Received-SPF: pass (google.com: domain of linux-kernel+bounces-176486-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>
To: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Aleksandar Rikalo <arikalo@gmail.com>,
	Chao-ying Fu <cfu@wavecomp.com>,
	Daniel Lezcano <daniel.lezcano@linaro.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Greg Ungerer <gerg@kernel.org>,
	Hauke Mehrtens <hauke@hauke-m.de>,
	Ilya Lipnitskiy <ilya.lipnitskiy@gmail.com>,
	Jiaxun Yang <jiaxun.yang@flygoat.com>,
	linux-kernel@vger.kernel.org,
	linux-mips@vger.kernel.org,
	Marc Zyngier <maz@kernel.org>,
	Paul Burton <paulburton@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Serge Semin <fancer.lancer@gmail.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Tiezhu Yang <yangtiezhu@loongson.cn>
Subject: [PATCH v4 09/14] MIPS: pm-cps: Use per-CPU variables as per-CPU, not per-core
Date: Sat, 11 May 2024 12:43:36 +0200
Message-Id: <20240511104341.151550-10-aleksandar.rikalo@syrmia.com>
In-Reply-To: <20240511104341.151550-1-aleksandar.rikalo@syrmia.com>
References: <20240511104341.151550-1-aleksandar.rikalo@syrmia.com>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?us-ascii?Q?6R/4RH6K04L3el6fUGLYv4FYz0wjkOlarP/s1/eVTw90O8BibI5ngJ2IjNHj?=
 =?us-ascii?Q?6wTwjzPdL1QEbku7cSoiPoQ339Evjuy2dvTcpPHWJGqhaN01Bd0lCpWGgosK?=
 =?us-ascii?Q?0STB8QiinrpWyX/z74vl94uRAj/aTLNT9R7vbwDj7fOJl7nHp36CD/Sl0F3m?=
 =?us-ascii?Q?JrjKz6/ElrNs835cPYlO6ZdbRKBc45jm+8S0R4V7VrWf7kxA6BJN4Cjvq/c4?=
 =?us-ascii?Q?IcwqdGp2VryunRmYx6w5FRakHGA4DxDBIb2wzPFtjuqGqT3jC0OmL+QHXH8f?=
 =?us-ascii?Q?wu9rvQWRNMNm1zlDlDiBVkAAhKg5l1R9/akWHfnrvEErCwYVQT7mtBmmg9X0?=
 =?us-ascii?Q?ue6abEKkOKvD5G8tGjeem4kwp2qCFmXcszawa7N+Z9uaS6LzMtFT9C3bdQoo?=
 =?us-ascii?Q?9ZsgWWkV1nnvhAY+x1/azBjUar/fNnZw2b2U7NXz1fLyNzmE+ePKTfp6si17?=
 =?us-ascii?Q?5BqlUVpTyVXeZZ7tMM7ubzrcqGQFiyC6weKvSo+jR815L46gq0Kb4o+2HEqc?=
 =?us-ascii?Q?LEbANmKS0ht5/MUI2SZh18r63UF9dJB1waK9hOpg5VXAeJ3naqOq4NhPvi+f?=
