Please, apply patch both 3.10 and 3.9 Re: [PATCH 1/1] X86: Handle Xen emulation of Hyper-V more gracefully

[Victor Miasnikov]

Hi!


> > - /*
> > - * Xen emulates Hyper-V to support enlightened Windows.
> > - * Check to see first if we are on a Xen Hypervisor.
> > - */
> > - if (xen_cpuid_base())
> > - return false;

. . . 

> >  void hv_register_vmbus_handler(int irq, irq_handler_t handler)
> >  {
> > + /*
> > + * Setup the IDT for hypervisor callback.
> > + */
> > + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
> > +


Michael S. Tsirkin> Any chance we can fast-path this patch into 3.9 so 
Michael S. Tsirkin> that we don't release a kernel with hyper-v on Xen completely disabled?


Yes, this backport from linux-next ( future 3.10 ) to 3.9 ( on 2013-04-18 -- 3.9-rc(7+N) )  look like usefull . . .

Please, apply patch both 3.10 and 3.9

Best regards, Victor Miasnikov
Blog:  http://vvm.blog.tut.by/


----- Original Message ----- 
From: "Michael S. Tsirkin" 
To: "K. Y. Srinivasan"
Cc:
Sent: Thursday, April 18, 2013 5:17 PM
Subject: Re: [PATCH 1/1] X86: Handle Xen emulation of Hyper-V more gracefully


> On Thu, Apr 18, 2013 at 08:44:46AM -0700, K. Y. Srinivasan wrote:
> > Install the Hyper-V specific interrupt handler only when needed. This would
> > permit us to get rid of the Xen check. Note that when the vmbus drivers invokes
> > the call to register its handler, we are sure to be running on Hyper-V.
> >
> > Signed-off-by: K. Y. Srinivasan 
>
> Looks good to me, this will address the concern. FWIW
>
> Acked-by: Michael S. Tsirkin 
>
> Any chance we can fast-path this patch into 3.9 so that we don't release
> a kernel with hyper-v on Xen completely disabled?
>
> > ---

. . .
 
> > - /*
> > - * Xen emulates Hyper-V to support enlightened Windows.
> > - * Check to see first if we are on a Xen Hypervisor.
> > - */
> > - if (xen_cpuid_base())
> > - return false;
> > -
> >  cpuid(HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS,
> >        &eax, &hyp_signature[0], &hyp_signature[1], &hyp_signature[2]);
> >  
> > @@ -82,12 +75,6 @@ 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);
> > -#if IS_ENABLED(CONFIG_HYPERV)
> > - /*
> > - * Setup the IDT for hypervisor callback.
> > - */
> > - alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
> > -#endif
> >  }

. . .

> >  void hv_register_vmbus_handler(int irq, irq_handler_t handler)
> >  {
> > + /*
> > + * Setup the IDT for hypervisor callback.
> > + */
> > + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, hyperv_callback_vector);
> > +
> >  vmbus_irq = irq;

. . .

> >

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