linux-kernel - [PATCH v2 4/4] x86/hyperv: Mark "hv_nopvspin" parameter obsolete and map it to "nopvspin"

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Date:   Mon, 30 Sep 2019 20:09:00 +0800
From:   Zhenzhong Duan <zhenzhong.duan@...cle.com>
To:     linux-kernel@...r.kernel.org
Cc:     vkuznets@...hat.com, linux-hyperv@...r.kernel.org,
        kvm@...r.kernel.org, Zhenzhong Duan <zhenzhong.duan@...cle.com>,
        Jonathan Corbet <corbet@....net>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v2 4/4] x86/hyperv: Mark "hv_nopvspin" parameter obsolete and map it to "nopvspin"

Includes asm/hypervisor.h in order to reference x86_hyper_type.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
Cc: Jonathan Corbet <corbet@....net>
Cc: "K. Y. Srinivasan" <kys@...rosoft.com>
Cc: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: Stephen Hemminger <sthemmin@...rosoft.com>
Cc: Sasha Levin <sashal@...nel.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
---
 Documentation/admin-guide/kernel-parameters.txt | 6 +++++-
 arch/x86/hyperv/hv_spinlock.c                   | 9 +++++----
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 1f0a62f..43f922c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1436,6 +1436,10 @@
 	hv_nopvspin	[X86,HYPER_V] Disables the paravirt spinlock optimizations
 				      which allow the hypervisor to 'idle' the
 				      guest on lock contention.
+				      This parameter is obsoleted by "nopvspin"
+				      parameter, which has equivalent effect for
+				      HYPER_V platform.
+
 
 	keep_bootcon	[KNL]
 			Do not unregister boot console at start. This is only
@@ -5331,7 +5335,7 @@
 			as generic guest with no PV drivers. Currently support
 			XEN HVM, KVM, HYPER_V and VMWARE guest.
 
-	nopvspin	[X86,XEN,KVM] Disables the qspinlock slow path
+	nopvspin	[X86,XEN,KVM,HYPER_V] Disables the qspinlock slow path
 			using PV optimizations which allow the hypervisor to
 			'idle' the guest on lock contention.
 
diff --git a/arch/x86/hyperv/hv_spinlock.c b/arch/x86/hyperv/hv_spinlock.c
index 07f21a0..e00e319 100644
--- a/arch/x86/hyperv/hv_spinlock.c
+++ b/arch/x86/hyperv/hv_spinlock.c
@@ -12,12 +12,11 @@
 
 #include <linux/spinlock.h>
 
+#include <asm/hypervisor.h>
 #include <asm/mshyperv.h>
 #include <asm/paravirt.h>
 #include <asm/apic.h>
 
-static bool __initdata hv_pvspin = true;
-
 static void hv_qlock_kick(int cpu)
 {
 	apic->send_IPI(cpu, X86_PLATFORM_IPI_VECTOR);
@@ -64,7 +63,7 @@ __visible bool hv_vcpu_is_preempted(int vcpu)
 
 void __init hv_init_spinlocks(void)
 {
-	if (!hv_pvspin || !apic ||
+	if (!pvspin || !apic ||
 	    !(ms_hyperv.hints & HV_X64_CLUSTER_IPI_RECOMMENDED) ||
 	    !(ms_hyperv.features & HV_X64_MSR_GUEST_IDLE_AVAILABLE)) {
 		pr_info("PV spinlocks disabled\n");
@@ -82,7 +81,9 @@ void __init hv_init_spinlocks(void)
 
 static __init int hv_parse_nopvspin(char *arg)
 {
-	hv_pvspin = false;
+	pr_notice("\"hv_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
+	if (x86_hyper_type == X86_HYPER_MS_HYPERV)
+		pvspin = false;
 	return 0;
 }
 early_param("hv_nopvspin", hv_parse_nopvspin);
-- 
1.8.3.1