[PATCH] powerpc/xmon: check before calling xive functions

[Cédric Le Goater]

On 10/19/2017 09:10 AM, Benjamin Herrenschmidt wrote:
> On Thu, 2017-10-19 at 00:02 +1100, Michael Ellerman wrote:
>> Breno Leitao <leitao at debian.org> writes:
>>
>>> Currently xmon could call XIVE functions from OPAL even if the XIVE is
>>> disabled or does not exist in the system, as in POWER8 machines.  This
>>> causes the following exception:
>>>
>>>  1:mon> dx
>>>  cpu 0x1: Vector: 700 (Program Check) at [c000000423c93450]
>>>      pc: c00000000009cfa4: opal_xive_dump+0x50/0x68
>>>      lr: c0000000000997b8: opal_return+0x0/0x50
>>>
>>> This patch simply checks if XIVE is enabled before calling XIVE
>>> functions.
>>
>> Thanks. I'll merge this.
>>
>> But we should also fix it in skiboot.
> 
> No that's wrong. xive_enabled() is only set if Linux is using native
> xive mode but some of those xmon functions dump the emulated state.
> 
> We should fix the actual cause of the crash.

which should be in the OPAL XIVE dump routines then ? 

Cheers 
C. 

> 
> Cheers,
> Ben.
> 
>> cheers
>>
>>> Suggested-by: Guilherme G. Piccoli <gpiccoli at linux.vnet.ibm.com>
>>> Signed-off-by: Breno Leitao <leitao at debian.org>
>>> ---
>>>  arch/powerpc/xmon/xmon.c | 6 ++++++
>>>  1 file changed, 6 insertions(+)
>>>
>>> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
>>> index 4679aeb84767..b34976c4a6ba 100644
>>> --- a/arch/powerpc/xmon/xmon.c
>>> +++ b/arch/powerpc/xmon/xmon.c
>>> @@ -2508,6 +2508,12 @@ static void dump_xives(void)
>>>  	unsigned long num;
>>>  	int c;
>>>  
>>> +	if (!xive_enabled()) {
>>> +		printf("Xive disabled on this system\n");
>>> +
>>> +		return;
>>> +	}
>>> +
>>>  	c = inchar();
>>>  	if (c == 'a') {
>>>  		dump_all_xives();
>>> -- 
>>> 2.14.2
>