[PATCH 3.13 03/32] x86, hyperv: Bypass the timer_irq_works() check

Greg Kroah-Hartman
2014-04-21T04:35:36Z

From: Jason Wang <jasowang@redhat.com>

commit ca3ba2a2f4a49a308e7d78c784d51b2332064f15 upstream.

This patch bypass the timer_irq_works() check for hyperv guest since:

- It was guaranteed to work.
- timer_irq_works() may fail sometime due to the lpj calibration were inaccurate
in a hyperv guest or a buggy host.

In the future, we should get the tsc frequency from hypervisor and use preset
lpj instead.

[ hpa: I would prefer to not defer things to "the future" in the future... ]

Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Link: http://lkml.kernel.org/r/1393558229-14755-1-git-send-email-jasowang@redhat.com
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
arch/x86/kernel/cpu/mshyperv.c | 6 ++++++
1 file changed, 6 insertions(+)

--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -26,6 +26,7 @@
#include <asm/irq_regs.h>
#include <asm/i8259.h>
#include <asm/apic.h>
+#include <asm/timer.h>

struct ms_hyperv_info ms_hyperv;
EXPORT_SYMBOL_GPL(ms_hyperv);
@@ -105,6 +106,11 @@ static void __init ms_hyperv_init_platfo

if (ms_hyperv.features & HV_X64_MSR_TIME_REF_COUNT_AVAILABLE)
clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
+
+#ifdef CONFIG_X86_IO_APIC
+ no_timer_check = 1;
+#endif
+
}

const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {