x86/resctrl: Add resctrl_arch_get_num_closid()

To initialise struct resctrl_schema's num_closid, schemata_list_create()
reaches into the architectures private structure to retrieve num_closid
from the struct rdt_hw_resource. The 'half the closids' behaviour should
be part of the filesystem parts of resctrl that are the same on any
architecture. struct resctrl_schema's num_closid should include any
correction for CDP.

Having two properties called num_closid is likely to be confusing when
they have different values.

Add a helper to read the resource's num_closid from the arch code.
This should return the number of closid that the resource supports,
regardless of whether CDP is in use. Once the CDP resources are merged,
schemata_list_create() can apply the correction itself.

Using a type with an obvious size for the arch helper means changing the
type of num_closid to u32, which matches the type already used by struct
rdtgroup.

reset_all_ctrls() does not use resctrl_arch_get_num_closid(), even
though it sets up a structure for modifying the hardware. This function
will be part of the architecture code, the maximum closid should be the
maximum value the hardware has, regardless of the way resctrl is using
it. All the uses of num_closid in core.c are naturally part of the
architecture specific code.

Signed-off-by: James Morse <james.morse@arm.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Jamie Iles <jamie@nuviainc.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lkml.kernel.org/r/20210728170637.25610-9-james.morse@arm.com

1 files changed, 5 insertions, 1 deletions

diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 59d0fa78bb69..b9d200592e54 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -180,6 +180,10 @@ struct resctrl_schema {
 	struct list_head		list;
 	enum resctrl_conf_type		conf_type;
 	struct rdt_resource		*res;
-	int				num_closid;
+	u32				num_closid;
 };
+
+/* The number of closid supported by this resource regardless of CDP */
+u32 resctrl_arch_get_num_closid(struct rdt_resource *r);
+
 #endif /* _RESCTRL_H */