Re: [PATCH v3 6/7] tools/libxl: add vmtrace_pt_size parameter

[Wei Liu <wl@xxxxxxx>]

On Mon, Jun 22, 2020 at 08:12:26PM +0200, Michał Leszczyński wrote:
> Allow to specify the size of per-vCPU trace buffer upon
> domain creation. This is zero by default (meaning: not enabled).
> 
> Signed-off-by: Michal Leszczynski <michal.leszczynski@xxxxxxx>
> ---
>  docs/man/xl.cfg.5.pod.in             | 10 ++++++++++
>  tools/golang/xenlight/helpers.gen.go |  2 ++
>  tools/golang/xenlight/types.gen.go   |  1 +
>  tools/libxl/libxl_create.c           |  1 +
>  tools/libxl/libxl_types.idl          |  2 ++
>  tools/xl/xl_parse.c                  |  4 ++++
>  6 files changed, 20 insertions(+)
> 
> diff --git a/docs/man/xl.cfg.5.pod.in b/docs/man/xl.cfg.5.pod.in
> index 0532739c1f..78f434b722 100644
> --- a/docs/man/xl.cfg.5.pod.in
> +++ b/docs/man/xl.cfg.5.pod.in
> @@ -278,6 +278,16 @@ memory=8096 will report significantly less memory 
> available for use
>  than a system with maxmem=8096 memory=8096 due to the memory overhead
>  of having to track the unused pages.
>  
> +=item B<vmtrace_pt_size=BYTES>
> +
> +Specifies the size of processor trace buffer that would be allocated
> +for each vCPU belonging to this domain. Disabled (i.e. B<vmtrace_pt_size=0>
> +by default. This must be set to non-zero value in order to be able to
> +use processor tracing features with this domain.
> +
> +B<NOTE>: The size value must be between 4 kB and 4 GB and it must
> +be also a power of 2.
> +

Is this restriction enforced anywhere? I don't see it in this patch.

>  =back
>  
>  =head3 Guest Virtual NUMA Configuration
> diff --git a/tools/golang/xenlight/helpers.gen.go 
> b/tools/golang/xenlight/helpers.gen.go
> index 935d3bc50a..986ebbd681 100644
> --- a/tools/golang/xenlight/helpers.gen.go
> +++ b/tools/golang/xenlight/helpers.gen.go
> @@ -1117,6 +1117,7 @@ return fmt.Errorf("invalid union key '%v'", x.Type)}
>  x.ArchArm.GicVersion = GicVersion(xc.arch_arm.gic_version)
>  x.ArchArm.Vuart = VuartType(xc.arch_arm.vuart)
>  x.Altp2M = Altp2MMode(xc.altp2m)
> +x.VmtracePtSize = int(xc.vmtrace_pt_size)
>  
>   return nil}
>  
> @@ -1592,6 +1593,7 @@ return fmt.Errorf("invalid union key '%v'", x.Type)}
>  xc.arch_arm.gic_version = C.libxl_gic_version(x.ArchArm.GicVersion)
>  xc.arch_arm.vuart = C.libxl_vuart_type(x.ArchArm.Vuart)
>  xc.altp2m = C.libxl_altp2m_mode(x.Altp2M)
> +xc.vmtrace_pt_size = C.int(x.VmtracePtSize)
>  
>   return nil
>   }
> diff --git a/tools/golang/xenlight/types.gen.go 
> b/tools/golang/xenlight/types.gen.go
> index 663c1e86b4..41ec7cdd32 100644
> --- a/tools/golang/xenlight/types.gen.go
> +++ b/tools/golang/xenlight/types.gen.go
> @@ -516,6 +516,7 @@ GicVersion GicVersion
>  Vuart VuartType
>  }
>  Altp2M Altp2MMode
> +VmtracePtSize int
>  }
>  
>  type domainBuildInfoTypeUnion interface {
> diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
> index 75862dc6ed..32204b83b0 100644
> --- a/tools/libxl/libxl_create.c
> +++ b/tools/libxl/libxl_create.c
> @@ -608,6 +608,7 @@ int libxl__domain_make(libxl__gc *gc, libxl_domain_config 
> *d_config,
>              .max_evtchn_port = b_info->event_channels,
>              .max_grant_frames = b_info->max_grant_frames,
>              .max_maptrack_frames = b_info->max_maptrack_frames,
> +            .vmtrace_pt_size = b_info->vmtrace_pt_size,
>          };
>  
>          if (info->type != LIBXL_DOMAIN_TYPE_PV) {
> diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
> index 9d3f05f399..04c1704b72 100644
> --- a/tools/libxl/libxl_types.idl
> +++ b/tools/libxl/libxl_types.idl
> @@ -645,6 +645,8 @@ libxl_domain_build_info = Struct("domain_build_info",[
>      # supported by x86 HVM and ARM support is planned.
>      ("altp2m", libxl_altp2m_mode),
>  
> +    ("vmtrace_pt_size", integer),

When you add a new field please also add a LIBXL_HAVE macro to libxl.h.

> +
>      ], dir=DIR_IN,
>         copy_deprecated_fn="libxl__domain_build_info_copy_deprecated",
>  )
> diff --git a/tools/xl/xl_parse.c b/tools/xl/xl_parse.c
> index 61b4ef7b7e..6ab98dda55 100644
> --- a/tools/xl/xl_parse.c
> +++ b/tools/xl/xl_parse.c
> @@ -1861,6 +1861,10 @@ void parse_config_data(const char *config_source,
>          }
>      }
>  
> +    if (!xlu_cfg_get_long(config, "vmtrace_pt_size", &l, 1)) {
> +        b_info->vmtrace_pt_size = l;
> +    }
> +
>      if (!xlu_cfg_get_list(config, "ioports", &ioports, &num_ioports, 0)) {
>          b_info->num_ioports = num_ioports;
>          b_info->ioports = calloc(num_ioports, sizeof(*b_info->ioports));
> -- 
> 2.20.1
> 
>