x86: Hyper-V: Integrate the clocksource with Hyper-V detection code
The Hyper-V clocksource driver is best integrated with Hyper-V
detection code since:
(a) Linux guests running on Hyper-V require it
(b) Integration into that code significanly reduces code size
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Haiyang Zhang <haiyangz@microsoft.com>
Cc: gregkh@suse.de
Cc: devel@linuxdriverproject.org
Cc: virtualization@lists.osdl.org
Link: http://lkml.kernel.org/r/1315434310-4827-1-git-send-email-kys@microsoft.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index d944bf6..0a630dd 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -11,6 +11,8 @@
*/
#include <linux/types.h>
+#include <linux/time.h>
+#include <linux/clocksource.h>
#include <linux/module.h>
#include <asm/processor.h>
#include <asm/hypervisor.h>
@@ -36,6 +38,25 @@
!memcmp("Microsoft Hv", hyp_signature, 12);
}
+static cycle_t read_hv_clock(struct clocksource *arg)
+{
+ cycle_t current_tick;
+ /*
+ * Read the partition counter to get the current tick count. This count
+ * is set to 0 when the partition is created and is incremented in
+ * 100 nanosecond units.
+ */
+ rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+ return current_tick;
+}
+
+static struct clocksource hyperv_cs = {
+ .name = "hyperv_clocksource",
+ .rating = 400, /* use this when running on Hyperv*/
+ .read = read_hv_clock,
+ .mask = CLOCKSOURCE_MASK(64),
+};
+
static void __init ms_hyperv_init_platform(void)
{
/*
@@ -46,6 +67,8 @@
printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
ms_hyperv.features, ms_hyperv.hints);
+
+ clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
}
const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {