Re: [Xen-devel] Xen-unstable: Bisected Host boot failure on AMD Phenom

[Sander Eikelenboom <linux@xxxxxxxxxxxxxx>]

On 02/03/17 15:55, Andrew Cooper wrote:
> On 02/03/17 14:42, Sander Eikelenboom wrote:
>> Hi Andrew / Jan,
>>
>> While testing current xen-unstable staging i ran into my host rebooting in 
>> early kernel boot. 
>> Bisection has turned up:
>>     5cecf60f439e828f4bc0d2a368ced9a73b130cb7 is the first bad commit
>>     Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
>>     Date:   Fri Feb 17 17:10:50 2017 +0000
>>
>>     x86/cpuid: Handle leaf 0x1 in guest_cpuid()
>>
>> Hardware is a AMD phenom x6.
>> Below is the output of serial console of a failed boot.
> 
> Hmm.  Sorry for breaking this (although my AMD servers are booting fine).

No problem, it is the staging branch of the unstable tree anyway ;-)

> It is unfortunately not entirely obvious what Linux is objecting to, and
> must be related to something visible in the emulated view.
> 
> Does this delta make any difference?

Yes it does, boots fine with this patch applied, thanks !

--
Sander

> 
> diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
> index 0dd35dc..c8fabe9 100644
> --- a/xen/arch/x86/cpuid.c
> +++ b/xen/arch/x86/cpuid.c
> @@ -747,9 +747,14 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
>          const struct cpu_user_regs *regs;
>  
>      case 0x1:
> -        /* TODO: Rework topology logic. */
> -        res->b &= 0x00ffffffu;
> -        res->b |= (v->vcpu_id * 2) << 24;
> +        if ( is_hardware_domain(d) )
> +            res->b = cpuid_ebx(0x1);
> +        else
> +        {
> +            /* TODO: Rework topology logic. */
> +            res->b &= 0x00ffffffu;
> +            res->b |= (v->vcpu_id * 2) << 24;
> +        }
>  
>          /* TODO: Rework vPMU control in terms of toolstack choices. */
>          if ( vpmu_available(v) &&
> 


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