Re: [PATCH RFC V9 16/19] kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor

2013-06-04 Thread Raghavendra K T 

On 06/03/2013 09:30 PM, Konrad Rzeszutek Wilk wrote:

On Sun, Jun 02, 2013 at 12:55:57AM +0530, Raghavendra K T wrote:

kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor

From: Srivatsa Vaddagiri va...@linux.vnet.ibm.com

During smp_boot_cpus  paravirtualied KVM guest detects if the hypervisor has
required feature (KVM_FEATURE_PV_UNHALT) to support pv-ticketlocks. If so,
  support for pv-ticketlocks is registered via pv_lock_ops.

Use KVM_HC_KICK_CPU hypercall to wakeup waiting/halted vcpu.

Signed-off-by: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
Signed-off-by: Suzuki Poulose suz...@in.ibm.com
[Raghu: check_zero race fix, enum for kvm_contention_stat
jumplabel related changes ]
Signed-off-by: Raghavendra K T raghavendra...@linux.vnet.ibm.com
---
  arch/x86/include/asm/kvm_para.h |   14 ++
  arch/x86/kernel/kvm.c   |  256 +++
  2 files changed, 268 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 695399f..427afcb 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -118,10 +118,20 @@ void kvm_async_pf_task_wait(u32 token);
  void kvm_async_pf_task_wake(u32 token);
  u32 kvm_read_and_reset_pf_reason(void);
  extern void kvm_disable_steal_time(void);
-#else
-#define kvm_guest_init() do { } while (0)
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+void __init kvm_spinlock_init(void);
+#else /* !CONFIG_PARAVIRT_SPINLOCKS */
+static inline void kvm_spinlock_init(void)
+{
+}
+#endif /* CONFIG_PARAVIRT_SPINLOCKS */
+
+#else /* CONFIG_KVM_GUEST */
+#define kvm_guest_init() do {} while (0)
  #define kvm_async_pf_task_wait(T) do {} while(0)
  #define kvm_async_pf_task_wake(T) do {} while(0)
+
  static inline u32 kvm_read_and_reset_pf_reason(void)
  {
return 0;
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index cd6d9a5..2715b92 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -34,6 +34,7 @@
  #include linux/sched.h
  #include linux/slab.h
  #include linux/kprobes.h
+#include linux/debugfs.h
  #include asm/timer.h
  #include asm/cpu.h
  #include asm/traps.h
@@ -419,6 +420,7 @@ static void __init kvm_smp_prepare_boot_cpu(void)
WARN_ON(kvm_register_clock(primary cpu clock));
kvm_guest_cpu_init();
native_smp_prepare_boot_cpu();
+   kvm_spinlock_init();
  }

  static void __cpuinit kvm_guest_cpu_online(void *dummy)
@@ -523,3 +525,257 @@ static __init int activate_jump_labels(void)
return 0;
  }
  arch_initcall(activate_jump_labels);
+
+/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
+void kvm_kick_cpu(int cpu)
+{
+   int apicid;
+
+   apicid = per_cpu(x86_cpu_to_apicid, cpu);
+   kvm_hypercall1(KVM_HC_KICK_CPU, apicid);
+}
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+
+enum kvm_contention_stat {
+   TAKEN_SLOW,
+   TAKEN_SLOW_PICKUP,
+   RELEASED_SLOW,
+   RELEASED_SLOW_KICKED,
+   NR_CONTENTION_STATS
+};
+
+#ifdef CONFIG_KVM_DEBUG_FS
+#define HISTO_BUCKETS  30
+
+static struct kvm_spinlock_stats
+{
+   u32 contention_stats[NR_CONTENTION_STATS];
+   u32 histo_spin_blocked[HISTO_BUCKETS+1];
+   u64 time_blocked;
+} spinlock_stats;
+
+static u8 zero_stats;
+
+static inline void check_zero(void)
+{
+   u8 ret;
+   u8 old;
+
+   old = ACCESS_ONCE(zero_stats);
+   if (unlikely(old)) {
+   ret = cmpxchg(zero_stats, old, 0);
+   /* This ensures only one fellow resets the stat */
+   if (ret == old)
+   memset(spinlock_stats, 0, sizeof(spinlock_stats));
+   }
+}
+
+static inline void add_stats(enum kvm_contention_stat var, u32 val)
+{
+   check_zero();
+   spinlock_stats.contention_stats[var] += val;
+}
+
+
+static inline u64 spin_time_start(void)
+{
+   return sched_clock();
+}
+
+static void __spin_time_accum(u64 delta, u32 *array)
+{
+   unsigned index;
+
+   index = ilog2(delta);
+   check_zero();
+
+   if (index  HISTO_BUCKETS)
+   array[index]++;
+   else
+   array[HISTO_BUCKETS]++;
+}
+
+static inline void spin_time_accum_blocked(u64 start)
+{
+   u32 delta;
+
+   delta = sched_clock() - start;
+   __spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
+   spinlock_stats.time_blocked += delta;
+}
+
+static struct dentry *d_spin_debug;
+static struct dentry *d_kvm_debug;
+
+struct dentry *kvm_init_debugfs(void)
+{
+   d_kvm_debug = debugfs_create_dir(kvm, NULL);
+   if (!d_kvm_debug)
+   printk(KERN_WARNING Could not create 'kvm' debugfs 
directory\n);
+
+   return d_kvm_debug;
+}
+
+static int __init kvm_spinlock_debugfs(void)
+{
+   struct dentry *d_kvm;
+
+   d_kvm = kvm_init_debugfs();
+   if (d_kvm == NULL)
+   return -ENOMEM;
+
+   d_spin_debug = debugfs_create_dir(spinlocks, d_kvm);
+
+   debugfs_create_u8(zero_stats, 0644,

