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Message-Id: <201606011201.u51Bx1UP015962@mx0a-001b2d01.pphosted.com>
Date: Wed, 1 Jun 2016 20:00:45 +0800
From: Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
To: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.orgv,
irtualization@...ts.linux-foundation.org
Cc: benh@...nel.crashing.org, paulus@...ba.org, mpe@...erman.id.au,
peterz@...radead.org, mingo@...hat.com, paulmck@...ux.vnet.ibm.com,
waiman.long@....com, Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
Subject: [PATCH v4 4/6] pv-qspinlock: powerpc support pv-qspinlock
As we need let pv-qspinlock-kernel run on all environment which might
have no powervm, we should runtime choose which qspinlock version to
use.
The default pv-qspinlock use native version. pv_lock initialization
should be done in bootstage with irq disabled. And if there is PHYP,
restore pv_lock_ops callbacks to pv version.
There is also a hash table, we store cpu number into it and the key is
lock. So everytime pv_wait can know who is the lock holder by searching
the lock. Also store the lock in a per_cpu struct, and remove it when we
own the lock. pv_wait need know which lock we are spinning on.
Signed-off-by: Pan Xinhui <xinhui.pan@...ux.vnet.ibm.com>
---
arch/powerpc/include/asm/qspinlock.h | 15 +++
arch/powerpc/include/asm/qspinlock_paravirt.h | 38 +++++++
.../powerpc/include/asm/qspinlock_paravirt_types.h | 13 +++
arch/powerpc/kernel/paravirt.c | 121 +++++++++++++++++++++
arch/powerpc/platforms/pseries/setup.c | 5 +
5 files changed, 192 insertions(+)
create mode 100644 arch/powerpc/include/asm/qspinlock_paravirt.h
create mode 100644 arch/powerpc/include/asm/qspinlock_paravirt_types.h
create mode 100644 arch/powerpc/kernel/paravirt.c
diff --git a/arch/powerpc/include/asm/qspinlock.h b/arch/powerpc/include/asm/qspinlock.h
index 5883954..35ac65a 100644
--- a/arch/powerpc/include/asm/qspinlock.h
+++ b/arch/powerpc/include/asm/qspinlock.h
@@ -12,10 +12,25 @@ static inline void native_queued_spin_unlock(struct qspinlock *lock)
smp_store_release((u8 *)lock, 0);
}
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+
+#include <asm/qspinlock_paravirt.h>
+
+static inline void queued_spin_lock_slowpath(struct qspinlock *lock, u32 val)
+{
+ pv_queued_spin_lock(lock, val);
+}
+
+static inline void queued_spin_unlock(struct qspinlock *lock)
+{
+ pv_queued_spin_unlock(lock);
+}
+#else
static inline void queued_spin_unlock(struct qspinlock *lock)
{
native_queued_spin_unlock(lock);
}
+#endif
#include <asm-generic/qspinlock.h>
diff --git a/arch/powerpc/include/asm/qspinlock_paravirt.h b/arch/powerpc/include/asm/qspinlock_paravirt.h
new file mode 100644
index 0000000..cd17a79
--- /dev/null
+++ b/arch/powerpc/include/asm/qspinlock_paravirt.h
@@ -0,0 +1,38 @@
+#ifndef CONFIG_PARAVIRT_SPINLOCKS
+#error "do not include this file"
+#endif
+
+#ifndef _ASM_QSPINLOCK_PARAVIRT_H
+#define _ASM_QSPINLOCK_PARAVIRT_H
+
+#include <asm/qspinlock_paravirt_types.h>
+
+extern void pv_lock_init(void);
+extern void native_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
+extern void __pv_init_lock_hash(void);
+extern void __pv_queued_spin_lock_slowpath(struct qspinlock *lock, u32 val);
+extern void __pv_queued_spin_unlock(struct qspinlock *lock);
+
+static inline void pv_queued_spin_lock(struct qspinlock *lock, u32 val)
+{
+ CLEAR_IO_SYNC;
+ pv_lock_op.lock(lock, val);
+}
+
+static inline void pv_queued_spin_unlock(struct qspinlock *lock)
+{
+ SYNC_IO;
+ pv_lock_op.unlock(lock);
+}
+
+static inline void pv_wait(u8 *ptr, u8 val, int lockcpu)
+{
+ pv_lock_op.wait(ptr, val, lockcpu);
+}
+
+static inline void pv_kick(int cpu)
