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From: guoren@kernel.org
To: paul.walmsley@sifive.com, palmer@dabbelt.com, guoren@kernel.org,
	panqinglin2020@iscas.ac.cn, bjorn@rivosinc.com,
	conor.dooley@microchip.com, leobras@redhat.com,
	peterz@infradead.org, anup@brainfault.org, keescook@chromium.org,
	wuwei2016@iscas.ac.cn, xiaoguang.xing@sophgo.com,
	chao.wei@sophgo.com, unicorn_wang@outlook.com, uwu@icenowy.me,
	jszhang@kernel.org, wefu@redhat.com, atishp@atishpatra.org
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	Guo Ren <guoren@linux.alibaba.com>
Subject: [PATCH V12 12/14] RISC-V: paravirt: pvqspinlock: Add nopvspin kernel parameter
Date: Mon, 25 Dec 2023 07:58:45 -0500	[thread overview]
Message-ID: <20231225125847.2778638-13-guoren@kernel.org> (raw)
In-Reply-To: <20231225125847.2778638-1-guoren@kernel.org>

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

Disables the qspinlock slow path using PV optimizations which
allow the hypervisor to 'idle' the guest on lock contention.

Reviewed-by: Leonardo Bras <leobras@redhat.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  2 +-
 arch/riscv/kernel/qspinlock_paravirt.c          | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b7794c96d91e..4aff81d741e2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3927,7 +3927,7 @@
 			as generic guest with no PV drivers. Currently support
 			XEN HVM, KVM, HYPER_V and VMWARE guest.
 
-	nopvspin	[X86,XEN,KVM]
+	nopvspin	[X86,XEN,KVM,RISC-V]
 			Disables the qspinlock slow path using PV optimizations
 			which allow the hypervisor to 'idle' the guest on lock
 			contention.
diff --git a/arch/riscv/kernel/qspinlock_paravirt.c b/arch/riscv/kernel/qspinlock_paravirt.c
index 7d1b99412222..4b04c93c4b9b 100644
--- a/arch/riscv/kernel/qspinlock_paravirt.c
+++ b/arch/riscv/kernel/qspinlock_paravirt.c
@@ -43,8 +43,21 @@ EXPORT_STATIC_CALL(pv_queued_spin_lock_slowpath);
 DEFINE_STATIC_CALL(pv_queued_spin_unlock, native_queued_spin_unlock);
 EXPORT_STATIC_CALL(pv_queued_spin_unlock);
 
+static bool nopvspin __initdata;
+static __init int parse_nopvspin(char *arg)
+{
+       nopvspin = true;
+       return 0;
+}
+early_param("nopvspin", parse_nopvspin);
+
 void __init pv_qspinlock_init(void)
 {
+	if (nopvspin) {
+		pr_info("PV qspinlocks disabled\n");
+		return;
+	}
+
 	if (num_possible_cpus() == 1)
 		return;
 
-- 
2.40.1


_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-riscv

WARNING: multiple messages have this Message-ID (diff)
From: guoren@kernel.org
To: paul.walmsley@sifive.com, palmer@dabbelt.com, guoren@kernel.org,
	panqinglin2020@iscas.ac.cn, bjorn@rivosinc.com,
	conor.dooley@microchip.com, leobras@redhat.com,
	peterz@infradead.org, anup@brainfault.org, keescook@chromium.org,
	wuwei2016@iscas.ac.cn, xiaoguang.xing@sophgo.com,
	chao.wei@sophgo.com, unicorn_wang@outlook.com, uwu@icenowy.me,
	jszhang@kernel.org, wefu@redhat.com, atishp@atishpatra.org
Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org,
	kvm@vger.kernel.org, virtualization@lists.linux-foundation.org,
	Guo Ren <guoren@linux.alibaba.com>
Subject: [PATCH V12 12/14] RISC-V: paravirt: pvqspinlock: Add nopvspin kernel parameter
Date: Mon, 25 Dec 2023 07:58:45 -0500	[thread overview]
Message-ID: <20231225125847.2778638-13-guoren@kernel.org> (raw)
In-Reply-To: <20231225125847.2778638-1-guoren@kernel.org>

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

Disables the qspinlock slow path using PV optimizations which
allow the hypervisor to 'idle' the guest on lock contention.

