * Copyright 2024 Beijing ESWIN Computing Technology Co., Ltd.
> + *
> + */
> +#if !defined(_TRACE_KVM_H) || defined(TRACE_HEADER_MULTI_READ)
> +#define _TRACE_KVM_H
> +
> +#include <linux/tracepoint.h>
> +
> +#undef TRACE_SYSTEM
> +#define TRACE_SYSTEM kvm
> +
> +TRACE_EVENT(kvm_entry,
> +       TP_PROTO(struct kvm_vcpu *vcpu),
> +       TP_ARGS(vcpu),
> +
> +       TP_STRUCT__entry(
> +               __field(unsigned long, pc)
> +       ),
> +
> +       TP_fast_assign(
> +               __entry->pc     = vcpu->arch.guest_context.sepc;
> +       ),
> +
> +       TP_printk("PC: 0x016%lx", __entry->pc)
> +);
> +
> +TRACE_EVENT(kvm_exit,
> +       TP_PROTO(struct kvm_cpu_trap *trap),
> +       TP_ARGS(trap),
> +
> +       TP_STRUCT__entry(
> +               __field(unsigned long, sepc)
> +               __field(unsigned long, scause)
> +               __field(unsigned long, stval)
> +               __field(unsigned long, htval)
> +               __field(unsigned long, htinst)
> +       ),
> +
> +       TP_fast_assign(
> +               __entry->sepc           = trap->sepc;
> +               __entry->scause         = trap->scause;
> +               __entry->stval          = trap->stval;
> +               __entry->htval          = trap->htval;
> +               __entry->htinst         = trap->htinst;
> +       ),
> +
> +       TP_printk("SEPC:0x%lx, SCAUSE:0x%lx, STVAL:0x%lx, HTVAL:0x%lx, HTINST:0x%lx",
> +               __entry->sepc,
> +               __entry->scause,
> +               __entry->stval,
> +               __entry->htval,
> +               __entry->htinst)
> +);
> +
> +#endif /* _TRACE_RSICV_KVM_H */
> +
> +#undef TRACE_INCLUDE_PATH
> +#define TRACE_INCLUDE_PATH .
> +#undef TRACE_INCLUDE_FILE
> +#define TRACE_INCLUDE_FILE trace
> +
> +/* This part must be outside protection */
> +#include <trace/define_trace.h>
> diff --git a/arch/riscv/kvm/vcpu.c b/arch/riscv/kvm/vcpu.c
> index b5ca9f2e98ac..f4e27004ceb8 100644
> --- a/arch/riscv/kvm/vcpu.c
> +++ b/arch/riscv/kvm/vcpu.c
> @@ -21,6 +21,9 @@
>  #include <asm/cacheflush.h>
>  #include <asm/kvm_vcpu_vector.h>
>
> +#define CREATE_TRACE_POINTS
> +#include "trace.h"
> +
>  const struct _kvm_stats_desc kvm_vcpu_stats_desc[] = {
>         KVM_GENERIC_VCPU_STATS(),
>         STATS_DESC_COUNTER(VCPU, ecall_exit_stat),
> @@ -782,6 +785,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>                  */
>                 kvm_riscv_local_tlb_sanitize(vcpu);
>
> +               trace_kvm_entry(vcpu);
> +
>                 guest_timing_enter_irqoff();
>
>                 kvm_riscv_vcpu_enter_exit(vcpu);
> @@ -820,6 +825,8 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu)
>
>                 local_irq_enable();
>
> +               trace_kvm_exit(&trap);
> +
>                 preempt_enable();
>
>                 kvm_vcpu_srcu_read_lock(vcpu);
> --
> 2.37.2
>