Re: [PATCH 1/2] drm/xe: Add debugfs to dump GuC's hwconfig

["Souza, Jose" <jose.souza@intel.com>]

On Fri, 2024-08-16 at 02:18 +0000, Matthew Brost wrote:
> On Thu, Aug 15, 2024 at 02:38:37PM -0700, Matt Roper wrote:
> > On Thu, Aug 15, 2024 at 08:08:45PM +0000, Matthew Brost wrote:
> > > On Thu, Aug 15, 2024 at 10:26:03AM -0700, Matt Roper wrote:
> > > > Although the query uapi is the official way to get at the GuC's hwconfig
> > > > table contents, it's still useful to have a quick debugfs interface to
> > > > dump the table in a human-readable format while debugging the driver.
> > > > 
> > > 
> > > Patch itself makes sense. Question though, would this be useful to
> > > include devcoredump? If so we should code this with the snap semantics
> > > for decoredump. See guc_exec_queue_print() for an example of this.
> > 
> > You mean include the contents of the hwconfig within the devcoredump
> > report?  I don't really have a feel for whether anyone would find that
> 
> Yes, exactly - include hwconfig within the devcoredump report.

For current platforms I don't see a reason to add it to devcoredump but maybe for future platforms...

But sounds good to have in debugfs.

> 
> Don't want to hold up the patch as I said it LGTM but just something to
> consider and if Jose (or someone on the KMD) indicates this could be
> useful it is easy enough to change to use snap semantics and wire into
> devcoredump too.
> 
> Matt
> 
> > useful or not.  My personal use case is just being able to sit down at
> > an unfamiliar machine and 'cat' the debugfs to see what the hwconfig
> > characteristics of the GPU are before I start doing experiments.
> > 
> > +Cc Jose for a UMD perspective on whether or not it would also be useful
> > to capture the hwconfig contents in the devcoredump for userspace
> > debugging.
> > 
> > 
> > Matt
> > 
> > > 
> > > Matt 
> > > 
> > > > Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
> > > > ---
> > > >  drivers/gpu/drm/xe/xe_gt_debugfs.c   | 11 ++++++
> > > >  drivers/gpu/drm/xe/xe_guc_hwconfig.c | 57 ++++++++++++++++++++++++++++
> > > >  drivers/gpu/drm/xe/xe_guc_hwconfig.h |  2 +
> > > >  3 files changed, 70 insertions(+)
> > > > 
> > > > diff --git a/drivers/gpu/drm/xe/xe_gt_debugfs.c b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> > > > index 5125d76ccfac..8f95d3a5949b 100644
> > > > --- a/drivers/gpu/drm/xe/xe_gt_debugfs.c
> > > > +++ b/drivers/gpu/drm/xe/xe_gt_debugfs.c
> > > > @@ -19,6 +19,7 @@
> > > >  #include "xe_gt_sriov_vf_debugfs.h"
> > > >  #include "xe_gt_stats.h"
> > > >  #include "xe_gt_topology.h"
> > > > +#include "xe_guc_hwconfig.h"
> > > >  #include "xe_hw_engine.h"
> > > >  #include "xe_lrc.h"
> > > >  #include "xe_macros.h"
> > > > @@ -270,6 +271,15 @@ static int vecs_default_lrc(struct xe_gt *gt, struct drm_printer *p)
> > > >  	return 0;
> > > >  }
> > > >  
> > > > +static int hwconfig(struct xe_gt *gt, struct drm_printer *p)
> > > > +{
> > > > +	xe_pm_runtime_get(gt_to_xe(gt));
> > > > +	xe_guc_hwconfig_dump(&gt->uc.guc, p);
> > > > +	xe_pm_runtime_put(gt_to_xe(gt));
> > > > +
> > > > +	return 0;
> > > > +}
> > > > +
> > > >  static const struct drm_info_list debugfs_list[] = {
> > > >  	{"hw_engines", .show = xe_gt_debugfs_simple_show, .data = hw_engines},
> > > >  	{"force_reset", .show = xe_gt_debugfs_simple_show, .data = force_reset},
> > > > @@ -288,6 +298,7 @@ static const struct drm_info_list debugfs_list[] = {
> > > >  	{"default_lrc_vcs", .show = xe_gt_debugfs_simple_show, .data = vcs_default_lrc},
> > > >  	{"default_lrc_vecs", .show = xe_gt_debugfs_simple_show, .data = vecs_default_lrc},
> > > >  	{"stats", .show = xe_gt_debugfs_simple_show, .data = xe_gt_stats_print_info},
