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>

4 files changed, 91 insertions, 0 deletions

diff --git a/arch/x86/include/asm/clocksource.h b/arch/x86/include/asm/clocksource.h
index 0bdbbb3b9ce7..16a57f4ed64d 100644
--- a/arch/x86/include/asm/clocksource.h
+++ b/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 3 /* vDSO should use vread_pvclock. */
 
 struct arch_clocksource_data {
         int vclock_mode;
diff --git a/arch/x86/include/asm/fixmap.h b/arch/x86/include/asm/fixmap.h
index 4da3c0c4c974..a09c28571064 100644
--- a/arch/x86/include/asm/fixmap.h
+++ b/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
+        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
diff --git a/arch/x86/include/asm/pvclock.h b/arch/x86/include/asm/pvclock.h
index 63f91679af73..109a9dd5d454 100644
--- a/arch/x86/include/asm/pvclock.h
+++ b/arch/x86/include/asm/pvclock.h
@@ -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 */
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