Reviewed-by: Leonardo Bras <leobras@redhat.com>
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
 Documentation/admin-guide/kernel-parameters.txt |  2 +-
 arch/riscv/kernel/qspinlock_paravirt.c          | 13 +++++++++++++
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b7794c96d91e..4aff81d741e2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3927,7 +3927,7 @@
 			as generic guest with no PV drivers. Currently support
 			XEN HVM, KVM, HYPER_V and VMWARE guest.
 
-	nopvspin	[X86,XEN,KVM]
+	nopvspin	[X86,XEN,KVM,RISC-V]
 			Disables the qspinlock slow path using PV optimizations
 			which allow the hypervisor to 'idle' the guest on lock
 			contention.
diff --git a/arch/riscv/kernel/qspinlock_paravirt.c b/arch/riscv/kernel/qspinlock_paravirt.c
index 7d1b99412222..4b04c93c4b9b 100644
--- a/arch/riscv/kernel/qspinlock_paravirt.c
+++ b/arch/riscv/kernel/qspinlock_paravirt.c
@@ -43,8 +43,21 @@ EXPORT_STATIC_CALL(pv_queued_spin_lock_slowpath);
 DEFINE_STATIC_CALL(pv_queued_spin_unlock, native_queued_spin_unlock);
 EXPORT_STATIC_CALL(pv_queued_spin_unlock);
 
+static bool nopvspin __initdata;
+static __init int parse_nopvspin(char *arg)
+{
+       nopvspin = true;
+       return 0;
+}
+early_param("nopvspin", parse_nopvspin);
+
 void __init pv_qspinlock_init(void)
 {
+	if (nopvspin) {
+		pr_info("PV qspinlocks disabled\n");
+		return;
+	}
+
 	if (num_possible_cpus() == 1)
 		return;
 
-- 
2.40.1


  parent reply	other threads:[~2023-12-25 13:00 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-25 12:58 [PATCH V12 00/14] riscv: Add Native/Paravirt qspinlock support guoren
2023-12-25 12:58 ` guoren
2023-12-25 12:58 ` [PATCH V12 01/14] asm-generic: ticket-lock: Reuse arch_spinlock_t of qspinlock guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 02/14] asm-generic: ticket-lock: Add separate ticket-lock.h guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 03/14] riscv: errata: Move errata vendor func-id into vendorid_list.h guoren
2023-12-25 12:58   ` guoren
2024-01-04  4:00   ` Leonardo Bras
2024-01-04  4:00     ` Leonardo Bras
2023-12-25 12:58 ` [PATCH V12 04/14] riscv: qspinlock: errata: Add ERRATA_THEAD_WRITE_ONCE fixup guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 05/14] riscv: qspinlock: Add basic queued_spinlock support guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 06/14] riscv: qspinlock: Introduce combo spinlock guoren
2023-12-25 12:58   ` guoren
2024-01-04  4:56   ` Leonardo Bras
2024-01-04  4:56     ` Leonardo Bras
2023-12-25 12:58 ` [PATCH V12 07/14] riscv: qspinlock: Add virt_spin_lock() support for VM guest guoren
2023-12-25 12:58   ` guoren
2024-01-04  5:06   ` Leonardo Bras
2024-01-04  5:06     ` Leonardo Bras
2023-12-25 12:58 ` [PATCH V12 08/14] riscv: qspinlock: Force virt_spin_lock for KVM guests guoren
2023-12-25 12:58   ` guoren
2024-01-04  5:11   ` Leonardo Bras
2024-01-04  5:11     ` Leonardo Bras
2023-12-25 12:58 ` [PATCH V12 09/14] RISC-V: paravirt: Add pvqspinlock KVM backend guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 10/14] RISC-V: paravirt: Add pvqspinlock frontend skeleton guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 11/14] RISC-V: paravirt: pvqspinlock: Add SBI implementation guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` guoren [this message]
2023-12-25 12:58   ` [PATCH V12 12/14] RISC-V: paravirt: pvqspinlock: Add nopvspin kernel parameter guoren
2023-12-25 12:58 ` [PATCH V12 13/14] RISC-V: paravirt: pvqspinlock: Add kconfig entry guoren
2023-12-25 12:58   ` guoren
2023-12-25 12:58 ` [PATCH V12 14/14] RISC-V: paravirt: pvqspinlock: Add trace point for pv_kick/wait guoren
2023-12-25 12:58   ` guoren
2023-12-26  0:35 ` [PATCH V12 00/14] riscv: Add Native/Paravirt qspinlock support Guo Ren
2023-12-26  0:35   ` Guo Ren

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