x86/resctrl: Remove data_width and the tabular format

The resctrl architecture code provides a data_width for the controls of each
resource. This is used to zero pad all control values in the schemata file so
they appear in columns. The same is done with the resource names to complete
the visual effect. e.g.

  | SMBA:0=2048
  |   L3:0=00ff

AMD platforms discover their maximum bandwidth for the MB resource from
firmware, but hard-code the data_width to 4. If the maximum bandwidth requires
more digits - the tabular format is silently broken.  This is also broken when
the mba_MBps mount option is used as the field width isn't updated. If new
schema are added resctrl will need to be able to determine the maximum width.
The benefit of this pretty-printing is questionable.

Instead of handling runtime discovery of the data_width for AMD platforms,
remove the feature. These fields are always zero padded so should be harmless
to remove if the whole field has been treated as a number.  In the above
example, this would now look like this:

  | SMBA:0=2048
  |   L3:0=ff

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Reviewed-by: Fenghua Yu <fenghuay@nvidia.com>
Reviewed-by: Babu Moger <babu.moger@amd.com>
Tested-by: Shaopeng Tan <tan.shaopeng@jp.fujitsu.com>
Tested-by: Peter Newman <peternewman@google.com>
Tested-by: Amit Singh Tomar <amitsinght@marvell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@nvidia.com> # arm64
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/r/20250311183715.16445-7-james.morse@arm.com

1 files changed, 0 insertions, 2 deletions

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 736b9a9a9464..e1a982adef45 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -214,7 +214,6 @@ enum resctrl_schema_fmt {
  * @ctrl_domains:	RCU list of all control domains for this resource
  * @mon_domains:	RCU list of all monitor domains for this resource
  * @name:		Name to use in "schemata" file.
- * @data_width:		Character width of data when displaying
  * @default_ctrl:	Specifies default cache cbm or memory B/W percent.
  * @schema_fmt:		Which format string and parser is used for this schema.
  * @evt_list:		List of monitoring events
@@ -232,7 +231,6 @@ struct rdt_resource {
 	struct list_head	ctrl_domains;
 	struct list_head	mon_domains;
 	char			*name;
-	int			data_width;
 	u32			default_ctrl;
 	enum resctrl_schema_fmt	schema_fmt;
 	struct list_head	evt_list;