Re: [PATCH RFC V9 16/19] kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor

2013-06-03 Thread Konrad Rzeszutek Wilk 
On Sun, Jun 02, 2013 at 12:55:57AM +0530, Raghavendra K T wrote:
 kvm : Paravirtual ticketlocks support for linux guests running on KVM 
 hypervisor
 
 From: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
 
 During smp_boot_cpus  paravirtualied KVM guest detects if the hypervisor has
 required feature (KVM_FEATURE_PV_UNHALT) to support pv-ticketlocks. If so,
  support for pv-ticketlocks is registered via pv_lock_ops.
 
 Use KVM_HC_KICK_CPU hypercall to wakeup waiting/halted vcpu.
 
 Signed-off-by: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
 Signed-off-by: Suzuki Poulose suz...@in.ibm.com
 [Raghu: check_zero race fix, enum for kvm_contention_stat
 jumplabel related changes ]
 Signed-off-by: Raghavendra K T raghavendra...@linux.vnet.ibm.com
 ---
  arch/x86/include/asm/kvm_para.h |   14 ++
  arch/x86/kernel/kvm.c   |  256 
 +++
  2 files changed, 268 insertions(+), 2 deletions(-)
 
 diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
 index 695399f..427afcb 100644
 --- a/arch/x86/include/asm/kvm_para.h
 +++ b/arch/x86/include/asm/kvm_para.h
 @@ -118,10 +118,20 @@ void kvm_async_pf_task_wait(u32 token);
  void kvm_async_pf_task_wake(u32 token);
  u32 kvm_read_and_reset_pf_reason(void);
  extern void kvm_disable_steal_time(void);
 -#else
 -#define kvm_guest_init() do { } while (0)
 +
 +#ifdef CONFIG_PARAVIRT_SPINLOCKS
 +void __init kvm_spinlock_init(void);
 +#else /* !CONFIG_PARAVIRT_SPINLOCKS */
 +static inline void kvm_spinlock_init(void)
 +{
 +}
 +#endif /* CONFIG_PARAVIRT_SPINLOCKS */
 +
 +#else /* CONFIG_KVM_GUEST */
 +#define kvm_guest_init() do {} while (0)
  #define kvm_async_pf_task_wait(T) do {} while(0)
  #define kvm_async_pf_task_wake(T) do {} while(0)
 +
  static inline u32 kvm_read_and_reset_pf_reason(void)
  {
   return 0;
 diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
 index cd6d9a5..2715b92 100644
 --- a/arch/x86/kernel/kvm.c
 +++ b/arch/x86/kernel/kvm.c
 @@ -34,6 +34,7 @@
  #include linux/sched.h
  #include linux/slab.h
  #include linux/kprobes.h
 +#include linux/debugfs.h
  #include asm/timer.h
  #include asm/cpu.h
  #include asm/traps.h
 @@ -419,6 +420,7 @@ static void __init kvm_smp_prepare_boot_cpu(void)
   WARN_ON(kvm_register_clock(primary cpu clock));
   kvm_guest_cpu_init();
   native_smp_prepare_boot_cpu();
 + kvm_spinlock_init();
  }
  
