diff mbox series

[v3,3/4] xen: Mark "xen_nopvspin" parameter obsolete and map it to "nopvspin"

Message ID 1569847479-13201-4-git-send-email-zhenzhong.duan@oracle.com (mailing list archive)
State New, archived
Headers show
Series Add a unified parameter "nopvspin" | expand

Commit Message

Zhenzhong Duan Sept. 30, 2019, 12:44 p.m. UTC 
Fix stale description of "xen_nopvspin" as we use qspinlock now.

Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
---
 Documentation/admin-guide/kernel-parameters.txt |  7 ++++---
 arch/x86/xen/spinlock.c                         | 13 +++++++------
 2 files changed, 11 insertions(+), 9 deletions(-)

Comments

Sean Christopherson Oct. 2, 2019, 5:18 p.m. UTC | #1 
On Mon, Sep 30, 2019 at 08:44:38PM +0800, Zhenzhong Duan wrote:
> Fix stale description of "xen_nopvspin" as we use qspinlock now.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
> Reviewed-by: Juergen Gross <jgross@suse.com>
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
> Cc: Juergen Gross <jgross@suse.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> ---
>  Documentation/admin-guide/kernel-parameters.txt |  7 ++++---
>  arch/x86/xen/spinlock.c                         | 13 +++++++------
>  2 files changed, 11 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 4b956d8..1f0a62f 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5303,8 +5303,9 @@
>  			never -- do not unplug even if version check succeeds
>  
>  	xen_nopvspin	[X86,XEN]
> -			Disables the ticketlock slowpath using Xen PV
> -			optimizations.
> +			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
> @@ -5330,7 +5331,7 @@
>  			as generic guest with no PV drivers. Currently support
>  			XEN HVM, KVM, HYPER_V and VMWARE guest.
>  
> -	nopvspin	[X86,KVM] Disables the qspinlock slow path
> +	nopvspin	[X86,XEN,KVM] Disables the qspinlock slow path
>  			using PV optimizations which allow the hypervisor to
>  			'idle' the guest on lock contention.
>  
> diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
> index 6deb490..092a53f 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 (!pvspin)
>  		return;
>  
>  	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
> @@ -93,7 +92,7 @@ void xen_init_lock_cpu(int cpu)
>  
>  void xen_uninit_lock_cpu(int cpu)
>  {
> -	if (!xen_pvspin)
> +	if (!pvspin)
>  		return;
>  
>  	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
> @@ -117,9 +116,9 @@ void __init xen_init_spinlocks(void)
>  
>  	/*  Don't need to use pvqspinlock code if there is only 1 vCPU. */
>  	if (num_possible_cpus() == 1)
> -		xen_pvspin = false;
> +		pvspin = false;

As suggested in the other patch, if you incorporate pvspin (or nopvspin)
into xen_pvspin then the param can be __initdata and the diff for this
patch will be smaller, e.g. you wouldn't need the xen_domain() shenanigans
in xen_parse_nopvspin().

> -	if (!xen_pvspin) {
> +	if (!pvspin) {
>  		printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
>  		static_branch_disable(&virt_spin_lock_key);
>  		return;
> @@ -137,7 +136,9 @@ void __init xen_init_spinlocks(void)
>  
>  static __init int xen_parse_nopvspin(char *arg)
>  {
> -	xen_pvspin = false;
> +	pr_notice("\"xen_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
> +	if (xen_domain())
> +		pvspin = false;
>  	return 0;
>  }
>  early_param("xen_nopvspin", xen_parse_nopvspin);
> -- 
> 1.8.3.1
>
Zhenzhong Duan Oct. 3, 2019, 11:21 a.m. UTC | #2 
On 2019/10/3 1:18, Sean Christopherson wrote:
> On Mon, Sep 30, 2019 at 08:44:38PM +0800, Zhenzhong Duan wrote:
>> Fix stale description of "xen_nopvspin" as we use qspinlock now.
>>
>> Signed-off-by: Zhenzhong Duan<zhenzhong.duan@oracle.com>
>> Reviewed-by: Juergen Gross<jgross@suse.com>
>> Cc: Jonathan Corbet<corbet@lwn.net>
>> Cc: Boris Ostrovsky<boris.ostrovsky@oracle.com>
>> Cc: Juergen Gross<jgross@suse.com>
>> Cc: Stefano Stabellini<sstabellini@kernel.org>
>> Cc: Thomas Gleixner<tglx@linutronix.de>
>> Cc: Ingo Molnar<mingo@redhat.com>
>> Cc: Borislav Petkov<bp@alien8.de>
>> Cc: "H. Peter Anvin"<hpa@zytor.com>
>> ---
...snip
>> @@ -93,7 +92,7 @@ void xen_init_lock_cpu(int cpu)
>>   
>>   void xen_uninit_lock_cpu(int cpu)
>>   {
>> -	if (!xen_pvspin)
>> +	if (!pvspin)
>>   		return;
>>   
>>   	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
>> @@ -117,9 +116,9 @@ void __init xen_init_spinlocks(void)
>>   
>>   	/*  Don't need to use pvqspinlock code if there is only 1 vCPU. */
>>   	if (num_possible_cpus() == 1)
>> -		xen_pvspin = false;
>> +		pvspin = false;
> As suggested in the other patch, if you incorporate pvspin (or nopvspin)
> into xen_pvspin then the param can be __initdata and the diff for this
> patch will be smaller, e.g. you wouldn't need the xen_domain() shenanigans
> in xen_parse_nopvspin().

Ok, will fix. Thanks

Zhenzhong
diff mbox series

Patch

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 4b956d8..1f0a62f 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -5303,8 +5303,9 @@ 
 			never -- do not unplug even if version check succeeds
 
 	xen_nopvspin	[X86,XEN]
-			Disables the ticketlock slowpath using Xen PV
-			optimizations.
+			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
@@ -5330,7 +5331,7 @@ 
 			as generic guest with no PV drivers. Currently support
 			XEN HVM, KVM, HYPER_V and VMWARE guest.
 
-	nopvspin	[X86,KVM] Disables the qspinlock slow path
+	nopvspin	[X86,XEN,KVM] Disables the qspinlock slow path
 			using PV optimizations which allow the hypervisor to
 			'idle' the guest on lock contention.
 
diff --git a/arch/x86/xen/spinlock.c b/arch/x86/xen/spinlock.c
index 6deb490..092a53f 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 (!pvspin)
 		return;
 
 	WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
@@ -93,7 +92,7 @@  void xen_init_lock_cpu(int cpu)
 
 void xen_uninit_lock_cpu(int cpu)
 {
-	if (!xen_pvspin)
+	if (!pvspin)
 		return;
 
 	unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
@@ -117,9 +116,9 @@  void __init xen_init_spinlocks(void)
 
 	/*  Don't need to use pvqspinlock code if there is only 1 vCPU. */
 	if (num_possible_cpus() == 1)
-		xen_pvspin = false;
+		pvspin = false;
 
-	if (!xen_pvspin) {
+	if (!pvspin) {
 		printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
 		static_branch_disable(&virt_spin_lock_key);
 		return;
@@ -137,7 +136,9 @@  void __init xen_init_spinlocks(void)
 
 static __init int xen_parse_nopvspin(char *arg)
 {
-	xen_pvspin = false;
+	pr_notice("\"xen_nopvspin\" is deprecated, please use \"nopvspin\" instead\n");
+	if (xen_domain())
+		pvspin = false;
 	return 0;
 }
 early_param("xen_nopvspin", xen_parse_nopvspin);