Re: [Xen-devel] [PATCH] xen: arm: fully implement multicall interface.

[Julien Grall <julien.grall@xxxxxxxxxx>]

On 04/01/2014 11:49 AM, Ian Campbell wrote:
> On Tue, 2014-04-01 at 11:46 +0100, Julien Grall wrote:
>> On 04/01/2014 10:28 AM, Ian Campbell wrote:
>>> On Tue, 2014-04-01 at 10:05 +0100, Julien Grall wrote:
>>>> Out-of-context, I've noticed that most of trap failure will kill the 
>>>> domain. From the ARM ARM , if a coprocessor instruction is failing, we 
>>>> should     generate an Undefined Instruction exception (see P.7.5).
>>>
>>> You mean HSR_EC_CP15_32, HSR_EC_CP15_64 and HSR_EC_SYSREG?
>>>
>>> I've not checked but I think we only ask for traps for things which we
>>> are supposed to be able to handle, so anything which is trapped which we
>>> can't handle is a bug and would indicate the guest doing something
>>> funky.
>>
>> Right, but if the emulation of the instruction fails (see
>> vtimer_emulate, do_trap_psci,...), Xen will destroy the domain instead
>> of sending an UNDEF exception.
> 
> My point was that the emulation should never fail...

The emulation can fail if the guest decides to write on an RO register.

-- 
Julien Grall

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