linux-kernel - [PATCH] riscv: Add riscv_force_qspinlock for early

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Message-Id: <20241214043510.3795984-1-guoren@kernel.org>
Date: Fri, 13 Dec 2024 23:35:10 -0500
From: guoren@...nel.org
To: guoren@...nel.org,
	conor@...nel.org,
	alexghiti@...osinc.com
Cc: linux-riscv@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	paul.walmsley@...ive.com,
	palmer@...belt.com,
	bjorn@...osinc.com,
	leobras@...hat.com,
	peterz@...radead.org,
	parri.andrea@...il.com,
	longman@...hat.com,
	boqun.feng@...il.com,
	arnd@...db.de,
	will@...nel.org,
	corbet@....net,
	Guo Ren <guoren@...ux.alibaba.com>
Subject: [PATCH] riscv: Add riscv_force_qspinlock for early_param

From: Guo Ren <guoren@...ux.alibaba.com>

When CONFIG_RISCV_COMBO_SPINLOCKS is enabled, permit qspinlock
force enabled. See the Kconfig entry for RISCV_COMBO_SPINLOCKS.

Signed-off-by: Guo Ren <guoren@...ux.alibaba.com>
Signed-off-by: Guo Ren <guoren@...nel.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  5 +++++
 arch/riscv/kernel/setup.c                       | 13 ++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 3872bc6ec49d..43d0df2922b2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5887,6 +5887,11 @@
 			[KNL] Disable ring 3 MONITOR/MWAIT feature on supported
 			CPUs.
 
+	riscv_force_qspinlock [RISCV, EARLY]
+			When CONFIG_RISCV_COMBO_SPINLOCKS is enabled, permit
+			qspinlock force enabled. See the Kconfig entry for
+			RISCV_COMBO_SPINLOCKS.
+
 	riscv_isa_fallback [RISCV,EARLY]
 			When CONFIG_RISCV_ISA_FALLBACK is not enabled, permit
 			falling back to detecting extension support by parsing
diff --git a/arch/riscv/kernel/setup.c b/arch/riscv/kernel/setup.c
index 45010e71df86..74b13bc64c9c 100644
--- a/arch/riscv/kernel/setup.c
+++ b/arch/riscv/kernel/setup.c
@@ -247,6 +247,15 @@ static void __init parse_dtb(void)
 #if defined(CONFIG_RISCV_COMBO_SPINLOCKS)
 DEFINE_STATIC_KEY_TRUE(qspinlock_key);
 EXPORT_SYMBOL(qspinlock_key);
+
+static bool force_qspinlock;
+
+static int __init riscv_force_qspinlock(char *p)
+{
+	force_qspinlock = true;
+	return 0;
+}
+early_param("riscv_force_qspinlock", riscv_force_qspinlock);
 #endif
 
 static void __init riscv_spinlock_init(void)
@@ -267,7 +276,9 @@ static void __init riscv_spinlock_init(void)
 		using_ext = "using Ziccrse";
 	}
 #if defined(CONFIG_RISCV_COMBO_SPINLOCKS)
-	else {
+	else if (force_qspinlock) {
+		using_ext = "force";
+	} else {
 		static_branch_disable(&qspinlock_key);
 		pr_info("Ticket spinlock: enabled\n");
 		return;
-- 
2.40.1