  static void __cpuinit kvm_guest_cpu_online(void *dummy)
 @@ -523,3 +525,257 @@ static __init int activate_jump_labels(void)
   return 0;
  }
  arch_initcall(activate_jump_labels);
 +
 +/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
 +void kvm_kick_cpu(int cpu)
 +{
 + int apicid;
 +
 + apicid = per_cpu(x86_cpu_to_apicid, cpu);
 + kvm_hypercall1(KVM_HC_KICK_CPU, apicid);
 +}
 +
 +#ifdef CONFIG_PARAVIRT_SPINLOCKS
 +
 +enum kvm_contention_stat {
 + TAKEN_SLOW,
 + TAKEN_SLOW_PICKUP,
 + RELEASED_SLOW,
 + RELEASED_SLOW_KICKED,
 + NR_CONTENTION_STATS
 +};
 +
 +#ifdef CONFIG_KVM_DEBUG_FS
 +#define HISTO_BUCKETS30
 +
 +static struct kvm_spinlock_stats
 +{
 + u32 contention_stats[NR_CONTENTION_STATS];
 + u32 histo_spin_blocked[HISTO_BUCKETS+1];
 + u64 time_blocked;
 +} spinlock_stats;
 +
 +static u8 zero_stats;
 +
 +static inline void check_zero(void)
 +{
 + u8 ret;
 + u8 old;
 +
 + old = ACCESS_ONCE(zero_stats);
 + if (unlikely(old)) {
 + ret = cmpxchg(zero_stats, old, 0);
 + /* This ensures only one fellow resets the stat */
 + if (ret == old)
 + memset(spinlock_stats, 0, sizeof(spinlock_stats));
 + }
 +}
 +
 +static inline void add_stats(enum kvm_contention_stat var, u32 val)
 +{
 + check_zero();
 + spinlock_stats.contention_stats[var] += val;
 +}
 +
 +
 +static inline u64 spin_time_start(void)
 +{
 + return sched_clock();
 +}
 +
 +static void __spin_time_accum(u64 delta, u32 *array)
 +{
 + unsigned index;
 +
 + index = ilog2(delta);
 + check_zero();
 +
 + if (index  HISTO_BUCKETS)
 + array[index]++;
 + else
 + array[HISTO_BUCKETS]++;
 +}
 +
 +static inline void spin_time_accum_blocked(u64 start)
 +{
 + u32 delta;
 +
 + delta = sched_clock() - start;
 + __spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
 + spinlock_stats.time_blocked += delta;
 +}
 +
 +static struct dentry *d_spin_debug;
 +static struct dentry *d_kvm_debug;
 +
 +struct dentry *kvm_init_debugfs(void)
 +{
 + d_kvm_debug = debugfs_create_dir(kvm, NULL);
 + if (!d_kvm_debug)
 + printk(KERN_WARNING Could not create 'kvm' debugfs 
 directory\n);
 +
 + return d_kvm_debug;
 +}
 +
 +static int __init kvm_spinlock_debugfs(void)
 +{
 + struct dentry *d_kvm;
 +
 + d_kvm = kvm_init_debugfs();
 + if (d_kvm == NULL)
 + return -ENOMEM;
 +
 + d_spin_debug = debugfs_create_dir(spinlocks, d_kvm);
 +
 +

[PATCH RFC V9 16/19] kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor

2013-06-01 Thread Raghavendra K T 
kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor

From: Srivatsa Vaddagiri va...@linux.vnet.ibm.com

During smp_boot_cpus  paravirtualied KVM guest detects if the hypervisor has
required feature (KVM_FEATURE_PV_UNHALT) to support pv-ticketlocks. If so,
 support for pv-ticketlocks is registered via pv_lock_ops.

Use KVM_HC_KICK_CPU hypercall to wakeup waiting/halted vcpu.

