Re: [Xen-devel] [PATCH v3 3/4] x86/smp: check APIC ID on AP bringup

[Jan Beulich <jbeulich@xxxxxxxx>]

On 04.12.2019 17:20, Roger Pau Monne wrote:
> Check that the processor to be woken up APIC ID is addressable in the
> current APIC mode.
> 
> Note that in practice systems with APIC IDs > 255 should already have
> x2APIC enabled by the firmware, and hence this is mostly a safety
> belt.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>

Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
with ...

> --- a/xen/arch/x86/smpboot.c
> +++ b/xen/arch/x86/smpboot.c
> @@ -1317,6 +1317,13 @@ int __cpu_up(unsigned int cpu)
>      if ( (apicid = x86_cpu_to_apicid[cpu]) == BAD_APICID )
>          return -ENODEV;
>  
> +    if ( (!x2apic_enabled || !iommu_intremap) && (apicid >> 8) )
> +    {
> +        printk("Unsupported: APIC ID %#x in xAPIC mode w/o interrupt 
> remapping",
> +               apicid);

... the lost newline added back (can be done while commiting).

Jan

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