[Xen-devel] [PATCH-tip v2 2/2] x86/xen: Deprecate xen_nopvspin

[Waiman Long <longman@xxxxxxxxxx>]

With the new pvlock_type kernel parameter, xen_nopvspin is no longer
needed. This patch deprecates the xen_nopvspin parameter by removing
its documentation and treating it as an alias of "pvlock_type=queued".

Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
---
 Documentation/admin-guide/kernel-parameters.txt |  4 ----
 arch/x86/xen/spinlock.c                         | 19 +++++++------------
 2 files changed, 7 insertions(+), 16 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt 
b/Documentation/admin-guide/kernel-parameters.txt
index c98d9c7..683a817 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -4596,10 +4596,6 @@
                                the unplug protocol
                        never -- do not unplug even if version check succeeds
 
-       xen_nopvspin    [X86,XEN]
-                       Disables the ticketlock slowpath using Xen PV
-                       optimizations.
-
        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 d5f79ac..19e2e75 100644
--- a/arch/x86/xen/spinlock.c
+++ b/arch/x86/xen/spinlock.c
@@ -20,7 +20,6 @@
 
 static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
 static DEFINE_PER_CPU(char *, irq_name);
-static bool xen_pvspin = true;
 
 #include <asm/qspinlock.h>
 
@@ -81,12 +80,8 @@ void xen_init_lock_cpu(int cpu)
        int irq;
        char *name;
 
-       if (!xen_pvspin ||
-          (pv_spinlock_type & (locktype_queued|locktype_unfair))) {
-               if ((cpu == 0) && !pv_spinlock_type)
-                       static_branch_disable(&virt_spin_lock_key);
+       if (pv_spinlock_type & (locktype_queued|locktype_unfair))
                return;
-       }
 
        WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on 
IRQ%d!\n",
             cpu, per_cpu(lock_kicker_irq, cpu));
@@ -110,8 +105,7 @@ void xen_init_lock_cpu(int cpu)
 
 void xen_uninit_lock_cpu(int cpu)
 {
-       if (!xen_pvspin ||
-          (pv_spinlock_type & (locktype_queued|locktype_unfair)))
+       if (pv_spinlock_type & (locktype_queued|locktype_unfair))
                return;
 
        unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
@@ -132,8 +126,7 @@ void xen_uninit_lock_cpu(int cpu)
  */
 void __init xen_init_spinlocks(void)
 {
-       if (!xen_pvspin ||
-          (pv_spinlock_type & (locktype_queued|locktype_unfair))) {
+       if (pv_spinlock_type & (locktype_queued|locktype_unfair)) {
                printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
                return;
        }
@@ -147,10 +140,12 @@ void __init xen_init_spinlocks(void)
        pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen);
 }
 
+/* TODO: To be removed in a future kernel version */
 static __init int xen_parse_nopvspin(char *arg)
 {
-       xen_pvspin = false;
+       pr_warn("xen_nopvspin is deprecated, replace it with 
\"pvlock_type=queued\"!\n");
+       if (!pv_spinlock_type)
+               pv_spinlock_type = locktype_queued;
        return 0;
 }
 early_param("xen_nopvspin", xen_parse_nopvspin);
-
-- 
1.8.3.1


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