Messages in this thread | | | Subject | Re: [RFC PATCH 16/16] xen/grant-table: host_addr fixup in mapping on xenhost_r0 | From | Ankur Arora <> | Date | Tue, 18 Jun 2019 20:02:01 -0700 |
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On 6/17/19 3:55 AM, Juergen Gross wrote: > 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 <joao.m.martins@oracle.com> >> Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com> > > Without seeing the __xenbus_map_ring() modification it is impossible to > do a proper review of this patch. Will do in v2.
Ankur
> > > Juergen
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