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x86: pvclock: generic pvclock vsyscall initialization
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Originally from Jeremy Fitzhardinge.

Introduce generic, non hypervisor specific, pvclock initialization
routines.

Signed-off-by: Marcelo Tosatti <[email protected]>
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matosatti committed Nov 28, 2012
1 parent 582b336 commit 71056ae
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Showing 4 changed files with 91 additions and 0 deletions.
1 change: 1 addition & 0 deletions arch/x86/include/asm/clocksource.h
Original file line number Diff line number Diff line change
Expand Up @@ -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 3 /* vDSO should use vread_pvclock. */

struct arch_clocksource_data {
int vclock_mode;
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5 changes: 5 additions & 0 deletions arch/x86/include/asm/fixmap.h
Original file line number Diff line number Diff line change
Expand Up @@ -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>
Expand Down Expand Up @@ -80,6 +81,10 @@ enum fixed_addresses {
+ ((VSYSCALL_END-VSYSCALL_START) >> PAGE_SHIFT) - 1,
VVAR_PAGE,
VSYSCALL_HPET,
#endif
#ifdef CONFIG_PARAVIRT_CLOCK
PVCLOCK_FIXMAP_BEGIN,
PVCLOCK_FIXMAP_END = PVCLOCK_FIXMAP_BEGIN+PVCLOCK_VSYSCALL_NR_PAGES-1,
#endif
FIX_DBGP_BASE,
FIX_EARLYCON_MEM_BASE,
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12 changes: 12 additions & 0 deletions arch/x86/include/asm/pvclock.h
Original file line number Diff line number Diff line change
Expand Up @@ -91,4 +91,16 @@ unsigned __pvclock_read_cycles(const struct pvclock_vcpu_time_info *src,
return version;
}

struct pvclock_vsyscall_time_info {
struct pvclock_vcpu_time_info pvti;
u32 migrate_count;
} __attribute__((__aligned__(SMP_CACHE_BYTES)));

#define PVTI_SIZE sizeof(struct pvclock_vsyscall_time_info)
#define PVCLOCK_VSYSCALL_NR_PAGES (((NR_CPUS-1)/(PAGE_SIZE/PVTI_SIZE))+1)

int __init pvclock_init_vsyscall(struct pvclock_vsyscall_time_info *i,
int size);
struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu);

#endif /* _ASM_X86_PVCLOCK_H */
73 changes: 73 additions & 0 deletions arch/x86/kernel/pvclock.c
Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,11 @@

#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/fixmap.h>
#include <asm/pvclock.h>

static u8 valid_flags __read_mostly = 0;
Expand Down Expand Up @@ -122,3 +127,71 @@ void pvclock_read_wallclock(struct pvclock_wall_clock *wall_clock,

set_normalized_timespec(ts, now.tv_sec, now.tv_nsec);
}

static struct pvclock_vsyscall_time_info *pvclock_vdso_info;

static struct pvclock_vsyscall_time_info *
pvclock_get_vsyscall_user_time_info(int cpu)
{
if (!pvclock_vdso_info) {
BUG();
return NULL;
}

return &pvclock_vdso_info[cpu];
}

struct pvclock_vcpu_time_info *pvclock_get_vsyscall_time_info(int cpu)
{
return &pvclock_get_vsyscall_user_time_info(cpu)->pvti;
}

#ifdef CONFIG_X86_64
static 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);

/* this is NULL when pvclock vsyscall is not initialized */
if (unlikely(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(struct pvclock_vsyscall_time_info *i,
int size)
{
int idx;

WARN_ON (size != PVCLOCK_VSYSCALL_NR_PAGES*PAGE_SIZE);

pvclock_vdso_info = i;

for (idx = 0; idx <= (PVCLOCK_FIXMAP_END-PVCLOCK_FIXMAP_BEGIN); idx++) {
__set_fixmap(PVCLOCK_FIXMAP_BEGIN + idx,
__pa_symbol(i) + (idx*PAGE_SIZE),
PAGE_KERNEL_VVAR);
}


register_task_migration_notifier(&pvclock_migrate);

return 0;
}
#endif

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