x86/mm/pat: Don't report PAT on CPUs that don't support it
[linux/fpc-iii.git] / arch / x86 / xen / spinlock.c
blob25a7c4302ce70390e81f98be0df2324a725364d5
1 /*
2 * Split spinlock implementation out into its own file, so it can be
3 * compiled in a FTRACE-compatible way.
4 */
5 #include <linux/kernel_stat.h>
6 #include <linux/spinlock.h>
7 #include <linux/debugfs.h>
8 #include <linux/log2.h>
9 #include <linux/gfp.h>
10 #include <linux/slab.h>
12 #include <asm/paravirt.h>
14 #include <xen/interface/xen.h>
15 #include <xen/events.h>
17 #include "xen-ops.h"
18 #include "debugfs.h"
20 static DEFINE_PER_CPU(int, lock_kicker_irq) = -1;
21 static DEFINE_PER_CPU(char *, irq_name);
22 static bool xen_pvspin = true;
24 #include <asm/qspinlock.h>
26 static void xen_qlock_kick(int cpu)
28 int irq = per_cpu(lock_kicker_irq, cpu);
30 /* Don't kick if the target's kicker interrupt is not initialized. */
31 if (irq == -1)
32 return;
34 xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
38 * Halt the current CPU & release it back to the host
40 static void xen_qlock_wait(u8 *byte, u8 val)
42 int irq = __this_cpu_read(lock_kicker_irq);
44 /* If kicker interrupts not initialized yet, just spin */
45 if (irq == -1)
46 return;
48 /* clear pending */
49 xen_clear_irq_pending(irq);
50 barrier();
53 * We check the byte value after clearing pending IRQ to make sure
54 * that we won't miss a wakeup event because of the clearing.
56 * The sync_clear_bit() call in xen_clear_irq_pending() is atomic.
57 * So it is effectively a memory barrier for x86.
59 if (READ_ONCE(*byte) != val)
60 return;
63 * If an interrupt happens here, it will leave the wakeup irq
64 * pending, which will cause xen_poll_irq() to return
65 * immediately.
68 /* Block until irq becomes pending (or perhaps a spurious wakeup) */
69 xen_poll_irq(irq);
72 static irqreturn_t dummy_handler(int irq, void *dev_id)
74 BUG();
75 return IRQ_HANDLED;
78 void xen_init_lock_cpu(int cpu)
80 int irq;
81 char *name;
83 if (!xen_pvspin)
84 return;
86 WARN(per_cpu(lock_kicker_irq, cpu) >= 0, "spinlock on CPU%d exists on IRQ%d!\n",
87 cpu, per_cpu(lock_kicker_irq, cpu));
89 name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
90 irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
91 cpu,
92 dummy_handler,
93 IRQF_PERCPU|IRQF_NOBALANCING,
94 name,
95 NULL);
97 if (irq >= 0) {
98 disable_irq(irq); /* make sure it's never delivered */
99 per_cpu(lock_kicker_irq, cpu) = irq;
100 per_cpu(irq_name, cpu) = name;
103 printk("cpu %d spinlock event irq %d\n", cpu, irq);
106 void xen_uninit_lock_cpu(int cpu)
108 if (!xen_pvspin)
109 return;
111 unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
112 per_cpu(lock_kicker_irq, cpu) = -1;
113 kfree(per_cpu(irq_name, cpu));
114 per_cpu(irq_name, cpu) = NULL;
117 PV_CALLEE_SAVE_REGS_THUNK(xen_vcpu_stolen);
120 * Our init of PV spinlocks is split in two init functions due to us
121 * using paravirt patching and jump labels patching and having to do
122 * all of this before SMP code is invoked.
124 * The paravirt patching needs to be done _before_ the alternative asm code
125 * is started, otherwise we would not patch the core kernel code.
127 void __init xen_init_spinlocks(void)
130 if (!xen_pvspin) {
131 printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
132 return;
134 printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
136 __pv_init_lock_hash();
137 pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
138 pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
139 pv_lock_ops.wait = xen_qlock_wait;
140 pv_lock_ops.kick = xen_qlock_kick;
141 pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen);
144 static __init int xen_parse_nopvspin(char *arg)
146 xen_pvspin = false;
147 return 0;
149 early_param("xen_nopvspin", xen_parse_nopvspin);