Hi Yi,
On 7/6/20 2:46 PM, Liu, Yi L wrote:
> Hi Eric,
>
>> From: Auger Eric <eric.auger@xxxxxxxxxx>
>>
>> Hi Yi,
>>
>> Please add a commit message: instead of returning a boolean for
>> DOMAIN_ATTR_NESTING, arm_smmu_domain_get_attr() returns a
>> iommu_nesting_info handle.
>
> will do. thanks for the suggestion.
>
>>
>> On 7/4/20 1:26 PM, Liu Yi L wrote:
>>> Cc: Will Deacon <will@xxxxxxxxxx>
>>> Cc: Robin Murphy <robin.murphy@xxxxxxx>
>>> Cc: Eric Auger <eric.auger@xxxxxxxxxx>
>>> Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
>>> Suggested-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
>>> Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx>
>>> Signed-off-by: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx>
>>> ---
>>> drivers/iommu/arm-smmu-v3.c | 29 +++++++++++++++++++++++++++--
>>> drivers/iommu/arm-smmu.c | 29 +++++++++++++++++++++++++++--
>>> 2 files changed, 54 insertions(+), 4 deletions(-)
>>>
>>> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
>>> index f578677..0c45d4d 100644
>>> --- a/drivers/iommu/arm-smmu-v3.c
>>> +++ b/drivers/iommu/arm-smmu-v3.c
>>> @@ -3019,6 +3019,32 @@ static struct iommu_group
>> *arm_smmu_device_group(struct device *dev)
>>> return group;
>>> }
>>>
>>> +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain
>> *smmu_domain,
>>> + void *data)
>>> +{
>>> + struct iommu_nesting_info *info = (struct iommu_nesting_info *) data;
>>> + u32 size;
>>> +
>>> + if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
>>> + return -ENODEV;
>>> +
>>> + size = sizeof(struct iommu_nesting_info);
>>> +
>>> + /*
>>> + * if provided buffer size is not equal to the size, should
>>> + * return 0 and also the expected buffer size to caller.
>>> + */
>>> + if (info->size != size) {
>> < size?
>
> < size may work as well. but I'd like the caller provide exact buffer size. not sure
> if it is demand in kernel. do you have any suggestion?
I just suggested that by analogy with the VFIO argsz
>
>>> + info->size = size;
>>> + return 0;
>>> + }
>>> +
>>> + /* report an empty iommu_nesting_info for now */
>>> + memset(info, 0x0, size);
>>> + info->size = size;
>> For info, the current SMMU NESTED mode is not enabling any nesting. It just forces
>> the usage of the 2st stage instead of stage1 for single stage translation.
>
> yep. The intention is as below:
>
> " However it requires changing the get_attr(NESTING) implementations in both
> SMMU drivers as a precursor of this series, to avoid breaking
> VFIO_TYPE1_NESTING_IOMMU on Arm. Since we haven't yet defined the
> nesting_info structs for SMMUv2 and v3, I suppose we could return an empty
> struct iommu_nesting_info for now?"
> https://lore.kernel.org/linux-iommu/20200617143909.GA886590@myrica/
>
> do you think any other needs to be done for now?
I understand this is a prerequisite. It was more as an information.
Returning a void struct is a bit weird but at the moment I don't have
anything better.
Thanks
Eric
>
> Regards,
> Yi Liu
>
>> Thanks
>>
>> Eric
>>> + return 0;
>>> +}
>>> +
>>> static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
>>> enum iommu_attr attr, void *data) { @@ -
>> 3028,8 +3054,7 @@
>>> static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
>>> case IOMMU_DOMAIN_UNMANAGED:
>>> switch (attr) {
>>> case DOMAIN_ATTR_NESTING:
>>> - *(int *)data = (smmu_domain->stage ==
>> ARM_SMMU_DOMAIN_NESTED);
>>> - return 0;
>>> + return arm_smmu_domain_nesting_info(smmu_domain,
>> data);
>>> default:
>>> return -ENODEV;
>>> }
>>> diff --git a/drivers/iommu/arm-smmu.c b/drivers/iommu/arm-smmu.c index
>>> 243bc4c..908607d 100644
>>> --- a/drivers/iommu/arm-smmu.c
>>> +++ b/drivers/iommu/arm-smmu.c
>>> @@ -1506,6 +1506,32 @@ static struct iommu_group
>> *arm_smmu_device_group(struct device *dev)
>>> return group;
>>> }
>>>
>>> +static int arm_smmu_domain_nesting_info(struct arm_smmu_domain
>> *smmu_domain,
>>> + void *data)
>>> +{
>>> + struct iommu_nesting_info *info = (struct iommu_nesting_info *) data;
>>> + u32 size;
>>> +
>>> + if (!info || smmu_domain->stage != ARM_SMMU_DOMAIN_NESTED)
>>> + return -ENODEV;
>>> +
>>> + size = sizeof(struct iommu_nesting_info);
>>> +
>>> + /*
>>> + * if provided buffer size is not equal to the size, should
>>> + * return 0 and also the expected buffer size to caller.
>>> + */
>>> + if (info->size != size) {
>>> + info->size = size;
>>> + return 0;
>>> + }
>>> +
>>> + /* report an empty iommu_nesting_info for now */
>>> + memset(info, 0x0, size);
>>> + info->size = size;
>>> + return 0;
>>> +}
>>> +
>>> static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
>>> enum iommu_attr attr, void *data) { @@ -
>> 1515,8 +1541,7 @@
>>> static int arm_smmu_domain_get_attr(struct iommu_domain *domain,
>>> case IOMMU_DOMAIN_UNMANAGED:
>>> switch (attr) {
>>> case DOMAIN_ATTR_NESTING:
>>> - *(int *)data = (smmu_domain->stage ==
>> ARM_SMMU_DOMAIN_NESTED);
>>> - return 0;
>>> + return arm_smmu_domain_nesting_info(smmu_domain,
>> data);
>>> default:
>>> return -ENODEV;
>>> }
>>>
>
