Re: [Xen-devel] [PATCH xen v2] xen: arm: fully implement multicall interface.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 08.04.14 at 13:18, <Ian.Campbell@xxxxxxxxxx> wrote:
> On Tue, 2014-04-08 at 08:13 +0100, Jan Beulich wrote:
>> But then again - is there anything wrong with actually carrying
>> out the multicall (with truncated arguments), resulting in the
>> domain dying only slightly later?
> 
> My concern was that this truncation happens naturally when running on a
> 32-bit hypervisor (since the actual hypercall implementations take
> 32-bit arguments internally). Meaning that the issue would be hidden
> until you move that kernel to a 64-bit hypervisor (with 64-bit hypercall
> arguments internally) at which point it mysteriously starts failing
> because some previously unnoticed garbage shows up in the top half of
> the argument.

Right - I understand all that. I wasn't suggesting to remove the
domain_crash(), just that by using the non-synchronous variant
you'd get the crash at the end of the multicall (or when it gets
preempted) instead of at the beginning. The effect to the guest
and programmer should be the same - the guest is dead and the
programmer (hopefully) goes looking for the problem.

Jan


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