Hi Eric,
> From: Auger Eric <eric.auger@xxxxxxxxxx>
> Sent: Monday, July 6, 2020 9:22 PM
>
> 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
I see. will change it.
>
> >
> >>> + 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.
got you. do you think it is necessary to add your statement as a comment here?
Regards,
Yi Liu
> 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;
> >>> }
> >>>
> >
