linux-kernel - [PATCH] x86/xen: remove deprecated xen

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Message-ID: <20240710110139.22300-1-jgross@suse.com>
Date: Wed, 10 Jul 2024 13:01:39 +0200
From: Juergen Gross <jgross@...e.com>
To: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	linux-doc@...r.kernel.org
Cc: Juergen Gross <jgross@...e.com>,
	Jonathan Corbet <corbet@....net>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Will Deacon <will@...nel.org>,
	Waiman Long <longman@...hat.com>,
	Boqun Feng <boqun.feng@...il.com>,
	xen-devel@...ts.xenproject.org
Subject: [PATCH] x86/xen: remove deprecated xen_nopvspin boot parameter

The xen_nopvspin boot parameter is deprecated since 2019. nopvspin
can be used instead.

Remove the xen_nopvspin boot parameter and replace the xen_pvspin
variable use cases with nopvspin.

This requires to move the nopvspin variable out of the .initdata
section, as it needs to be accessed for cpuhotplug, too.

Signed-off-by: Juergen Gross <jgross@...e.com>
---
 .../admin-guide/kernel-parameters.txt         |  5 -----
 arch/x86/xen/spinlock.c                       | 20 +++++--------------
 kernel/locking/qspinlock.c                    |  2 +-
 3 files changed, 6 insertions(+), 21 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index b33d048e01d8..2074ba03f2e3 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -7439,11 +7439,6 @@
 			access functions when running as Xen PV guest. The
 			default value is controlled by CONFIG_XEN_PV_MSR_SAFE.
 
-	xen_nopvspin	[X86,XEN,EARLY]
-			Disables the qspinlock slowpath using Xen PV optimizations.
-			This parameter is obsoleted by "nopvspin" parameter, which
-			has equivalent effect for XEN platform.
-
 	xen_nopv	[X86]
 			Disables the PV optimizations forcing the HVM guest to
 			run as generic HVM guest with no PV drivers.
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 5c6fc16e4b92..8e4efe0fb6f9 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -18,7 +18,6 @@
 static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
 static DEFINE_PER_CPU(char *, irq_name);
 static DEFINE_PER_CPU(atomic_t, xen_qlock_wait_nest);
-static bool xen_pvspin = true;
 
 static void xen_qlock_kick(int cpu)
 {
@@ -68,7 +67,7 @@ void xen_init_lock_cpu(int cpu)
 	int irq;
 	char *name;
 
-	if (!xen_pvspin)
+	if (nopvspin)
 		return;
 
 	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
@@ -95,7 +94,7 @@ void xen_uninit_lock_cpu(int cpu)
 {
 	int irq;
 
-	if (!xen_pvspin)
+	if (nopvspin)
 		return;
 
 	kfree(per_cpu(irq_name, cpu));
@@ -125,10 +124,10 @@ PV_CALLEE_SAVE_REGS_THUNK(xen_vcpu_stolen);
 void __init xen_init_spinlocks(void)
 {
 	/*  Don't need to use pvqspinlock code if there is only 1 vCPU. */
-	if (num_possible_cpus() == 1 || nopvspin)
-		xen_pvspin = false;
+	if (num_possible_cpus() == 1)
+		nopvspin = true;
 
-	if (!xen_pvspin) {
+	if (nopvspin) {
 		printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
 		static_branch_disable(&virt_spin_lock_key);
 		return;
@@ -143,12 +142,3 @@ void __init xen_init_spinlocks(void)
 	pv_ops.lock.kick = xen_qlock_kick;
 	pv_ops.lock.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen);
 }
-
-static __init int xen_parse_nopvspin(char *arg)
-{
-	pr_notice("\"xen_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
-	xen_pvspin = false;
-	return 0;
-}
-early_param("xen_nopvspin", xen_parse_nopvspin);
-
diff --git a/kernel/locking/qspinlock.c b/kernel/locking/qspinlock.c
index 1df5fef8a656..7d96bed718e4 100644
--- a/kernel/locking/qspinlock.c
+++ b/kernel/locking/qspinlock.c
@@ -583,7 +583,7 @@ EXPORT_SYMBOL(queued_spin_lock_slowpath);
 #include "qspinlock_paravirt.h"
 #include "qspinlock.c"
 
-bool nopvspin __initdata;
+bool nopvspin;
 static __init int parse_nopvspin(char *arg)
 {
 	nopvspin = true;
-- 
2.43.0