Re: [patch 08/18] x86: pvclock: generic pvclock vsyscall initialization

2012-10-29 Thread Glauber Costa 
On 10/24/2012 05:13 PM, Marcelo Tosatti wrote:
 Index: vsyscall/arch/x86/Kconfig
 ===
 --- vsyscall.orig/arch/x86/Kconfig
 +++ vsyscall/arch/x86/Kconfig
 @@ -632,6 +632,13 @@ config PARAVIRT_SPINLOCKS
  
  config PARAVIRT_CLOCK
   bool
 +config PARAVIRT_CLOCK_VSYSCALL
 + bool Paravirt clock vsyscall support
 + depends on PARAVIRT_CLOCK  GENERIC_TIME_VSYSCALL
 + ---help---
 +   Enable performance critical clock related system calls to
 +   be executed in userspace, provided that the hypervisor
 +   supports it.
  
  endif

Besides debugging, what is the point in having this as an
extra-selectable? Is there any case in which a virtual machine has code
for this, but may decide to run without it ?

I believe all this code in vsyscall should be wrapped in PARAVIRT_CLOCK
only.
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Re: [patch 08/18] x86: pvclock: generic pvclock vsyscall initialization

2012-10-29 Thread Glauber Costa 
On 10/24/2012 05:13 PM, Marcelo Tosatti wrote:
 + */
 +int __init pvclock_init_vsyscall(void)
 +{
 + int idx;
 + unsigned int size = PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE;
 +
 + pvclock_vdso_info = __alloc_bootmem(size, PAGE_SIZE, 0);
 + if (!pvclock_vdso_info)
 + return -ENOMEM;
 +
 + memset(pvclock_vdso_info, 0, size);
 +
 + for (idx = 0; idx = (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
 + __set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
 +  __pa_symbol(pvclock_vdso_info) + (idx*PAGE_SIZE),
 +  PAGE_KERNEL_VVAR);


BTW, Previous line is whitespace damaged.

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Re: [patch 08/18] x86: pvclock: generic pvclock vsyscall initialization

2012-10-29 Thread Marcelo Tosatti 
On Mon, Oct 29, 2012 at 06:18:20PM +0400, Glauber Costa wrote:
 On 10/24/2012 05:13 PM, Marcelo Tosatti wrote:
  Index: vsyscall/arch/x86/Kconfig
  ===
  --- vsyscall.orig/arch/x86/Kconfig
  +++ vsyscall/arch/x86/Kconfig
  @@ -632,6 +632,13 @@ config PARAVIRT_SPINLOCKS
   
   config PARAVIRT_CLOCK
  bool
  +config PARAVIRT_CLOCK_VSYSCALL
  +   bool Paravirt clock vsyscall support
  +   depends on PARAVIRT_CLOCK  GENERIC_TIME_VSYSCALL
  +   ---help---
  + Enable performance critical clock related system calls to
  + be executed in userspace, provided that the hypervisor
  + supports it.
   
   endif
 
 Besides debugging, what is the point in having this as an
 extra-selectable? Is there any case in which a virtual machine has code
 for this, but may decide to run without it ?

Don't think so (its pretty small anyway, the code).

 I believe all this code in vsyscall should be wrapped in PARAVIRT_CLOCK
 only.

Unless Jeremy has a reason, i'm fine with that.

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Re: [patch 08/18] x86: pvclock: generic pvclock vsyscall initialization

2012-10-29 Thread Jeremy Fitzhardinge 
On 10/29/2012 07:54 AM, Marcelo Tosatti wrote:
 On Mon, Oct 29, 2012 at 06:18:20PM +0400, Glauber Costa wrote:
 On 10/24/2012 05:13 PM, Marcelo Tosatti wrote:
 Index: vsyscall/arch/x86/Kconfig
 ===
 --- vsyscall.orig/arch/x86/Kconfig
 +++ vsyscall/arch/x86/Kconfig
 @@ -632,6 +632,13 @@ config PARAVIRT_SPINLOCKS
  
  config PARAVIRT_CLOCK
 bool
 +config PARAVIRT_CLOCK_VSYSCALL
 +   bool Paravirt clock vsyscall support
 +   depends on PARAVIRT_CLOCK  GENERIC_TIME_VSYSCALL
 +   ---help---
 + Enable performance critical clock related system calls to
 + be executed in userspace, provided that the hypervisor
 + supports it.
  
  endif
 Besides debugging, what is the point in having this as an
 extra-selectable? Is there any case in which a virtual machine has code
 for this, but may decide to run without it ?
 Don't think so (its pretty small anyway, the code).

 I believe all this code in vsyscall should be wrapped in PARAVIRT_CLOCK
 only.
 Unless Jeremy has a reason, i'm fine with that.

I often set up blind config variables for dependency management; I'm
guessing the GENERIC_TIME_VSYSCALL dependency is important.  I think
the problem is that this exists, but that it's a user-selectable
option.  Removing the prompt should fix that.

J

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[patch 08/18] x86: pvclock: generic pvclock vsyscall initialization

2012-10-24 Thread Marcelo Tosatti 
Originally from Jeremy Fitzhardinge.

Introduce generic, non hypervisor specific, pvclock initialization 
routines.

