Re: [Xen-devel] [RFC 11/19] xen/passthrough: Call arch_iommu_domain_destroy before calling iommu_teardown

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.06.14 at 14:38, <julien.grall@xxxxxxxxxx> wrote:
> On 06/17/2014 10:29 AM, Jan Beulich wrote:
>>>>> On 17.06.14 at 11:18, <julien.grall@xxxxxxxxxx> wrote:
>>> On 17/06/14 09:07, Jan Beulich wrote:
>>>>>>> On 16.06.14 at 18:17, <julien.grall@xxxxxxxxxx> wrote:
>>>>> --- a/xen/drivers/passthrough/iommu.c
>>>>> +++ b/xen/drivers/passthrough/iommu.c
>>>>> @@ -219,10 +219,10 @@ void iommu_domain_destroy(struct domain *d)
>>>>>       if ( !iommu_enabled || !hd->platform_ops )
>>>>>           return;
>>>>>
>>>>> +    arch_iommu_domain_destroy(d);
>>>>> +
>>>>>       if ( need_iommu(d) )
>>>>>           iommu_teardown(d);
>>>>> -
>>>>> -    arch_iommu_domain_destroy(d);
>>>>
>>>> At the first glance this doesn't look right, including the explanation
>>>> you gave (why would devices still be assigned to a guest at this
>>>> point).
>>>
>>> Because the toolstack may forget to deassign a device. How do you handle 
>>> this case in x86? In the SMMU case, this will mean a memory leak and 
>>> misconfiguration of the registers.
>> 
>> Proper tool stack behavior is required (and not just here).
> 
> I think this is important to handle toolstack failure (such as crash)
> just in case. Hence it doesn't add much code for this purpose.

If you think this is necessary, then there's no reason to make this
ARM-specific (which in turn would eliminate the need for this to sit
in an arch hook).

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel