Re: [RFC for-4.5 06/12] xen/passthrough: rework dom0_pvh_reqs to use it also on ARM

[Julien Grall <julien.grall@linaro.org>]

On 02/10/2014 04:35 PM, Jan Beulich wrote:
>>>> On 10.02.14 at 17:10, Julien Grall <julien.grall@linaro.org> wrote:
>> On 02/07/2014 05:43 PM, Julien Grall wrote:
>>> DOM0 on ARM will have the same requirements as DOM0 PVH when iommu is 
>> enabled.
>>> Both PVH and ARM guest has paging mode translate enabled, so Xen can use it
>>> to know if it needs to check the requirements.
>>>
>>> Rename the function and remove "pvh" word in the commit message.
>>>
>>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>>> Cc: Xiantao Zhang <xiantao.zhang@intel.com>
>>> Cc: Jan Beulich <jbeulich@suse.com>
>>> ---
>>>  xen/drivers/passthrough/iommu.c |   14 +++++++++-----
>>>  1 file changed, 9 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
>>> index 19b0e23..26a5d91 100644
>>> --- a/xen/drivers/passthrough/iommu.c
>>> +++ b/xen/drivers/passthrough/iommu.c
>>> @@ -130,13 +130,18 @@ int iommu_domain_init(struct domain *d)
>>>      return hd->platform_ops->init(d);
>>>  }
>>>  
>>> -static __init void check_dom0_pvh_reqs(struct domain *d)
>>> +static __init void check_dom0_reqs(struct domain *d)
>>>  {
>>> +    if ( !paging_mode_translate(d) )
>>> +        return;
>>> +
>>>      if ( !iommu_enabled )
>>> -        panic("Presently, iommu must be enabled for pvh dom0\n");
>>> +        panic("Presently, iommu must be enabled to use dom0 with translate 
>> "
>>> +              "paging mode\n");
>>
>> Hmmm... this change is wrong. I forgot that iommu doesn't exist on some
>> ARM platform (for instance Arndale).
>>
>> Do we really this check for PVH? If yes, I will add replace the check
>> by: is_pvh_domain(d) && !iommu_enabled.
> 
> Of course we need it: How would PVH Dom0 be able to do any kind
> of DMA without an IOMMU?

Right, on ARM we have the 1:1 memory mapping to avoid this issue.

I will fix it. Can I keep your ack on this patch?

> Jan
> 


-- 
Julien Grall