Re: [RFC 10/19] xen/passthrough: Introduce iommu_buildup

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

On 07/03/2014 12:45 PM, Ian Campbell wrote:
> On Mon, 2014-06-16 at 17:17 +0100, Julien Grall wrote:
>> This new function will correctly initialize the IOMMU page table for the
>> current domain.
> 
> _setup, _configure, _initialise, _construct etc would be more normal
> names I think.

I will rename to iommu_construct. The function is used to construct the
page table and set to 1 need_iommu(d).

> "buildup" is the half hour of mindless blather from pundits that you
> have to watch before a televised sporting event begins ;-)
> 
>> Also use it in iommu_assign_dt_device even though the current IOMMU
>> implementation on ARM shares P2M with the processor.
>> ---
>>  xen/drivers/passthrough/arm/iommu.c   |    6 ++++++
>>  xen/drivers/passthrough/device_tree.c |    7 +++++++
>>  xen/drivers/passthrough/iommu.c       |   25 +++++++++++++++++++++++++
>>  xen/drivers/passthrough/pci.c         |   12 ++++--------
>>  xen/include/xen/iommu.h               |    2 ++
>>  5 files changed, 44 insertions(+), 8 deletions(-)
>>
>> diff --git a/xen/drivers/passthrough/arm/iommu.c b/xen/drivers/passthrough/arm/iommu.c
>> index 3007b99..de4ed64 100644
>> --- a/xen/drivers/passthrough/arm/iommu.c
>> +++ b/xen/drivers/passthrough/arm/iommu.c
>> @@ -68,3 +68,9 @@ void arch_iommu_domain_destroy(struct domain *d)
>>  {
>>      iommu_dt_domain_destroy(d);
>>  }
>> +
>> +int arch_iommu_populate_page_table(struct domain *d)
>> +{
>> +    /* The IOMMU share the p2m with the CPU */
> 
> "shares"

Ok.

>> +    return -ENOSYS;
>> +}

[..]

>> +int iommu_buildup(struct domain *d)
> 
> Is there really not such a function already? How does x86 setup the
> iommu then?

There is a function to initialize the IOMMU but the activation and the
setup of page table are down later, I guess to avoid using memory for
nothing.

Regards,

-- 
Julien Grall