[PATCH RESEND] x86, hyperv: bypass the timer_irq_works() check

[PATCH RESEND] x86, hyperv: bypass the timer_irq_works() check

[Jason Wang]

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.

Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: stable@vger.kernel.org
Acked-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 9f7ca26..832d05a 100644
--- 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_platform(void)
 
 	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 = {
-- 
1.8.3.2

RE: [PATCH RESEND] x86, hyperv: bypass the timer_irq_works() check

[KY Srinivasan]

> -----Original Message-----
> From: Jason Wang [mailto:jasowang@redhat.com]
> Sent: Thursday, February 27, 2014 7:30 PM
> To: KY Srinivasan; Haiyang Zhang; tglx@linutronix.de; mingo@redhat.com;
> hpa@zytor.com; x86@kernel.org; devel@linuxdriverproject.org; linux-
> kernel@vger.kernel.org
> Cc: Jason Wang; stable@vger.kernel.org
> Subject: [PATCH RESEND] x86, hyperv: bypass the timer_irq_works() check
> 
> 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.
> 
> Cc: K. Y. Srinivasan <kys@microsoft.com>
> Cc: Haiyang Zhang <haiyangz@microsoft.com>
> Cc: stable@vger.kernel.org
> Acked-by: K. Y. Srinivasan <kys@microsoft.com>
> Signed-off-by: Jason Wang <jasowang@redhat.com>
> ---
>  arch/x86/kernel/cpu/mshyperv.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c
> b/arch/x86/kernel/cpu/mshyperv.c index 9f7ca26..832d05a 100644
> --- 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_platform(void)
> 
>  	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 = {

Peter,

Please let us know if you have any issues with this patch.

Regards,

K. Y
> --
> 1.8.3.2

[tip:x86/hyperv] x86, hyperv: Bypass the timer_irq_works() check

[tip-bot for Jason Wang]

Commit-ID:  ca3ba2a2f4a49a308e7d78c784d51b2332064f15
Gitweb:     http://git.kernel.org/tip/ca3ba2a2f4a49a308e7d78c784d51b2332064f15
Author:     Jason Wang <jasowang@redhat.com>
AuthorDate: Fri, 28 Feb 2014 11:30:29 +0800
Committer:  H. Peter Anvin <hpa@linux.intel.com>
CommitDate: Thu, 27 Mar 2014 11:02:45 -0700

x86, hyperv: Bypass the timer_irq_works() check

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>
Cc: <stable@vger.kernel.org>
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>
---
 arch/x86/kernel/cpu/mshyperv.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 9f7ca26..832d05a 100644
--- 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_platform(void)
 
 	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 = {