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

From: KY Srinivasan
Date: Tue Mar 18 2014 - 08:39:44 EST




> -----Original Message-----
> From: Jason Wang [mailto:jasowang@xxxxxxxxxx]
> Sent: Thursday, February 27, 2014 7:30 PM
> To: KY Srinivasan; Haiyang Zhang; tglx@xxxxxxxxxxxxx; mingo@xxxxxxxxxx;
> hpa@xxxxxxxxx; x86@xxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-
> kernel@xxxxxxxxxxxxxxx
> Cc: Jason Wang; stable@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxxxxx>
> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx
> Acked-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> 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

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