> > > > +	{"hwconfig", .show = xe_gt_debugfs_simple_show, .data = hwconfig},
> > > >  };
> > > >  
> > > >  void xe_gt_debugfs_register(struct xe_gt *gt)
> > > > diff --git a/drivers/gpu/drm/xe/xe_guc_hwconfig.c b/drivers/gpu/drm/xe/xe_guc_hwconfig.c
> > > > index d9b570a154a2..025bad701556 100644
> > > > --- a/drivers/gpu/drm/xe/xe_guc_hwconfig.c
> > > > +++ b/drivers/gpu/drm/xe/xe_guc_hwconfig.c
> > > > @@ -6,6 +6,7 @@
> > > >  #include "xe_guc_hwconfig.h"
> > > >  
> > > >  #include <drm/drm_managed.h>
> > > > +#include <drm/drm_print.h>
> > > >  
> > > >  #include "abi/guc_actions_abi.h"
> > > >  #include "xe_bo.h"
> > > > @@ -103,3 +104,59 @@ void xe_guc_hwconfig_copy(struct xe_guc *guc, void *dst)
> > > >  	xe_map_memcpy_from(xe, dst, &guc->hwconfig.bo->vmap, 0,
> > > >  			   guc->hwconfig.size);
> > > >  }
> > > > +
> > > > +void xe_guc_hwconfig_dump(struct xe_guc *guc, struct drm_printer *p)
> > > > +{
> > > > +	size_t size = xe_guc_hwconfig_size(guc);
> > > > +	u32 *hwconfig;
> > > > +	u64 num_dw;
> > > > +	u32 extra_bytes;
> > > > +	int i = 0;
> > > > +
> > > > +	if (size == 0) {
> > > > +		drm_printf(p, "No hwconfig available\n");
> > > > +		return;
> > > > +	}
> > > > +
> > > > +	num_dw = div_u64_rem(size, sizeof(u32), &extra_bytes);
> > > > +
> > > > +	hwconfig = kzalloc(size, GFP_KERNEL);
> > > > +	if (!hwconfig) {
> > > > +		drm_printf(p, "Error: could not allocate hwconfig memory\n");
> > > > +		return;
> > > > +	}
> > > > +
> > > > +	xe_guc_hwconfig_copy(guc, hwconfig);
> > > > +
> > > > +	/* An entry requires at least three dwords for key, length, value */
> > > > +	while (i + 3 <= num_dw) {
> > > > +		u32 attribute = hwconfig[i++];
> > > > +		u32 len_dw = hwconfig[i++];
> > > > +
> > > > +		if (i + len_dw > num_dw) {
> > > > +			drm_printf(p, "Error: Attribute %u is %u dwords, but only %llu remain\n",
> > > > +				   attribute, len_dw, num_dw - i);
> > > > +			len_dw = num_dw - i;
> > > > +		}
> > > > +
> > > > +		/*
> > > > +		 * If it's a single dword (as most hwconfig attributes are),
> > > > +		 * then it's probably a number that makes sense to display
> > > > +		 * in decimal form.  In the rare cases where it's more than
> > > > +		 * one dword, just print it in hex form and let the user
> > > > +		 * figure out how to interpret it.
> > > > +		 */
> > > > +		if (len_dw == 1)
> > > > +			drm_printf(p, "[%2u] = %u\n", attribute, hwconfig[i]);
> > > > +		else
> > > > +			drm_printf(p, "[%2u] = { %*ph }\n", attribute,
> > > > +				   (int)(len_dw * sizeof(u32)), &hwconfig[i]);
> > > > +		i += len_dw;
> > > > +	}
> > > > +
> > > > +	if (i < num_dw || extra_bytes)
> > > > +		drm_printf(p, "Error: %llu extra bytes at end of hwconfig\n",
> > > > +			   (num_dw - i) * sizeof(u32) + extra_bytes);
> > > > +
> > > > +	kfree(hwconfig);
> > > > +}
> > > > diff --git a/drivers/gpu/drm/xe/xe_guc_hwconfig.h b/drivers/gpu/drm/xe/xe_guc_hwconfig.h
> > > > index b5794d641900..7df315900e1c 100644
> > > > --- a/drivers/gpu/drm/xe/xe_guc_hwconfig.h
> > > > +++ b/drivers/gpu/drm/xe/xe_guc_hwconfig.h
> > > > @@ -8,10 +8,12 @@
> > > >  
> > > >  #include <linux/types.h>
> > > >  
> > > > +struct drm_printer;
> > > >  struct xe_guc;
> > > >  
> > > >  int xe_guc_hwconfig_init(struct xe_guc *guc);
> > > >  u32 xe_guc_hwconfig_size(struct xe_guc *guc);
> > > >  void xe_guc_hwconfig_copy(struct xe_guc *guc, void *dst);
> > > > +void xe_guc_hwconfig_dump(struct xe_guc *guc, struct drm_printer *p);
> > > >  
> > > >  #endif
> > > > -- 
> > > > 2.45.2
> > > > 
> > 
> > -- 
> > Matt Roper
> > Graphics Software Engineer
> > Linux GPU Platform Enablement
> > Intel Corporation