Re: [PATCH 1/6] iommu: Add new iommu op to get iommu hardware information

[Baolu Lu]

On 2023/2/13 10:36, Binbin Wu wrote:
> On 2/9/2023 12:16 PM, Yi Liu wrote:
> > From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> >
> > Introduce a new iommu op get
>
> get -> to get
>
>
> > the IOMMU hardware capabilities for iommufd.
> > This information will be used by any vIOMMU driver which is owned by
> > userspace.
> >
> > This op chooses to make the special parameters opaque to the core. This
> > suits the current usage model where accessing any of the IOMMU device
> > special parameters does require a userspace driver that matches the 
> > kernel
> > driver. If a need for common parameters, implemented similarly by several
> > drivers, arises then there is room in the design to grow a generic 
> > parameter
> > set as well. No warpper
>
> warpper -> wrapper

Thanks, will update.

> >   API is added as it is supposed to be used by
> > iommufd only.
> >
> > Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> > Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
> > Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx>
> > ---
> >   include/linux/iommu.h        | 8 ++++++++
> >   include/uapi/linux/iommufd.h | 6 ++++++
> >   2 files changed, 14 insertions(+)
> >
> > diff --git a/include/linux/iommu.h b/include/linux/iommu.h
> > index cb586d054c57..97b398d19fd2 100644
> > --- a/include/linux/iommu.h
> > +++ b/include/linux/iommu.h
> > @@ -15,6 +15,7 @@
> >   #include <linux/of.h>
> >   #include <linux/ioasid.h>
> >   #include <uapi/linux/iommu.h>
> > +#include <uapi/linux/iommufd.h>
> >   #define IOMMU_READ    (1 << 0)
> >   #define IOMMU_WRITE    (1 << 1)
> > @@ -223,6 +224,11 @@ struct iommu_iotlb_gather {
> >   /**
> >    * struct iommu_ops - iommu ops and capabilities
> >    * @capable: check capability
> > + * @hw_info: IOMMU hardware capabilities. The type of the returned 
> > data is
> > + *           defined in include/uapi/linux/iommufd.h. The data buffer is
> > + *           allocated in the IOMMU driver and the caller should free it
> > + *           after use. Return the data buffer if success, or ERR_PTR on
> > + *          failure.
> >    * @domain_alloc: allocate iommu domain
> >    * @probe_device: Add device to iommu driver handling
> >    * @release_device: Remove device from iommu driver handling
> > @@ -252,6 +258,7 @@ struct iommu_iotlb_gather {
> >    */
> >   struct iommu_ops {
> >       bool (*capable)(struct device *dev, enum iommu_cap);
> > +    void *(*hw_info)(struct device *dev, u32 *length);
> >       /* Domain allocation and freeing by the iommu driver */
> >       struct iommu_domain *(*domain_alloc)(unsigned iommu_domain_type);
> > @@ -280,6 +287,7 @@ struct iommu_ops {
> >       void (*remove_dev_pasid)(struct device *dev, ioasid_t pasid);
> >       const struct iommu_domain_ops *default_domain_ops;
> > +    enum iommu_device_data_type driver_type;
>
>
> How to understand the name "iommu_device_data_type"?

This is to tell userspace which type of IOMMU the returned information
comes from, Intel VT-d, ARM or others...

> Is it just refer to the driver types or it has a more generic meaning?

IOMMU driver sets this field to distinguish different IOMMU hardware.

Best regards,
baolu