linux-kernel - [PATCH v6 28/42] x86/resctrl: Handle throttle

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20250207181823.6378-29-james.morse@arm.com>
Date: Fri,  7 Feb 2025 18:18:09 +0000
From: James Morse <james.morse@....com>
To: x86@...nel.org,
	linux-kernel@...r.kernel.org
Cc: Reinette Chatre <reinette.chatre@...el.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	H Peter Anvin <hpa@...or.com>,
	Babu Moger <Babu.Moger@....com>,
	James Morse <james.morse@....com>,
	shameerali.kolothum.thodi@...wei.com,
	D Scott Phillips OS <scott@...amperecomputing.com>,
	carl@...amperecomputing.com,
	lcherian@...vell.com,
	bobo.shaobowang@...wei.com,
	tan.shaopeng@...itsu.com,
	baolin.wang@...ux.alibaba.com,
	Jamie Iles <quic_jiles@...cinc.com>,
	Xin Hao <xhao@...ux.alibaba.com>,
	peternewman@...gle.com,
	dfustini@...libre.com,
	amitsinght@...vell.com,
	David Hildenbrand <david@...hat.com>,
	Rex Nie <rex.nie@...uarmicro.com>,
	Dave Martin <dave.martin@....com>,
	Koba Ko <kobak@...dia.com>,
	Shanker Donthineni <sdonthineni@...dia.com>
Subject: [PATCH v6 28/42] 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 resctrl_file_fflags_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>
---
 Changes since v5:
  * This change split out of the previous patch.
---
 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 58feba3feefd..5fc60c9ce28f 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)
-- 
2.39.2