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Date: Tue, 2 Apr 2024 17:23:39 -0400
From: "Michael S. Tsirkin" <mst@redhat.com>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: linux-kernel@vger.kernel.org, Adrian Hunter <adrian.hunter@intel.com>,
	Ian Rogers <irogers@google.com>, Jiri Olsa <jolsa@kernel.org>,
	Kan Liang <kan.liang@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Zhu Lingshan <lingshan.zhu@intel.com>
Subject: Re: [PATCH fyi 1/1] perf trace beauty: Sync linux/vhost.h with the
 kernel sources
Message-ID: <20240402172151-mutt-send-email-mst@kernel.org>
References: <ZfybkuM8DKsdX_yO@x1>
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On Thu, Mar 21, 2024 at 05:41:54PM -0300, Arnaldo Carvalho de Melo wrote:
> tldr; Just FYI, I'm carrying this on the perf tools tree.
> 
> Full explanation:
> 
> There used to be no copies, with tools/ code using kernel headers
> directly. From time to time tools/perf/ broke due to legitimate kernel
> hacking. At some point Linus complained about such direct usage. Then we
> adopted the current model.
> 
> The way these headers are used in perf are not restricted to just
> including them to compile something.
> 
> There are sometimes used in scripts that convert defines into string
> tables, etc, so some change may break one of these scripts, or new MSRs
> may use some different #define pattern, etc.
> 
> E.g.:
> 
>   $ ls -1 tools/perf/trace/beauty/*.sh | head -5
>   tools/perf/trace/beauty/arch_errno_names.sh
>   tools/perf/trace/beauty/drm_ioctl.sh
>   tools/perf/trace/beauty/fadvise.sh
>   tools/perf/trace/beauty/fsconfig.sh
>   tools/perf/trace/beauty/fsmount.sh
>   $
>   $ tools/perf/trace/beauty/fadvise.sh
>   static const char *fadvise_advices[] = {
>         [0] = "NORMAL",
>         [1] = "RANDOM",
>         [2] = "SEQUENTIAL",
>         [3] = "WILLNEED",
>         [4] = "DONTNEED",
>         [5] = "NOREUSE",
>   };
>   $
> 
> The tools/perf/check-headers.sh script, part of the tools/ build
> process, points out changes in the original files.
> 
> So its important not to touch the copies in tools/ when doing changes in
> the original kernel headers, that will be done later, when
> check-headers.sh inform about the change to the perf tools hackers.
> 
> To get the changes in:
> 
>   1496c47065f9f841 ("vhost-vdpa: uapi to support reporting per vq size")
> 
> To pick up these changes and support them:
> 
>   $ tools/perf/trace/beauty/vhost_virtio_ioctl.sh > before
>   $ cp include/uapi/linux/vhost.h tools/perf/trace/beauty/include/uapi/linux/vhost.h
>   $ tools/perf/trace/beauty/vhost_virtio_ioctl.sh > after
>   $ diff -u before after
>   --- before	2024-03-21 17:33:58.878173388 -0300
>   +++ after	2024-03-21 17:34:07.687563333 -0300
>   @@ -49,6 +49,7 @@
>    	[0x7B] = "VDPA_GET_VRING_GROUP",
>    	[0x7F] = "VDPA_GET_VRING_DESC_GROUP",
>    	[0x80] = "VDPA_GET_VQS_COUNT",
>   +	[0x80] = "VDPA_GET_VRING_SIZE",
>    	[0x81] = "VDPA_GET_GROUP_NUM",
>    	[0x8] = "NEW_WORKER",
>    };
>   $
> 
> For instance, see how those 'cmd' ioctl arguments get translated, now
> VDPA_GET_VRING_SIZE will be as well.
> 
>   # perf trace -a -e ioctl --max-events=10
>        0.000 ( 0.011 ms): pipewire/2261 ioctl(fd: 60, cmd: SNDRV_PCM_HWSYNC, arg: 0x1)                   = 0
>       21.353 ( 0.014 ms): pipewire/2261 ioctl(fd: 60, cmd: SNDRV_PCM_HWSYNC, arg: 0x1)                   = 0
>       25.766 ( 0.014 ms): gnome-shell/2196 ioctl(fd: 14, cmd: DRM_I915_IRQ_WAIT, arg: 0x7ffe4a22c740)    = 0
>       25.845 ( 0.034 ms): gnome-shel:cs0/2212 ioctl(fd: 14, cmd: DRM_I915_IRQ_EMIT, arg: 0x7fd43915dc70) = 0
>       25.916 ( 0.011 ms): gnome-shell/2196 ioctl(fd: 9, cmd: DRM_MODE_ADDFB2, arg: 0x7ffe4a22c8a0)       = 0
>       25.941 ( 0.025 ms): gnome-shell/2196 ioctl(fd: 9, cmd: DRM_MODE_ATOMIC, arg: 0x7ffe4a22c840)       = 0
>       32.915 ( 0.009 ms): gnome-shell/2196 ioctl(fd: 9, cmd: DRM_MODE_RMFB, arg: 0x7ffe4a22cf9c)         = 0
>       42.522 ( 0.013 ms): gnome-shell/2196 ioctl(fd: 14, cmd: DRM_I915_IRQ_WAIT, arg: 0x7ffe4a22c740)    = 0
>       42.579 ( 0.031 ms): gnome-shel:cs0/2212 ioctl(fd: 14, cmd: DRM_I915_IRQ_EMIT, arg: 0x7fd43915dc70) = 0
>       42.644 ( 0.010 ms): gnome-shell/2196 ioctl(fd: 9, cmd: DRM_MODE_ADDFB2, arg: 0x7ffe4a22c8a0)       = 0
>   #
> 
> Cc: Adrian Hunter <adrian.hunter@intel.com>
> Cc: Ian Rogers <irogers@google.com>
> Cc: Jiri Olsa <jolsa@kernel.org>
> Cc: Kan Liang <kan.liang@linux.intel.com>
> Cc: Michael S. Tsirkin <mst@redhat.com>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: Zhu Lingshan <lingshan.zhu@intel.com>
> Link: https://lore.kernel.org/lkml/
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>


Thanks a lot for taking care of this! So given the header is actually
buggy pls hang on to this change until I merge the fix for the header
(you were CC'd on the patch).
It's great we have this redundancy which allowed us to catch the bug
in time, and many thanks to Namhyung Kim for reporting the issue!


> ---
>  tools/perf/trace/beauty/include/uapi/linux/vhost.h | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/tools/perf/trace/beauty/include/uapi/linux/vhost.h b/tools/perf/trace/beauty/include/uapi/linux/vhost.h
> index 649560c685f13b73..bea6973906134656 100644
> --- a/tools/perf/trace/beauty/include/uapi/linux/vhost.h
> +++ b/tools/perf/trace/beauty/include/uapi/linux/vhost.h
> @@ -227,4 +227,11 @@
>   */
>  #define VHOST_VDPA_GET_VRING_DESC_GROUP	_IOWR(VHOST_VIRTIO, 0x7F,	\
>  					      struct vhost_vring_state)
> +
> +/* Get the queue size of a specific virtqueue.
> + * userspace set the vring index in vhost_vring_state.index
> + * kernel set the queue size in vhost_vring_state.num
> + */
> +#define VHOST_VDPA_GET_VRING_SIZE	_IOWR(VHOST_VIRTIO, 0x80,	\
> +					      struct vhost_vring_state)
>  #endif
> -- 
> 2.44.0