Re: [PATCH for 4.6 13/13] xen/iommu: smmu: Add Xen specific code to be able to use the driver

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

Hi Manish,

On 18/02/2015 01:02, Manish wrote:
>
> On 17/12/14 1:38 am, Julien Grall wrote:
>> The main goal is to modify as little the Linux code to be able to port
>> easily new feature added in Linux repo for the driver.
>>
>> To achieve that we:
>>      - Add helpers to Linux function not implemented on Xen
>>      - Add callbacks used by Xen to do our own stuff and call Linux ones
>>      - Only modify when required the code which comes from Linux. If so a
>>      comment has been added with /* Xen: ... */ explaining why it's
>>      necessary.
>>
>> The support for PCI has been commented because it's not yet supported by
>> Xen ARM and therefore won't compile.
>>
>> Signed-off-by: Julien Grall <julien.grall@linaro.org>
>> ---
>>   xen/drivers/passthrough/arm/Makefile |   1 +
>>   xen/drivers/passthrough/arm/smmu.c   | 668
>> +++++++++++++++++++++++++++++++----
>>   2 files changed, 602 insertions(+), 67 deletions(-)
>>
>> diff --git a/xen/drivers/passthrough/arm/Makefile
>> b/xen/drivers/passthrough/arm/Makefile
>> index 0484b79..f4cd26e 100644
>> --- a/xen/drivers/passthrough/arm/Makefile
>> +++ b/xen/drivers/passthrough/arm/Makefile
>> @@ -1 +1,2 @@
>>   obj-y += iommu.o
>> +obj-y += smmu.o
>> diff --git a/xen/drivers/passthrough/arm/smmu.c
>> b/xen/drivers/passthrough/arm/smmu.c
>> index 8a6514f..3cf1773 100644
>> --- a/xen/drivers/passthrough/arm/smmu.c
>> +++ b/xen/drivers/passthrough/arm/smmu.c
>> @@ -18,6 +18,13 @@
>>    *
>>    * Author: Will Deacon <will.deacon@arm.com>
>>    *
>> + * Based on Linux drivers/iommu/arm-smmu.c
>> + *    => commit e6b5be2be4e30037eb551e0ed09dd97bd00d85d3
>> + *
>> + * Xen modification:
>> + * Julien Grall <julien.grall@linaro.org>
>> + * Copyright (C) 2014 Linaro Limited.
>> + *
>>    * This driver currently supports:
>>    *    - SMMUv1 and v2 implementations
>>    *    - Stream-matching and stream-indexing
>> @@ -28,26 +35,154 @@
>>    *    - Context fault reporting
>>    */
>
> <<<snip >>>
>
>> +/* Xen: Dummy iommu_domain */
>> +struct iommu_domain
>> +{
>> +    struct arm_smmu_domain        *priv;
>> +
>> +    /* Used to link domain contexts for a same domain */
>> +    struct list_head        list;
>> +};
>> +
>> +/* Xen: Describes informations required for a Xen domain */
>> +struct arm_smmu_xen_domain {
>> +    spinlock_t            lock;
>> +    /* List of context (i.e iommu_domain) associated to this domain */
>> +    struct list_head        contexts;
>> +};
>> +
>> +/* Xen: Information about each device stored in dev->archdata.iommu */
>> +struct arm_smmu_xen_device {
>> +    struct iommu_domain *domain;
>> +    struct iommu_group *group;
>> +};
>> +
>> +#define dev_archdata(dev) ((struct arm_smmu_xen_device
>> *)dev->archdata.iommu)
>> +#define dev_iommu_domain(dev) (dev_archdata(dev)->domain)
>> +#define dev_iommu_group(dev) (dev_archdata(dev)->group)
>> +
>> +/* Xen: Dummy iommu_group */
>> +struct iommu_group
>> +{
>> +    struct arm_smmu_master_cfg *cfg;
>> +
>> +    atomic_t ref;
>> +};
>> +
> The naming needs to be revisited in this patch. Original driver from
> Will has arm_smmu_domain. This patch adds  iommu_domain,
> arm_smmu_xen_domain, iommu_group.

I can't change the naming of the structure. iommu_domain and iommu_group 
are from Linux. As we don't have it on Xen, I have to add dummy 
structure for it.

> Could you please add some description about the relation and hierarchy
> of these data structures.

Good point, I will try to add more comment and explain why we have to do it.

Regards,

-- 
Julien Grall