linux-kernel - [tip: x86/cache] x86/resctrl: Handle throttle

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Message-ID: <174180001862.14745.5960718022865281710.tip-bot2@tip-bot2>
Date: Wed, 12 Mar 2025 17:20:18 -0000
From: "tip-bot2 for James Morse" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: James Morse <james.morse@....com>, "Borislav Petkov (AMD)" <bp@...en8.de>,
 Reinette Chatre <reinette.chatre@...el.com>, Fenghua Yu <fenghuay@...dia.com>,
 Babu Moger <babu.moger@....com>, Shaopeng Tan <tan.shaopeng@...fujitsu.com>,
 Peter Newman <peternewman@...gle.com>,
 Amit Singh Tomar <amitsinght@...vell.com>,
 Shanker Donthineni <sdonthineni@...dia.com>, x86@...nel.org,
 linux-kernel@...r.kernel.org
Subject: [tip: x86/cache] x86/resctrl: Handle throttle_mode for SMBA resources

The following commit has been merged into the x86/cache branch of tip:

Commit-ID:     6c2282d42cb37f081587412f77340138b1df265e
Gitweb:        https://git.kernel.org/tip/6c2282d42cb37f081587412f77340138b1df265e
Author:        James Morse <james.morse@....com>
AuthorDate:    Tue, 11 Mar 2025 18:37:13 
Committer:     Borislav Petkov (AMD) <bp@...en8.de>
CommitterDate: Wed, 12 Mar 2025 12:24:46 +01:00

x86/resctrl: Handle throttle_mode for SMBA resources

Now that the visibility of throttle_mode is being managed by resctrl, it
should consider resources other than MBA that may have a throttle_mode.  SMBA
is one such resource.

Extend thread_throttle_mode_init() to check SMBA for a throttle_mode.

Adding support for multiple resources means it is possible for a platform with
both MBA and SMBA, but an undefined throttle_mode on one of them to make the
file visible.

Add the 'undefined' case to rdt_thread_throttle_mode_show().

Signed-off-by: James Morse <james.morse@....com>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
Reviewed-by: Fenghua Yu <fenghuay@...dia.com>
Reviewed-by: Babu Moger <babu.moger@....com>
Reviewed-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Tested-by: Peter Newman <peternewman@...gle.com>
Tested-by: Shaopeng Tan <tan.shaopeng@...fujitsu.com>
Tested-by: Amit Singh Tomar <amitsinght@...vell.com> # arm64
Tested-by: Shanker Donthineni <sdonthineni@...dia.com> # arm64
Tested-by: Babu Moger <babu.moger@....com>
Link: https://lore.kernel.org/r/20250311183715.16445-29-james.morse@arm.com
---
 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 33 ++++++++++++++++++++-----
 1 file changed, 27 insertions(+), 6 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
index 58feba3..5fc60c9 100644
--- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
+++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
@@ -1188,10 +1188,19 @@ static int rdt_thread_throttle_mode_show(struct kernfs_open_file *of,
 	struct resctrl_schema *s = of->kn->parent->priv;
 	struct rdt_resource *r = s->res;
 
-	if (r->membw.throttle_mode == THREAD_THROTTLE_PER_THREAD)
+	switch (r->membw.throttle_mode) {
+	case THREAD_THROTTLE_PER_THREAD:
 		seq_puts(seq, "per-thread\n");
-	else
+		return 0;
+	case THREAD_THROTTLE_MAX:
 		seq_puts(seq, "max\n");
+		return 0;
+	case THREAD_THROTTLE_UNDEFINED:
+		seq_puts(seq, "undefined\n");
+		return 0;
+	}
+
+	WARN_ON_ONCE(1);
 
 	return 0;
 }
@@ -2066,12 +2075,24 @@ static struct rftype *rdtgroup_get_rftype_by_name(const char *name)
 
 static void thread_throttle_mode_init(void)
 {
-	struct rdt_resource *r_mba;
+	enum membw_throttle_mode throttle_mode = THREAD_THROTTLE_UNDEFINED;
+	struct rdt_resource *r_mba, *r_smba;
 
 	r_mba = resctrl_arch_get_resource(RDT_RESOURCE_MBA);
-	if (r_mba->membw.throttle_mode != THREAD_THROTTLE_UNDEFINED)
-		resctrl_file_fflags_init("thread_throttle_mode",
-					 RFTYPE_CTRL_INFO | RFTYPE_RES_MB);
+	if (r_mba->alloc_capable &&
+	    r_mba->membw.throttle_mode != THREAD_THROTTLE_UNDEFINED)
+		throttle_mode = r_mba->membw.throttle_mode;
+
+	r_smba = resctrl_arch_get_resource(RDT_RESOURCE_SMBA);
+	if (r_smba->alloc_capable &&
+	    r_smba->membw.throttle_mode != THREAD_THROTTLE_UNDEFINED)
+		throttle_mode = r_smba->membw.throttle_mode;
+
+	if (throttle_mode == THREAD_THROTTLE_UNDEFINED)
+		return;
+
+	resctrl_file_fflags_init("thread_throttle_mode",
+				 RFTYPE_CTRL_INFO | RFTYPE_RES_MB);
 }
 
 void resctrl_file_fflags_init(const char *config, unsigned long fflags)