linux-kernel - [PATCH v5 2/2] x86/resctrl: Remove arch_has_empty

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Message-ID: <166430979654.372014.615622285687642644.stgit@bmoger-ubuntu>
Date:   Tue, 27 Sep 2022 15:16:36 -0500
From:   Babu Moger <babu.moger@....com>
To:     <corbet@....net>, <reinette.chatre@...el.com>,
        <tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>
CC:     <fenghua.yu@...el.com>, <dave.hansen@...ux.intel.com>,
        <x86@...nel.org>, <hpa@...or.com>, <paulmck@...nel.org>,
        <akpm@...ux-foundation.org>, <quic_neeraju@...cinc.com>,
        <rdunlap@...radead.org>, <damien.lemoal@...nsource.wdc.com>,
        <songmuchun@...edance.com>, <peterz@...radead.org>,
        <jpoimboe@...nel.org>, <pbonzini@...hat.com>, <babu.moger@....com>,
        <chang.seok.bae@...el.com>, <pawan.kumar.gupta@...ux.intel.com>,
        <jmattson@...gle.com>, <daniel.sneddon@...ux.intel.com>,
        <sandipan.das@....com>, <tony.luck@...el.com>,
        <james.morse@....com>, <linux-doc@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <bagasdotme@...il.com>,
        <eranian@...gle.com>
Subject: [PATCH v5 2/2] 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 <reinette.chatre@...el.com>
Signed-off-by: Babu Moger <babu.moger@....com>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
---
 arch/x86/kernel/cpu/resctrl/core.c        |    2 --
 arch/x86/kernel/cpu/resctrl/ctrlmondata.c |    3 +--
 include/linux/resctrl.h                   |    6 +++---
 3 files changed, 4 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
index a5c51a14fbce..c2657754672e 100644
--- a/arch/x86/kernel/cpu/resctrl/core.c
+++ b/arch/x86/kernel/cpu/resctrl/core.c
@@ -869,7 +869,6 @@ 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) {
@@ -890,7 +889,6 @@ 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) {
diff --git a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
index 87666275eed9..7f38c8bd8429 100644
--- a/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
+++ b/arch/x86/kernel/cpu/resctrl/ctrlmondata.c
@@ -98,8 +98,7 @@ 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;
 	}
diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
index 21deb5212bbd..46ed8589857c 100644
--- a/include/linux/resctrl.h
+++ b/include/linux/resctrl.h
@@ -72,11 +72,12 @@ 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.
  */
@@ -85,7 +86,6 @@ 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;
 };