x86/resctrl: Remove arch_has_empty_bitmaps

The field arch_has_empty_bitmaps is not required anymore. The field
min_cbm_bits is enough to validate the CBM (capacity bit mask) if the
architecture can support the zero CBM or not.

Suggested-by: Reinette Chatre <[email protected]>
Signed-off-by: Babu Moger <[email protected]>
Signed-off-by: Borislav Petkov <[email protected]>
Reviewed-by: Reinette Chatre <[email protected]>
Reviewed-by: Fenghua Yu <[email protected]>
Link: https://lore.kernel.org/r/166430979654.372014.615622285687642644.stgit@bmoger-ubuntu

Author: babumoger

arch/x86/kernel/cpu/resctrl/core.c

@@ -828,7 +828,6 @@ static __init void rdt_init_res_defs_intel(void)
 		if (r->rid == RDT_RESOURCE_L3 ||
 		    r->rid == RDT_RESOURCE_L2) {
 			r->cache.arch_has_sparse_bitmaps = false;
-			r->cache.arch_has_empty_bitmaps = false;
 			r->cache.arch_has_per_cpu_cfg = false;
 			r->cache.min_cbm_bits = 1;
 		} else if (r->rid == RDT_RESOURCE_MBA) {
@@ -849,7 +848,6 @@ static __init void rdt_init_res_defs_amd(void)
 		if (r->rid == RDT_RESOURCE_L3 ||
 		    r->rid == RDT_RESOURCE_L2) {
 			r->cache.arch_has_sparse_bitmaps = true;
-			r->cache.arch_has_empty_bitmaps = true;
 			r->cache.arch_has_per_cpu_cfg = true;
 			r->cache.min_cbm_bits = 0;
 		} else if (r->rid == RDT_RESOURCE_MBA) {

arch/x86/kernel/cpu/resctrl/ctrlmondata.c

@@ -105,8 +105,7 @@ static bool cbm_validate(char *buf, u32 *data, struct rdt_resource *r)
 		return false;
 	}
 
-	if ((!r->cache.arch_has_empty_bitmaps && val == 0) ||
-	    val > r->default_ctrl) {
+	if ((r->cache.min_cbm_bits > 0 && val == 0) || val > r->default_ctrl) {
 		rdt_last_cmd_puts("Mask out of range\n");
 		return false;
 	}

include/linux/resctrl.h

@@ -89,11 +89,12 @@ struct rdt_domain {
 /**
  * struct resctrl_cache - Cache allocation related data
  * @cbm_len:		Length of the cache bit mask
- * @min_cbm_bits:	Minimum number of consecutive bits to be set
+ * @min_cbm_bits:	Minimum number of consecutive bits to be set.
+ *			The value 0 means the architecture can support
+ *			zero CBM.
  * @shareable_bits:	Bitmask of shareable resource with other
  *			executing entities
  * @arch_has_sparse_bitmaps:	True if a bitmap like f00f is valid.
- * @arch_has_empty_bitmaps:	True if the '0' bitmap is valid.
  * @arch_has_per_cpu_cfg:	True if QOS_CFG register for this cache
  *				level has CPU scope.
  */
@@ -102,7 +103,6 @@ struct resctrl_cache {
 	unsigned int	min_cbm_bits;
 	unsigned int	shareable_bits;
 	bool		arch_has_sparse_bitmaps;
-	bool		arch_has_empty_bitmaps;
 	bool		arch_has_per_cpu_cfg;
 };