+{
+ pv_lock_op.kick(cpu);
+}
+
+#endif
diff --git a/arch/powerpc/include/asm/qspinlock_paravirt_types.h b/arch/powerpc/include/asm/qspinlock_paravirt_types.h
new file mode 100644
index 0000000..e1fdeb0
--- /dev/null
+++ b/arch/powerpc/include/asm/qspinlock_paravirt_types.h
@@ -0,0 +1,13 @@
+#ifndef _ASM_QSPINLOCK_PARAVIRT_TYPES_H
+#define _ASM_QSPINLOCK_PARAVIRT_TYPES_H
+
+struct pv_lock_ops {
+ void (*lock)(struct qspinlock *lock, u32 val);
+ void (*unlock)(struct qspinlock *lock);
+ void (*wait)(u8 *ptr, u8 val, int cpu);
+ void (*kick)(int cpu);
+};
+
+extern struct pv_lock_ops pv_lock_op;
+
+#endif
diff --git a/arch/powerpc/kernel/paravirt.c b/arch/powerpc/kernel/paravirt.c
new file mode 100644
index 0000000..2e87fa6
--- /dev/null
+++ b/arch/powerpc/kernel/paravirt.c
@@ -0,0 +1,121 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/spinlock.h>
+#include <linux/smp.h>
+#include <linux/hash.h>
+#include <linux/bootmem.h>
+
+#define NUM_LOCK_CPU_ENTRY_SHIFT 16
+#define NUM_LOCK_CPU_ENTRY (1 << NUM_LOCK_CPU_ENTRY_SHIFT)
+#define NUM_LOCKS_PER_CPU 4
+
+static u16 *hash_lock_cpu_ptr;
+
+struct locks_on_cpu {
+ void *l[NUM_LOCKS_PER_CPU];
+ int count;
+};
+
+static DEFINE_PER_CPU(struct locks_on_cpu, node);
+
+static u16 *hash(void *l)
+{
+ int val = hash_ptr(l, NUM_LOCK_CPU_ENTRY_SHIFT);
+
+ return &hash_lock_cpu_ptr[val];
+}
+
+static void __init init_hash(void)
+{
+ int size = NUM_LOCK_CPU_ENTRY * sizeof(*hash_lock_cpu_ptr);
+
+ hash_lock_cpu_ptr = memblock_virt_alloc(size, 0);
+ memset(hash_lock_cpu_ptr, 0, size);
+}
+
+#define lock_get_holder(l) \
+ ((int)*hash(l) - 1)
+
+#define lock_set_holder(l) \
+ (*hash(l) = raw_smp_processor_id() + 1)
+
+static void *this_cpu_lock(void)
+{
+ struct locks_on_cpu *this_node = this_cpu_ptr(&node);
+ int i = this_node->count - 1;
+
+ return this_node->l[i];
+}
+
+static void cpu_save_lock(void *l)
+{
+ struct locks_on_cpu *this_node = this_cpu_ptr(&node);
+ int i = this_node->count++;
+
+ this_node->l[i] = l;
+}
+
+static void cpu_remove_lock(void *l)
+{
+ this_cpu_dec(node.count);
+}
+
+static void __native_queued_spin_unlock(struct qspinlock *lock)
+{
+ native_queued_spin_unlock(lock);
+}
+
+static void __pv_lock(struct qspinlock *lock, u32 val)
+{
+ cpu_save_lock(lock);
+ __pv_queued_spin_lock_slowpath(lock, val);
+ cpu_remove_lock(lock);
+ lock_set_holder(lock);
+}
+
+static void __pv_unlock(struct qspinlock *lock)
+{
+ __pv_queued_spin_unlock(lock);
+}
+
+static void __pv_wait(u8 *ptr, u8 val, int cpu)
+{
+ void *l = this_cpu_lock();
+
+ HMT_low();
+ while (READ_ONCE(*ptr) == val) {
+ cpu = lock_get_holder(l);
+ __spin_yield_cpu(cpu);
+ }
+ HMT_medium();
+}
+
+static void __pv_kick(int cpu)
+{
+ __spin_wake_cpu(cpu);
+}
+
+struct pv_lock_ops pv_lock_op = {
+ .lock = native_queued_spin_lock_slowpath,
+ .unlock = __native_queued_spin_unlock,
+ .wait = NULL,
+ .kick = NULL,
+};
+EXPORT_SYMBOL(pv_lock_op);
+
+void __init pv_lock_init(void)
+{
+ if (SHARED_PROCESSOR) {
+ init_hash();
+ __pv_init_lock_hash();
+ pv_lock_op.lock = __pv_lock;
+ pv_lock_op.unlock = __pv_unlock;
+ pv_lock_op.wait = __pv_wait;
+ pv_lock_op.kick = __pv_kick;
+ }
+}
diff --git a/arch/powerpc/platforms/pseries/setup.c b/arch/powerpc/platforms/pseries/setup.c
index 9883bc7..928b338 100644
--- a/arch/powerpc/platforms/pseries/setup.c
+++ b/arch/powerpc/platforms/pseries/setup.c
@@ -549,6 +549,11 @@ static void __init pSeries_setup_arch(void)
"%ld\n", rc);
}
}
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+ pv_lock_init();
+#endif
+
}
static int __init pSeries_init_panel(void)
--
2.4.11
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