Signed-off-by: Marcelo Tosatti mtosa...@redhat.com

Index: vsyscall/arch/x86/kernel/pvclock.c
===
--- vsyscall.orig/arch/x86/kernel/pvclock.c
+++ vsyscall/arch/x86/kernel/pvclock.c
@@ -17,6 +17,10 @@
 
 #include linux/kernel.h
 #include linux/percpu.h
+#include linux/notifier.h
+#include linux/sched.h
+#include linux/gfp.h
+#include linux/bootmem.h
 #include asm/pvclock.h
 
 static u8 valid_flags __read_mostly = 0;
@@ -122,3 +126,70 @@ void pvclock_read_wallclock(struct pvclo
 
set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
 }
+
+#ifdef CONFIG_PARAVIRT_CLOCK_VSYSCALL
+
+static aligned_pvti_t *pvclock_vdso_info;
+
+static struct pvclock_vsyscall_time_info 
*pvclock_get_vsyscall_user_time_info(int cpu)
+{
+   if (pvclock_vdso_info == NULL) {
+   BUG();
+   return NULL;
+   }
+
+   return pvclock_vdso_info[cpu].info;
+}
+
+struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu)
+{
+   return pvclock_get_vsyscall_user_time_info(cpu)-pvti;
+}
+
+int pvclock_task_migrate(struct notifier_block *nb, unsigned long l, void *v)
+{
+   struct task_migration_notifier *mn = v;
+   struct pvclock_vsyscall_time_info *pvti;
+
+   pvti = pvclock_get_vsyscall_user_time_info(mn-from_cpu);
+
+   if (pvti == NULL)
+   return NOTIFY_DONE;
+
+   pvti-migrate_count++;
+
+   return NOTIFY_DONE;
+}
+
+static struct notifier_block pvclock_migrate = {
+   .notifier_call = pvclock_task_migrate,
+};
+
+/*
+ * Initialize the generic pvclock vsyscall state.  This will allocate
+ * a/some page(s) for the per-vcpu pvclock information, set up a
+ * fixmap mapping for the page(s)
+ */
+int __init pvclock_init_vsyscall(void)
+{
+   int idx;
+   unsigned int size = PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE;
+
+   pvclock_vdso_info = __alloc_bootmem(size, PAGE_SIZE, 0);
+   if (!pvclock_vdso_info)
+   return -ENOMEM;
+
+   memset(pvclock_vdso_info, 0, size);
+
+   for (idx = 0; idx = (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
+   __set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
+__pa_symbol(pvclock_vdso_info) + (idx*PAGE_SIZE),
+PAGE_KERNEL_VVAR);
+   }
+
+   register_task_migration_notifier(pvclock_migrate);
+
+   return 0;
+}
+
+#endif /* CONFIG_PARAVIRT_CLOCK_VSYSCALL */
Index: vsyscall/arch/x86/include/asm/fixmap.h
===
--- vsyscall.orig/arch/x86/include/asm/fixmap.h
+++ vsyscall/arch/x86/include/asm/fixmap.h
@@ -19,6 +19,7 @@
 #include asm/acpi.h
 #include asm/apicdef.h
 #include asm/page.h
+#include asm/pvclock.h
 #ifdef CONFIG_X86_32
 #include linux/threads.h
 #include asm/kmap_types.h
@@ -81,6 +82,10 @@ enum fixed_addresses {
VVAR_PAGE,
VSYSCALL_HPET,
 #endif
+#ifdef CONFIG_PARAVIRT_CLOCK_VSYSCALL
+   PVCLOCK_FIXMAP_BEGIN,
+   PVCLOCK_FIXMAP_END = PVCLOCK_FIXMAP_BEGIN+PVCLOCK_VSYSCALL_NR_PAGES-1,
+#endif
FIX_DBGP_BASE,
FIX_EARLYCON_MEM_BASE,
 #ifdef CONFIG_PROVIDE_OHCI1394_DMA_INIT
Index: vsyscall/arch/x86/include/asm/pvclock.h
===
--- vsyscall.orig/arch/x86/include/asm/pvclock.h
+++ vsyscall/arch/x86/include/asm/pvclock.h
@@ -13,6 +13,8 @@ void pvclock_read_wallclock(struct pvclo
struct pvclock_vcpu_time_info *vcpu,
struct timespec *ts);
 void pvclock_resume(void);
+int __init pvclock_init_vsyscall(void);
+struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu);
 
 /*
  * Scale a 64-bit delta by scaling and multiplying by a 32-bit fraction,
@@ -85,4 +87,24 @@ unsigned __pvclock_read_cycles(const str
return version;
 }
 
+#ifdef CONFIG_PARAVIRT_CLOCK_VSYSCALL
+
+struct pvclock_vsyscall_time_info {
+   struct pvclock_vcpu_time_info pvti;
+   u32 migrate_count;
+};
+
+typedef union {
+   struct pvclock_vsyscall_time_info info;
+   char pad[SMP_CACHE_BYTES];
+} aligned_pvti_t cacheline_aligned;
+
+#define PVTI_SIZE sizeof(aligned_pvti_t)
+#if NR_CPUS == 1
+#define PVCLOCK_VSYSCALL_NR_PAGES 1
+#else
+#define PVCLOCK_VSYSCALL_NR_PAGES ((NR_CPUS-1)/(PAGE_SIZE/PVTI_SIZE))+1
+#endif
+#endif /* CONFIG_PARAVIRT_CLOCK_VSYSCALL */
+
 #endif /* _ASM_X86_PVCLOCK_H */
Index: vsyscall/arch/x86/include/asm/clocksource.h
===
--- vsyscall.orig/arch/x86/include/asm/clocksource.h
+++ vsyscall/arch/x86/include/asm/clocksource.h
@@ -8,6 +8,7 @@
 #define VCLOCK_NONE 0  /* No vDSO clock available. */
 #define VCLOCK_TSC  1  /* vDSO should use vread_tsc.   */
 #define VCLOCK_HPET 2  /* vDSO should use vread_hpet.  */
+#define VCLOCK_PVCLOCK