Re: [PATCH] KEXEC: disable hpet legacy broadcasts earlier

[Keir Fraser <keir.xen@gmail.com>]

On 18/08/2011 14:31, "Andrew Cooper" <andrew.cooper3@citrix.com> wrote:

> On x2apic machines which booted in xapic mode,
> hpet_disable_legacy_broadcast() sends an event check IPI to all online
> processors.  This leads to a protection fault as the genapic blindly
> pokes x2apic MSRs while the local apic is in xapic mode.
> 
> One option is to change genapic when we shut down the local apic, but
> there are still problems with trying to IPI processors in the online
> processor map which are actually sitting in NMI loops
> 
> Another option is to have each CPU take itself out of the online CPU
> map during the NMI shootdown.
> 
> Realistically however, disabling hpet legacy broadcasts earlier in the
> kexec path is the easiest fix to the problem.

This for 4.1.2 as well I guess?

> Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
> 
> diff -r fc2be6cb89ad -r dcb3ed7b7dbd xen/arch/x86/crash.c
> --- a/xen/arch/x86/crash.c Tue Aug 16 15:05:55 2011 +0100
> +++ b/xen/arch/x86/crash.c Thu Aug 18 14:30:32 2011 +0100
> @@ -29,6 +29,7 @@
>  #include <asm/io_apic.h>
>  #include <xen/iommu.h>
>  #include <xen/pci.h>
> +#include <asm/hpet.h>
>  
>  static atomic_t waiting_for_crash_ipi;
>  static unsigned int crashing_cpu;
> @@ -61,6 +62,9 @@ static void nmi_shootdown_cpus(void)
>  
>      local_irq_disable();
>  
> +    if ( hpet_broadcast_is_available() )
> +        hpet_disable_legacy_broadcast();
> +
>      crashing_cpu = smp_processor_id();
>      local_irq_count(crashing_cpu) = 0;
>  
> diff -r fc2be6cb89ad -r dcb3ed7b7dbd xen/arch/x86/machine_kexec.c
> --- a/xen/arch/x86/machine_kexec.c Tue Aug 16 15:05:55 2011 +0100
> +++ b/xen/arch/x86/machine_kexec.c Thu Aug 18 14:30:32 2011 +0100
> @@ -85,9 +85,6 @@ void machine_kexec(xen_kexec_image_t *im
>          .limit = LAST_RESERVED_GDT_BYTE
>      };
>  
> -    if ( hpet_broadcast_is_available() )
> -        hpet_disable_legacy_broadcast();
> -
>      /* We are about to permenantly jump out of the Xen context into the kexec
>       * purgatory code.  We really dont want to be still servicing interupts.
>       */
> 
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