linux/arch/x86/xen/spinlock.c
Waiman Long aef591cd3d locking/spinlocks/x86, paravirt: Remove paravirt_ticketlocks_enabled
This is a follow-up of commit:

  cfd8983f03 ("x86, locking/spinlocks: Remove ticket (spin)lock implementation")

The static_key structure 'paravirt_ticketlocks_enabled' is now removed as it is
no longer used.

As a result, the init functions kvm_spinlock_init_jump() and
xen_init_spinlocks_jump() are also removed.

A simple build and boot test was done to verify it.

Signed-off-by: Waiman Long <longman@redhat.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Alok Kataria <akataria@vmware.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: kvm@vger.kernel.org
Cc: linux-arch@vger.kernel.org
Cc: virtualization@lists.linux-foundation.org
Cc: xen-devel@lists.xenproject.org
Link: http://lkml.kernel.org/r/1484252878-1962-1-git-send-email-longman@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2017-01-14 09:33:46 +01:00

151 lines
3.5 KiB
C

/*
* Split spinlock implementation out into its own file, so it can be
* compiled in a FTRACE-compatible way.
*/
#include <linux/kernel_stat.h>
#include <linux/spinlock.h>
#include <linux/debugfs.h>
#include <linux/log2.h>
#include <linux/gfp.h>
#include <linux/slab.h>
#include <asm/paravirt.h>
#include <xen/interface/xen.h>
#include <xen/events.h>
#include "xen-ops.h"
#include "debugfs.h"
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>
static void xen_qlock_kick(int cpu)
{
int irq = per_cpu(lock_kicker_irq, cpu);
/* Don't kick if the target's kicker interrupt is not initialized. */
if (irq == -1)
return;
xen_send_IPI_one(cpu, XEN_SPIN_UNLOCK_VECTOR);
}
/*
* Halt the current CPU & release it back to the host
*/
static void xen_qlock_wait(u8 *byte, u8 val)
{
int irq = __this_cpu_read(lock_kicker_irq);
/* If kicker interrupts not initialized yet, just spin */
if (irq == -1)
return;
/* clear pending */
xen_clear_irq_pending(irq);
barrier();
/*
* We check the byte value after clearing pending IRQ to make sure
* that we won't miss a wakeup event because of the clearing.
*
* The sync_clear_bit() call in xen_clear_irq_pending() is atomic.
* So it is effectively a memory barrier for x86.
*/
if (READ_ONCE(*byte) != val)
return;
/*
* If an interrupt happens here, it will leave the wakeup irq
* pending, which will cause xen_poll_irq() to return
* immediately.
*/
/* Block until irq becomes pending (or perhaps a spurious wakeup) */
xen_poll_irq(irq);
}
static irqreturn_t dummy_handler(int irq, void *dev_id)
{
BUG();
return IRQ_HANDLED;
}
void xen_init_lock_cpu(int cpu)
{
int irq;
char *name;
if (!xen_pvspin)
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));
name = kasprintf(GFP_KERNEL, "spinlock%d", cpu);
irq = bind_ipi_to_irqhandler(XEN_SPIN_UNLOCK_VECTOR,
cpu,
dummy_handler,
IRQF_PERCPU|IRQF_NOBALANCING,
name,
NULL);
if (irq >= 0) {
disable_irq(irq); /* make sure it's never delivered */
per_cpu(lock_kicker_irq, cpu) = irq;
per_cpu(irq_name, cpu) = name;
}
printk("cpu %d spinlock event irq %d\n", cpu, irq);
}
void xen_uninit_lock_cpu(int cpu)
{
if (!xen_pvspin)
return;
unbind_from_irqhandler(per_cpu(lock_kicker_irq, cpu), NULL);
per_cpu(lock_kicker_irq, cpu) = -1;
kfree(per_cpu(irq_name, cpu));
per_cpu(irq_name, cpu) = NULL;
}
PV_CALLEE_SAVE_REGS_THUNK(xen_vcpu_stolen);
/*
* Our init of PV spinlocks is split in two init functions due to us
* using paravirt patching and jump labels patching and having to do
* all of this before SMP code is invoked.
*
* The paravirt patching needs to be done _before_ the alternative asm code
* is started, otherwise we would not patch the core kernel code.
*/
void __init xen_init_spinlocks(void)
{
if (!xen_pvspin) {
printk(KERN_DEBUG "xen: PV spinlocks disabled\n");
return;
}
printk(KERN_DEBUG "xen: PV spinlocks enabled\n");
__pv_init_lock_hash();
pv_lock_ops.queued_spin_lock_slowpath = __pv_queued_spin_lock_slowpath;
pv_lock_ops.queued_spin_unlock = PV_CALLEE_SAVE(__pv_queued_spin_unlock);
pv_lock_ops.wait = xen_qlock_wait;
pv_lock_ops.kick = xen_qlock_kick;
pv_lock_ops.vcpu_is_preempted = PV_CALLEE_SAVE(xen_vcpu_stolen);
}
static __init int xen_parse_nopvspin(char *arg)
{
xen_pvspin = false;
return 0;
}
early_param("xen_nopvspin", xen_parse_nopvspin);