Gautam Menghani <[email protected]> writes:

> When debugging issues in KVM guests, it is sometimes helpful to have a
> unified trace log of both guest and host to see where things are going
> wrong. Expose the TB (timebase) offset through QEMU monitor to enable
> capturing of unified log.
>
> The below steps can be then used to get a unified log:
> 1. In host
> trace-cmd record -e kvm_hv:kvm_guest_enter -e kvm_hv:kvm_guest_exit \
>     -C ppc-tb -o trace_host.dat
>
> 2. In guest
> trace-cmd record -e powerpc:hcall_entry -e powerpc:hcall_exit -C ppc-tb \
>     --ts-offset <TB offset from QEMU monitor> -o trace_guest.dat
>
>   NOTE: The TB offset would be reported as a negative number in QEMU
>   monitor. For this step, the minus sign must be ignored.
>
> 3. Transfer the guest logs to the host with scp/rsync
>
> 4. Unify the logs
> trace-cmd report -i trace_host.dat -i trace_guest.dat > combined_log
>
> Signed-off-by: Gautam Menghani <[email protected]>
> ---
> v1 -> v2:
> 1. Remove extra deref and ref code (Vaibhav)
> 2. Fix the QEMU monitor output to add the new field at the end (Vaibhav)
Thanks Gautam from addressing V1 review comments. With this feel free to
add

Reviewed-by: Vaibhav Jain<[email protected]>

>
>  hw/ppc/ppc.c          | 5 +++++
>  target/ppc/cpu.h      | 1 +
>  target/ppc/cpu_init.c | 5 +++--
>  3 files changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index a512d4fa64..b123b4cc1c 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -515,6 +515,11 @@ uint64_t cpu_ppc_get_tb(ppc_tb_t *tb_env, uint64_t 
> vmclk, int64_t tb_offset)
>      return ns_to_tb(tb_env->tb_freq, vmclk) + tb_offset;
>  }
>  
> +int64_t cpu_ppc_load_tb_offset(CPUPPCState *env)
> +{
> +    return env->tb_env->tb_offset;
> +}
> +
>  uint64_t cpu_ppc_load_tbl (CPUPPCState *env)
>  {
>      ppc_tb_t *tb_env = env->tb_env;
> diff --git a/target/ppc/cpu.h b/target/ppc/cpu.h
> index 057c54bbb8..cbd5964b1a 100644
> --- a/target/ppc/cpu.h
> +++ b/target/ppc/cpu.h
> @@ -1693,6 +1693,7 @@ void cpu_ppc_store_hdecr(CPUPPCState *env, target_ulong 
> value);
>  void cpu_ppc_store_tbu40(CPUPPCState *env, uint64_t value);
>  uint64_t cpu_ppc_load_purr(CPUPPCState *env);
>  void cpu_ppc_store_purr(CPUPPCState *env, uint64_t value);
> +int64_t cpu_ppc_load_tb_offset(CPUPPCState *env);
>  #if !defined(CONFIG_USER_ONLY)
>  target_ulong load_40x_pit(CPUPPCState *env);
>  void store_40x_pit(CPUPPCState *env, target_ulong val);
> diff --git a/target/ppc/cpu_init.c b/target/ppc/cpu_init.c
> index a02187ce5a..8cab5e12b6 100644
> --- a/target/ppc/cpu_init.c
> +++ b/target/ppc/cpu_init.c
> @@ -7620,8 +7620,9 @@ void ppc_cpu_dump_state(CPUState *cs, FILE *f, int 
> flags)
>  #if !defined(CONFIG_USER_ONLY)
>      if (env->tb_env) {
>          qemu_fprintf(f, "TB %08" PRIu32 " %08" PRIu64
> -                     " DECR " TARGET_FMT_lu "\n", cpu_ppc_load_tbu(env),
> -                     cpu_ppc_load_tbl(env), cpu_ppc_load_decr(env));
> +                     " DECR " TARGET_FMT_lu " TB_OFFSET %016" PRId64 "\n",
> +                     cpu_ppc_load_tbu(env), cpu_ppc_load_tbl(env),
> +                     cpu_ppc_load_decr(env), cpu_ppc_load_tb_offset(env));
>      }
>  #else
>      qemu_fprintf(f, "TB %08" PRIu32 " %08" PRIu64 "\n", 
> cpu_ppc_load_tbu(env),
> -- 
> 2.54.0
>

-- 
Cheers
~ Vaibhav

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