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authorK. Y. Srinivasan <kys@microsoft.com>2011-09-07 15:25:10 -0700
committerThomas Gleixner <tglx@linutronix.de>2011-09-08 10:33:59 +0200
commit6f4151c89b7d036c755d8cf74729e09b76fa6676 (patch)
treec86026f4c56764596f5425892850f89cbc77ffb3 /arch/x86/kernel/cpu/mshyperv.c
parentddf28352b80c86754a6424e3a61e8bdf9213b3c7 (diff)
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>
Diffstat (limited to 'arch/x86/kernel/cpu/mshyperv.c')
-rw-r--r--arch/x86/kernel/cpu/mshyperv.c23
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index d944bf6c50e..0a630dd4b62 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 @@ static bool __init ms_hyperv_platform(void)
!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 @@ static void __init ms_hyperv_init_platform(void)
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 = {