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SubjectRe: [PATCH v2 01/16] iommu: introduce bind_pasid_table API function
On Tue, 10 Oct 2017 15:14:33 +0200
Joerg Roedel <joro@8bytes.org> wrote:

> Hi Jacob,
>
> On Thu, Oct 05, 2017 at 04:03:29PM -0700, Jacob Pan wrote:
> > +int iommu_unbind_pasid_table(struct iommu_domain *domain, struct
> > device *dev) +{
> > + if (unlikely(!domain->ops->unbind_pasid_table))
> > + return -EINVAL;
> > +
> > + return domain->ops->unbind_pasid_table(domain, dev);
> > +}
> > +EXPORT_SYMBOL_GPL(iommu_unbind_pasid_table);
>
> Are there other reasons to let the unbind fail? Otherwise I'd suggest
> to just make this a void function. Also not sure what the user of this
> function should do when the unbind really fails.
>
Agreed, void should do. There is no action for the callers.
> > +enum pasid_table_model {
> > + PASID_TABLE_FORMAT_HOST,
>
> What is this FORMAT_HOST for?
>
I was thinking it indicates whatever the host format is, if the guest
does not care.
> > + PASID_TABLE_FORMAT_ARM_1LVL,
> > + PASID_TABLE_FORMAT_ARM_2LVL,
> > + PASID_TABLE_FORMAT_AMD,
> > + PASID_TABLE_FORMAT_INTEL,
> > +};
> > +
> > +/**
> > + * PASID table data used to bind guest PASID table to the host
> > IOMMU. This will
> > + * enable guest managed first level page tables.
> > + * @version: for future extensions and identification of the data
> > format
> > + * @bytes: size of this structure
> > + * @base_ptr: PASID table pointer
> > + * @pasid_bits: number of bits supported in the guest PASID
> > table, must be less
> > + * or equal than the host table size.
> > + * @model: PASID table format for different IOMMU models
> > + */
> > +struct pasid_table_config {
> > + __u32 version;
>
> Can you also add a define for the version number? Userspace needs it
> to initialize the struct and the kernel to check against it.
>
Good point.
> > + __u32 bytes;
> > + __u64 base_ptr;
> > + __u8 pasid_bits;
> > + enum pasid_table_model model;
> > + union {
> > + struct {
> > + /* Intel specific fields */
> > + } intel;
> > +
> > + struct {
> > + /* ARM specific fields */
> > + bool pasid0_dma_no_pasid;
> > + } arm;
> > +
> > + struct {
> > + /* AMD specific fields */
> > + } amd;
>
> Thinking more about this, we can omit the sub-structs for models that
> don't need them. For the amd-model for example the base_ptr and
> pasid_bits fields are sufficient.
>
>
Sounds good, we can always add later and bump up the version. Intel does
not need model data for now.
> Regards,
>
> Joerg

[Jacob Pan]

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