 =?us-ascii?Q?zfSLtLWR/Wm952/eJhiujKcJlv6bUAC9pscj+oZ84++B7+BiCdwk+tvwCdYS?=
 =?us-ascii?Q?ptY3oqMtcvdlAv0K6RWxyWuwq57qlg2+g708/eYALBHW6AnYFjW5HZnh6GfC?=
 =?us-ascii?Q?UXx+wnsFYZXDUn/4wdcA4x25KICZByqy4cp08ObaKsrzjUli0fd5GQzybWTB?=
 =?us-ascii?Q?rialWO3SY8w9VuW0g6bkYqwuwWMGqwNE6vRZFi2C4ZSEa08K0+qMuk6h8YOg?=
 =?us-ascii?Q?Fj9JcqP16HkvHeJtNlfFYvPfPzj3496n5t5KYHqwU8FRAqqCGeftMM3lbW/j?=
 =?us-ascii?Q?wO2K0xR5AYZYmmB8xCuHr8YcJGVVzjuomdPL1qK1D6ni8es0pGZxPH6aLmxK?=
 =?us-ascii?Q?VsNZYUklT+n7OdLHcOLDQNk8C11Y5JmfvOc5uorAThQbAiAZ1BkPtpjQTmng?=
 =?us-ascii?Q?xrypVYR+4Qy1pY6V33Yrm3XEcO/v4FW/rkHw7DEiurMn00/QCzeePEWuQiQn?=
 =?us-ascii?Q?YRab8va43MNkr0JPrNVyY3IMT5I1Zj47zlmL99jz0qKGFu36AOntR2R9wIxz?=
 =?us-ascii?Q?q0t4RvAY4BxDb/t01iIQZn+yymWuN3rBRCkgg6N0ZQLXu97W1eww3hxSbR/E?=
 =?us-ascii?Q?UKAfqJcGtHWArH9t2vya+OcUgj2A5HeCY4GQrVKwmgzqK3U2lhcyLFGSTL9C?=
 =?us-ascii?Q?DUHO0mAv2OO/RftF+93iYwuTWUS8kuDiJabGLmzPoz/jC7NVBzbg2FBnqsPf?=
 =?us-ascii?Q?yTcTSbPy2SmjMwETilT9xENTvIcDU68Wh+EcefMhxzhTNmZPjNJXDekmmGZE?=
 =?us-ascii?Q?3gTPo2B4+I5jnrEe7nhv866MMp5PdLDePkh8iQOvoyzNTQIA9QatweSMbIQP?=
 =?us-ascii?Q?JAYJPQqYwKsgeisF69Qbo3Ohey4aAboGfEVOiP868xThyLv7pVrNdII/2mGD?=
 =?us-ascii?Q?xtKnNgCvdKEyCXmkHhrN/nfc+RWkYxy3eZz5c0PTUzlZAnNs3FmdfFnokzbS?=
 =?us-ascii?Q?XY2O5HQc1zTEBhb0/h72BlJ0adhEXoN81373ll4yvoD7E8Otuafinbc6uMZN?=
 =?us-ascii?Q?7Q=3D=3D?=
X-OriginatorOrg: syrmia.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 7fcdf014-855e-4889-54d9-08dc71a742ba
X-MS-Exchange-CrossTenant-AuthSource: AM9PR03MB6916.eurprd03.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 11 May 2024 10:43:57.3692
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 19214a73-c1ab-4e19-8f59-14bdcb09a66e
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: U+RmZhF1oAPFE70qHiHG80TEm1Kw7eN2DnSJZHQhiKvKqIQXbChsNyx/9V9Q9OcrBGcU5mC8jqtcbJZCjulCcjygt2OGLaQZWWtMfFKGFWM=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: GVXPR03MB8449

From: Paul Burton <paulburton@kernel.org>

The pm-cps code has up until now used per-CPU variables indexed by core,
rather than CPU number, in order to share data amongst sibling CPUs (ie.
VPs/threads in a core). This works fine for single cluster systems, but
with multi-cluster systems a core number is no longer unique in the
system, leading to sharing between CPUs that are not actually siblings.

Avoid this issue by using per-CPU variables as they are more generally
used - ie. access them using CPU numbers rather than core numbers.
Sharing between siblings is then accomplished by:
 - Assigning the same pointer to entries for each sibling CPU for the
   nc_asm_enter & ready_count variables, which allow this by virtue of
   being per-CPU pointers.

 - Indexing by the first CPU set in a CPUs cpu_sibling_map in the case
   of pm_barrier, for which we can't use the previous approach because
   the per-CPU variable is not a pointer.

Signed-off-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@syrmia.com>
Signed-off-by: Aleksandar Rikalo <aleksandar.rikalo@syrmia.com>
---
 arch/mips/kernel/pm-cps.c | 30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

diff --git a/arch/mips/kernel/pm-cps.c b/arch/mips/kernel/pm-cps.c
index d09ca77e624d..9369a8dc385e 100644
--- a/arch/mips/kernel/pm-cps.c
+++ b/arch/mips/kernel/pm-cps.c
@@ -57,10 +57,7 @@ static DEFINE_PER_CPU_ALIGNED(u32*, ready_count);
 /* Indicates online CPUs coupled with the current CPU */
 static DEFINE_PER_CPU_ALIGNED(cpumask_t, online_coupled);
 
-/*
- * Used to synchronize entry to deep idle states. Actually per-core rather
- * than per-CPU.
- */
+/* Used to synchronize entry to deep idle states */
 static DEFINE_PER_CPU_ALIGNED(atomic_t, pm_barrier);
 
 /* Saved CPU state across the CPS_PM_POWER_GATED state */
@@ -112,9 +109,10 @@ int cps_pm_enter_state(enum cps_pm_state state)
 	cps_nc_entry_fn entry;
 	struct core_boot_config *core_cfg;
 	struct vpe_boot_config *vpe_cfg;
+	atomic_t *barrier;
 
 	/* Check that there is an entry function for this state */
-	entry = per_cpu(nc_asm_enter, core)[state];
+	entry = per_cpu(nc_asm_enter, cpu)[state];
 	if (!entry)
 		return -EINVAL;
 
@@ -150,7 +148,7 @@ int cps_pm_enter_state(enum cps_pm_state state)
 	smp_mb__after_atomic();
 
 	/* Create a non-coherent mapping of the core ready_count */
-	core_ready_count = per_cpu(ready_count, core);
+	core_ready_count = per_cpu(ready_count, cpu);
 	nc_addr = kmap_noncoherent(virt_to_page(core_ready_count),
 				   (unsigned long)core_ready_count);
 	nc_addr += ((unsigned long)core_ready_count & ~PAGE_MASK);
@@ -158,7 +156,8 @@ int cps_pm_enter_state(enum cps_pm_state state)
 
 	/* Ensure ready_count is zero-initialised before the assembly runs */
 	WRITE_ONCE(*nc_core_ready_count, 0);
-	coupled_barrier(&per_cpu(pm_barrier, core), online);
+	barrier = &per_cpu(pm_barrier, cpumask_first(&cpu_sibling_map[cpu]));
+	coupled_barrier(barrier, online);
 
 	/* Run the generated entry code */
 	left = entry(online, nc_core_ready_count);
@@ -629,12 +628,14 @@ static void *cps_gen_entry_code(unsigned cpu, enum cps_pm_state state)
 
 static int cps_pm_online_cpu(unsigned int cpu)
 {
-	enum cps_pm_state state;
-	unsigned core = cpu_core(&cpu_data[cpu]);
+	unsigned int sibling, core;
 	void *entry_fn, *core_rc;
+	enum cps_pm_state state;
+
+	core = cpu_core(&cpu_data[cpu]);
 
 	for (state = CPS_PM_NC_WAIT; state < CPS_PM_STATE_COUNT; state++) {
-		if (per_cpu(nc_asm_enter, core)[state])
+		if (per_cpu(nc_asm_enter, cpu)[state])
 			continue;
 		if (!test_bit(state, state_support))
 			continue;
@@ -646,16 +647,19 @@ static int cps_pm_online_cpu(unsigned int cpu)
 			clear_bit(state, state_support);
 		}
 
-		per_cpu(nc_asm_enter, core)[state] = entry_fn;
+		for_each_cpu(sibling, &cpu_sibling_map[cpu])
+			per_cpu(nc_asm_enter, sibling)[state] = entry_fn;
 	}
 
-	if (!per_cpu(ready_count, core)) {
+	if (!per_cpu(ready_count, cpu)) {
 		core_rc = kmalloc(sizeof(u32), GFP_KERNEL);
 		if (!core_rc) {
 			pr_err("Failed allocate core %u ready_count\n", core);
 			return -ENOMEM;
 		}
-		per_cpu(ready_count, core) = core_rc;
+
+		for_each_cpu(sibling, &cpu_sibling_map[cpu])
+			per_cpu(ready_count, sibling) = core_rc;
 	}
 
 	return 0;
-- 
2.25.1