x86: pvclock: generic pvclock vsyscall initialization

Originally from Jeremy Fitzhardinge.

Introduce generic, non hypervisor specific, pvclock initialization
routines.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 73 insertions, 0 deletions

diff --git a/arch/x86/kernel/pvclock.c b/arch/x86/kernel/pvclock.c
index c8fb043a8695..85c39590c1a4 100644
--- a/arch/x86/kernel/pvclock.c
+++ b/arch/x86/kernel/pvclock.c
@@ -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;
@@ -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