Re: [PATCH] util/qemu-error: prepend guest name to error message to identify affected VM owner

[Paolo Bonzini]

On 26/06/20 22:19, Mario Smarduch wrote:
> This is followup patch to the one submitted back in Oct, 19
> 
> https://lists.gnu.org/archive/html/qemu-devel/2019-10/msg02102.html
> 
> My mistake here, I took my eyes of the mailing list after I got the
> initial thumbs up. This patch follows up on Markus comments in the
> above link.
> 
> Purpose of this patch:
> 
> We want to print guest name for errors, warnings and info messages. This 
> was the first of two patches the second being MCE errors targeting a VM 
> with guest name prepended. But in a large fleet we see many other
> errors that disable a VM or crash it. In a large fleet and centralized
> logging having the guest name enables identify of owner and customer.
> 
> Signed-off-by: Mario Smarduch <msmarduch@digitalocean.com>
> ---
> Test verification summary:
> 
> a) qemu-system-x86_64 -msg help
>   guest-name=<bool (on/off)> - Prepends guest name for error messages but 
> only if -name <guestname> is set otherwise option is ignored
> 
>   timestamp=<bool (on/off)>
> 
> b) qemu-system-x86_64 -help
> -msg [timestamp[=on|off]][,guest-name=[on|off]]
>                 control error message format
>                 timestamp=on enables timestamps (default: off)
>                 guest-name=on enables guest name prefix but only if
>                               -name guest option is set (default: off)
> 
> c) man qemu
>        -msg [timestamp[=on|off]][,guest-name[=on|off]]
>               Control error message format.
> 
>               timestamp=on|off
>                      Prefix messages with a timestamp. Default is off.
> 
>               guest-name=on|off
>                      Prefix  messages  with guest name but only if -name guest
>                      option is set otherwise the option is ignored. Default is
>                      off.
> d) command options
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp
> 2020-06-26T01:01:23.140294Z qemu-system-x86_64: Testing ERROR...
> 
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp,guest-name
> 2020-06-26T01:02:30.301431Z qemu-system-x86_64: Testing ERROR...
> 
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp,guest-name \
>                                     -name guest=DROPLET-123
> 2020-06-26T01:04:37.720380Z DROPLET-1234 qemu-system-x86_64: Testing ERROR...
> 
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp=off,guest-name=off \
>                                     -name guest=DROPLET-123
> qemu-system-x86_64: Testing ERROR...
> 
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp=on,guest-name=off \
>                                     -name guest=DROPLET-123
> 2020-06-26T01:06:33.888859Z qemu-system-x86_64: Testing ERROR...
> 
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp=off,guest-name=on \
>                                     -name guest=DROPLET-123
> DROPLET-1234 qemu-system-x86_64: Testing ERROR...
> 
> ./x86_64-softmmu/qemu-system-x86_64 -msg timestamp=on,guest-name=on \
>                                     -name guest=DROPLET-123
> 2020-06-26T01:09:31.116283Z DROPLET-1234 qemu-system-x86_64: Testing ERROR... 
> 
> 
>  include/qemu/error-report.h |  2 ++
>  qemu-options.hx             | 12 +++++++++---
>  softmmu/vl.c                |  9 +++++++++
>  util/qemu-error.c           |  7 +++++++
>  4 files changed, 27 insertions(+), 3 deletions(-)
> 
> diff --git a/include/qemu/error-report.h b/include/qemu/error-report.h
> index 87532d8596..a5ad95ff1b 100644
> --- a/include/qemu/error-report.h
> +++ b/include/qemu/error-report.h
> @@ -75,5 +75,7 @@ void error_init(const char *argv0);
>  const char *error_get_progname(void);
>  
>  extern bool error_with_timestamp;
> +extern bool error_with_guestname;
> +extern const char *error_guest_name;
>  
>  #endif
> diff --git a/qemu-options.hx b/qemu-options.hx
> index 93bde2bbc8..ff75510b7c 100644
> --- a/qemu-options.hx
> +++ b/qemu-options.hx
> @@ -4290,16 +4290,22 @@ HXCOMM Deprecated by -accel tcg
>  DEF("no-kvm", 0, QEMU_OPTION_no_kvm, "", QEMU_ARCH_I386)
>  
>  DEF("msg", HAS_ARG, QEMU_OPTION_msg,
> -    "-msg timestamp[=on|off]\n"
> +    "-msg [timestamp[=on|off]][,guest-name=[on|off]]\n"
>      "                control error message format\n"
> -    "                timestamp=on enables timestamps (default: off)\n",
> +    "                timestamp=on enables timestamps (default: off)\n"
> +    "                guest-name=on enables guest name prefix but only if\n"
> +    "                              -name guest option is set (default: 
> off)\n",
>      QEMU_ARCH_ALL)
>  SRST
> -``-msg timestamp[=on|off]``
> +``-msg [timestamp[=on|off]][,guest-name[=on|off]]``
>      Control error message format.
>  
>      ``timestamp=on|off``
>          Prefix messages with a timestamp. Default is off.
> +
> +    ``guest-name=on|off``
> +        Prefix messages with guest name but only if -name guest option is set
> +        otherwise the option is ignored. Default is off.
>  ERST
>  
>  DEF("dump-vmstate", HAS_ARG, QEMU_OPTION_dump_vmstate,
> diff --git a/softmmu/vl.c b/softmmu/vl.c
> index f669c06ede..3f7aad89c3 100644
> --- a/softmmu/vl.c
> +++ b/softmmu/vl.c
> @@ -389,6 +389,12 @@ static QemuOptsList qemu_msg_opts = {
>              .name = "timestamp",
>              .type = QEMU_OPT_BOOL,
>          },
> +        {
> +            .name = "guest-name",
> +            .type = QEMU_OPT_BOOL,
> +            .help = "Prepends guest name for error messages but only if "
> +                    "-name guest is set otherwise option is ignored\n",
> +        },
>          { /* end of list */ }
>      },
>  };
> @@ -1109,6 +1115,7 @@ static void realtime_init(void)
>  static void configure_msg(QemuOpts *opts)
>  {
>      error_with_timestamp = qemu_opt_get_bool(opts, "timestamp", false);
> +    error_with_guestname = qemu_opt_get_bool(opts, "guest-name", false);
>  }
>  
>  
> @@ -3578,6 +3585,8 @@ void qemu_init(int argc, char **argv, char **envp)
>                  if (!opts) {
>                      exit(1);
>                  }
> +                /* Capture guest name if -msg guest-name is used later */
> +                error_guest_name = qemu_opt_get(opts, "guest");
>                  break;
>              case QEMU_OPTION_prom_env:
>                  if (nb_prom_envs >= MAX_PROM_ENVS) {
> diff --git a/util/qemu-error.c b/util/qemu-error.c
> index dac7c7dc50..017288b6c9 100644
> --- a/util/qemu-error.c
> +++ b/util/qemu-error.c
> @@ -26,6 +26,8 @@ typedef enum {
>  
>  /* Prepend timestamp to messages */
>  bool error_with_timestamp;
> +bool error_with_guestname;
> +const char *error_guest_name;
>  
>  int error_printf(const char *fmt, ...)
>  {
> @@ -213,6 +215,11 @@ static void vreport(report_type type, const char *fmt, 
> va_list ap)
>          g_free(timestr);
>      }
>  
> +    /* Only prepend guest name if -msg guest-name and -name guest=... are 
> set */
> +    if (error_with_guestname && error_guest_name && !cur_mon) {
> +        error_printf("%s ", error_guest_name);
> +    }
> +
>      print_loc();
>  
>      switch (type) {
> 

Queued, thanks.

Paolo