Re: [Xen-devel] [PATCH for-4.11 v2 2/3] x86: guard against #NM

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 26.06.18 at 11:41, <andrew.cooper3@xxxxxxxxxx> wrote:
> On 26/06/18 07:36, Jan Beulich wrote:
>> --- a/xen/arch/x86/traps.c
>> +++ b/xen/arch/x86/traps.c
>> @@ -1749,7 +1749,21 @@ void do_device_not_available(struct cpu_
>>  {
>>      struct vcpu *curr = current;
>>  
>> -    BUG_ON(!guest_mode(regs));
>> +    if ( !guest_mode(regs) )
>> +    {
>> +        unsigned long fixup = search_exception_table(regs);
>> +
>> +        dprintk(XENLOG_ERR, "#NM: %p [%ps] -> %p\n",
> 
> gprintk() please.  the current vcpu is very likely relevant, and it
> would be extremely useful to see this line in release builds where it to
> happen.

Hmm, yes - it's different from other similar log messages then, but I can
see your point.

>> +                _p(regs->rip), _p(regs->rip), _p(fixup));
>> +        /*
>> +         * We mustn't come here, but for release builds have the recovery
> 
> "We shouldn't be able to reach here..."

Well, okay - I did consider this weaker wording, but had opted for the
stronger one then.

> Otherwise, Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Thanks.

Jan



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