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authorK. Y. Srinivasan2017-01-19 11:51:46 -0700
committerGreg Kroah-Hartman2017-01-20 14:48:03 +0100
commit63ed4e0c67df332681ebfef6eca6852da28d6300 (patch)
tree361afae5de4505521562d8a6ee6446dc9ce9fef5 /arch/x86/hyperv
parent669c256cb9fb29a540ce4befb4328d88c665e523 (diff)
Drivers: hv: vmbus: Consolidate all Hyper-V specific clocksource code
As part of the effort to separate out architecture specific code, consolidate all Hyper-V specific clocksource code to an architecture specific code. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/x86/hyperv')
-rw-r--r--arch/x86/hyperv/hv_init.c105
1 files changed, 105 insertions, 0 deletions
diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index b5c8e04deacb..860233af4568 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -24,6 +24,79 @@
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
+#include <linux/clockchips.h>
+
+
+#ifdef CONFIG_X86_64
+
+static struct ms_hyperv_tsc_page *tsc_pg;
+
+static u64 read_hv_clock_tsc(struct clocksource *arg)
+{
+ u64 current_tick;
+
+ if (tsc_pg->tsc_sequence != 0) {
+ /*
+ * Use the tsc page to compute the value.
+ */
+
+ while (1) {
+ u64 tmp;
+ u32 sequence = tsc_pg->tsc_sequence;
+ u64 cur_tsc;
+ u64 scale = tsc_pg->tsc_scale;
+ s64 offset = tsc_pg->tsc_offset;
+
+ rdtscll(cur_tsc);
+ /* current_tick = ((cur_tsc *scale) >> 64) + offset */
+ asm("mulq %3"
+ : "=d" (current_tick), "=a" (tmp)
+ : "a" (cur_tsc), "r" (scale));
+
+ current_tick += offset;
+ if (tsc_pg->tsc_sequence == sequence)
+ return current_tick;
+
+ if (tsc_pg->tsc_sequence != 0)
+ continue;
+ /*
+ * Fallback using MSR method.
+ */
+ break;
+ }
+ }
+ rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
+ return current_tick;
+}
+
+static struct clocksource hyperv_cs_tsc = {
+ .name = "hyperv_clocksource_tsc_page",
+ .rating = 400,
+ .read = read_hv_clock_tsc,
+ .mask = CLOCKSOURCE_MASK(64),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+#endif
+
+static u64 read_hv_clock_msr(struct clocksource *arg)
+{
+ u64 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_msr = {
+ .name = "hyperv_clocksource_msr",
+ .rating = 400,
+ .read = read_hv_clock_msr,
+ .mask = CLOCKSOURCE_MASK(64),
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
static void *hypercall_pg;
/*
@@ -31,6 +104,7 @@ static void *hypercall_pg;
* hypervisor has been detected.
*
* 1. Setup the hypercall page.
+ * 2. Register Hyper-V specific clocksource.
*/
void hyperv_init(void)
{
@@ -58,6 +132,37 @@ void hyperv_init(void)
hypercall_msr.enable = 1;
hypercall_msr.guest_physical_address = vmalloc_to_pfn(hypercall_pg);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+ /*
+ * Register Hyper-V specific clocksource.
+ */
+#ifdef CONFIG_X86_64
+ if (ms_hyperv.features & HV_X64_MSR_REFERENCE_TSC_AVAILABLE) {
+ union hv_x64_msr_hypercall_contents tsc_msr;
+
+ tsc_pg = __vmalloc(PAGE_SIZE, GFP_KERNEL, PAGE_KERNEL);
+ if (!tsc_pg) {
+ clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
+ return;
+ }
+
+ rdmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
+
+ tsc_msr.enable = 1;
+ tsc_msr.guest_physical_address = vmalloc_to_pfn(tsc_pg);
+
+ wrmsrl(HV_X64_MSR_REFERENCE_TSC, tsc_msr.as_uint64);
+ clocksource_register_hz(&hyperv_cs_tsc, NSEC_PER_SEC/100);
+ return;
+ }
+#endif
+ /*
+ * For 32 bit guests just use the MSR based mechanism for reading
+ * the partition counter.
+ */
+
+ if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
+ clocksource_register_hz(&hyperv_cs_msr, NSEC_PER_SEC/100);
}
/*