Signed-off-by: Srivatsa Vaddagiri va...@linux.vnet.ibm.com
Signed-off-by: Suzuki Poulose suz...@in.ibm.com
[Raghu: check_zero race fix, enum for kvm_contention_stat
jumplabel related changes ]
Signed-off-by: Raghavendra K T raghavendra...@linux.vnet.ibm.com
---
 arch/x86/include/asm/kvm_para.h |   14 ++
 arch/x86/kernel/kvm.c   |  256 +++
 2 files changed, 268 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 695399f..427afcb 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -118,10 +118,20 @@ void kvm_async_pf_task_wait(u32 token);
 void kvm_async_pf_task_wake(u32 token);
 u32 kvm_read_and_reset_pf_reason(void);
 extern void kvm_disable_steal_time(void);
-#else
-#define kvm_guest_init() do { } while (0)
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+void __init kvm_spinlock_init(void);
+#else /* !CONFIG_PARAVIRT_SPINLOCKS */
+static inline void kvm_spinlock_init(void)
+{
+}
+#endif /* CONFIG_PARAVIRT_SPINLOCKS */
+
+#else /* CONFIG_KVM_GUEST */
+#define kvm_guest_init() do {} while (0)
 #define kvm_async_pf_task_wait(T) do {} while(0)
 #define kvm_async_pf_task_wake(T) do {} while(0)
+
 static inline u32 kvm_read_and_reset_pf_reason(void)
 {
return 0;
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index cd6d9a5..2715b92 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -34,6 +34,7 @@
 #include linux/sched.h
 #include linux/slab.h
 #include linux/kprobes.h
+#include linux/debugfs.h
 #include asm/timer.h
 #include asm/cpu.h
 #include asm/traps.h
@@ -419,6 +420,7 @@ static void __init kvm_smp_prepare_boot_cpu(void)
WARN_ON(kvm_register_clock(primary cpu clock));
kvm_guest_cpu_init();
native_smp_prepare_boot_cpu();
+   kvm_spinlock_init();
 }
 
 static void __cpuinit kvm_guest_cpu_online(void *dummy)
@@ -523,3 +525,257 @@ static __init int activate_jump_labels(void)
return 0;
 }
 arch_initcall(activate_jump_labels);
+
+/* Kick a cpu by its apicid. Used to wake up a halted vcpu */
+void kvm_kick_cpu(int cpu)
+{
+   int apicid;
+
+   apicid = per_cpu(x86_cpu_to_apicid, cpu);
+   kvm_hypercall1(KVM_HC_KICK_CPU, apicid);
+}
+
+#ifdef CONFIG_PARAVIRT_SPINLOCKS
+
+enum kvm_contention_stat {
+   TAKEN_SLOW,
+   TAKEN_SLOW_PICKUP,
+   RELEASED_SLOW,
+   RELEASED_SLOW_KICKED,
+   NR_CONTENTION_STATS
+};
+
+#ifdef CONFIG_KVM_DEBUG_FS
+#define HISTO_BUCKETS  30
+
+static struct kvm_spinlock_stats
+{
+   u32 contention_stats[NR_CONTENTION_STATS];
+   u32 histo_spin_blocked[HISTO_BUCKETS+1];
+   u64 time_blocked;
+} spinlock_stats;
+
+static u8 zero_stats;
+
+static inline void check_zero(void)
+{
+   u8 ret;
+   u8 old;
+
+   old = ACCESS_ONCE(zero_stats);
+   if (unlikely(old)) {
+   ret = cmpxchg(zero_stats, old, 0);
+   /* This ensures only one fellow resets the stat */
+   if (ret == old)
+   memset(spinlock_stats, 0, sizeof(spinlock_stats));
+   }
+}
+
+static inline void add_stats(enum kvm_contention_stat var, u32 val)
+{
+   check_zero();
+   spinlock_stats.contention_stats[var] += val;
+}
+
+
+static inline u64 spin_time_start(void)
+{
+   return sched_clock();
+}
+
+static void __spin_time_accum(u64 delta, u32 *array)
+{
+   unsigned index;
+
+   index = ilog2(delta);
+   check_zero();
+
+   if (index  HISTO_BUCKETS)
+   array[index]++;
+   else
+   array[HISTO_BUCKETS]++;
+}
+
+static inline void spin_time_accum_blocked(u64 start)
+{
+   u32 delta;
+
+   delta = sched_clock() - start;
+   __spin_time_accum(delta, spinlock_stats.histo_spin_blocked);
+   spinlock_stats.time_blocked += delta;
+}
+
+static struct dentry *d_spin_debug;
+static struct dentry *d_kvm_debug;
+
+struct dentry *kvm_init_debugfs(void)
+{
+   d_kvm_debug = debugfs_create_dir(kvm, NULL);
+   if (!d_kvm_debug)
+   printk(KERN_WARNING Could not create 'kvm' debugfs 
directory\n);
+
+   return d_kvm_debug;
+}
+
+static int __init kvm_spinlock_debugfs(void)
+{
+   struct dentry *d_kvm;
+
+   d_kvm = kvm_init_debugfs();
+   if (d_kvm == NULL)
+   return -ENOMEM;
+
+   d_spin_debug = debugfs_create_dir(spinlocks, d_kvm);
+
+   debugfs_create_u8(zero_stats, 0644, d_spin_debug, zero_stats);
+
+   debugfs_create_u32(taken_slow, 0444, d_spin_debug,
+