On 09.05.19 19:25, Ankur Arora wrote:
Xenhost type xenhost_r0 does not support standard GNTTABOP_map_grant_ref semantics (map a gref onto a specified host_addr). That's because since the hypervisor is local (same address space as the caller of GNTTABOP_map_grant_ref), there is no external entity that could map an arbitrary page underneath an arbitrary address.To handle this, the GNTTABOP_map_grant_ref hypercall on xenhost_r0 treats the host_addr as an OUT parameter instead of IN and expects the gnttab_map_refs() and similar to fixup any state that caches the value of host_addr from before the hypercall. Accordingly gnttab_map_refs() now adds two parameters, a fixup function and a pointer to cached maps to fixup: int gnttab_map_refs(xenhost_t *xh, struct gnttab_map_grant_ref *map_ops, struct gnttab_map_grant_ref *kmap_ops, - struct page **pages, unsigned int count) + struct page **pages, gnttab_map_fixup_t map_fixup_fn, + void **map_fixup[], unsigned int count) The reason we use a fixup function and not an additional mapping op in the xenhost_t is because, depending on the caller, what we are fixing might be different: blkback, netback for instance cache host_addr in via a struct page *, while __xenbus_map_ring() caches a phys_addr. This patch fixes up xen-blkback and xen-gntdev drivers. TODO: - also rewrite gnttab_batch_map() and __xenbus_map_ring(). - modify xen-netback, scsiback, pciback etc Co-developed-by: Joao Martins <[email protected]> Signed-off-by: Ankur Arora <[email protected]>
Without seeing the __xenbus_map_ring() modification it is impossible to do a proper review of this patch. Juergen
