On Wed, 27 Sep 2017 15:40:41 +0200
Joerg Roedel <[email protected]> wrote:
> Hi,
>
> On Wed, Sep 20, 2017 at 01:09:47PM +0100, Jean-Philippe Brucker wrote:
> > For binding page tables instead of PASID tables (e.g.
> > virtio-iommu), the generic data would be:
> >
> > struct pgtable_info {
> > __u32 pasid;
> > __u64 ptr;
> > __u32 model;
> > __u8 model_data[];
> > };
>
> I had a look again and at the AMD side there is no way to build a
> shadow pasid-table when more than 9-bit pasids are used, because all
> pointers in that multi-level table are GPA and thus translated.
>
> So how about allowing the virtio-iommu to build pasid-tables in
> different formats? We can easily collect the existing code for that in
> the Intel and AMD drivers into a library that could be used by the
> virtio-iommu driver too. Then the virtio-iommu can create the correct
> table for the host-iommu and we don't have to rely on shadowing.
>
> For binding whole pasid tables, reading through the thread, it looks
> like we can't get away with generic attributes that would fit
> everyone. For AMD and Intel it would suffice to have a base-ptr and
> the number of pasids-bits the table can map.
>
> The Intel driver can then calculate the size of the table and the AMD
> driver can compute the GLX value;
>
> In case we need the model-specific info, I'd like to have them
> explicitly stated in the struct:
>
> enum pasid_table_model {
> PASID_TABLE_INTEL,
> PASID_TABLE_ARM,
> PASID_TABLE_AMD,
> /* ... */
> };
>
I guess one vendor could have multiple pasid table format. so perhaps
the name could reflect the format as well?
> struct pasid_table_config {
> __u64 base_ptr;
> __u8 pasid_bits;
> union {
> struct {
> /* Intel specific fields */
> } intel;
>
> struct {
> /* ARM specific fields */
> } arm;
>
>
> struct {
> /* AMD specific fields */
> } amd;
>
> /* ... */
> };
> };
>
> How does that look?
>
It should work for us for now but I am not sure how stable the vendor
specific fields will be, this is UAPI. BTW, do you also intend to
include the pasid_table_model # in pasid_table_config?
> Regards,
>
> Joerg
>
[Jacob Pan]
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