[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH V2 1/2] xen/granttable: Support sub-page grants
> -----Original Message----- > From: annie.li@xxxxxxxxxx [mailto:annie.li@xxxxxxxxxx] > Sent: 08 December 2011 09:37 > To: xen-devel@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; > konrad.wilk@xxxxxxxxxx; jeremy@xxxxxxxx; Paul Durrant; Ian Campbell > Cc: kurt.hackel@xxxxxxxxxx; annie.li@xxxxxxxxxx > Subject: [PATCH V2 1/2] xen/granttable: Support sub-page grants > > -- They can't be used to map the page (so can only be used in a > GNTTABOP_copy > hypercall). > -- It's possible to grant access with a finer granularity than > whole pages. > -- Xen guarantees that they can be revoked quickly (a normal map > grant can > only be revoked with the cooperation of the domain which has > been granted > access). > > Signed-off-by: Annie Li <annie.li@xxxxxxxxxx> > --- > drivers/xen/grant-table.c | 74 > +++++++++++++++++++++++++++++++++++++++++++++ > include/xen/grant_table.h | 13 ++++++++ > 2 files changed, 87 insertions(+), 0 deletions(-) > > diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c > index bd325fd..4a10e3f 100644 > --- a/drivers/xen/grant-table.c > +++ b/drivers/xen/grant-table.c > @@ -120,6 +120,16 @@ struct gnttab_ops { > * by bit operations. > */ > int (*query_foreign_access)(grant_ref_t); > + /* > + * Grant a domain to access a range of bytes within the page > referred by > + * an available grant entry. First parameter is grant entry > reference > + * number, second one is id of grantee domain, third one is > frame > + * address of subpage grant, forth one is grant type and flag > + * information, fifth one is offset of the range of bytes, > and last one > + * is length of bytes to be accessed. > + */ > + void (*update_subpage_entry)(grant_ref_t, domid_t, unsigned > long, int, > + unsigned, unsigned); > }; > > static struct gnttab_ops *gnttab_interface; @@ -261,6 +271,69 @@ > int gnttab_grant_foreign_access(domid_t domid, unsigned long frame, > } EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access); > > +void gnttab_update_subpage_entry_v2(grant_ref_t ref, domid_t domid, > + unsigned long frame, int flags, > + unsigned page_off, > + unsigned length) > +{ > + gnttab_shared.v2[ref].sub_page.frame = frame; > + gnttab_shared.v2[ref].sub_page.page_off = page_off; > + gnttab_shared.v2[ref].sub_page.length = length; > + gnttab_shared.v2[ref].hdr.domid = domid; > + wmb(); > + gnttab_shared.v2[ref].hdr.flags = > + GTF_permit_access | GTF_sub_page | > flags; } > + > +int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, > domid_t domid, > + unsigned long frame, int > flags, > + unsigned page_off, > + unsigned length) > +{ > + if (flags & (GTF_accept_transfer | GTF_reading | > + GTF_writing | GTF_transitive)) > + return -EPERM; > + > + if (gnttab_interface->update_subpage_entry == NULL) > + return -ENOSYS; > + > + gnttab_interface->update_subpage_entry(ref, domid, frame, > flags, > + page_off, length); > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage_ref); > + > +int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned > long frame, > + int flags, unsigned page_off, > + unsigned length) > +{ > + int ref; > + > + if (flags & (GTF_accept_transfer | GTF_reading | > + GTF_writing | GTF_transitive)) > + return -EPERM; > + > + if (gnttab_interface->update_subpage_entry == NULL) > + return -ENOSYS; > + > + ref = get_free_entries(1); > + if (unlikely(ref < 0)) > + return -ENOSPC; > + > + gnttab_interface->update_subpage_entry(ref, domid, frame, > flags, > + page_off, length); > + > + return ref; > +} > +EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage); There's quite a lot of duplicated code here. What about something along the lines of: #define get_free_entry() get_free_entries(1) int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame, int flags, unsigned page_off, unsigned length) { int ref; ref = get_free_entry(); if (unlikely(ref < 0)) return -ENOSPC; rc = gnttab_grant_foreign_access_subpage_ref(ref, domid, frame, flags, page_off, length); if (rc < 0) put_free_entry(ref); return (rc < 0) rc : ref; } EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_subpage); I think this is more akin to the format for existing non-ref variants. > + > +bool gnttab_subpage_grants_available(void) > +{ > + return gnttab_interface->update_subpage_entry != NULL; } > +EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available); > + > static int gnttab_query_foreign_access_v1(grant_ref_t ref) { > return gnttab_shared.v1[ref].flags & > (GTF_reading|GTF_writing); @@ -813,6 +886,7 @@ static struct > gnttab_ops gnttab_v2_ops = { > .end_foreign_access_ref = > gnttab_end_foreign_access_ref_v2, > .end_foreign_transfer_ref = > gnttab_end_foreign_transfer_ref_v2, > .query_foreign_access = > gnttab_query_foreign_access_v2, > + .update_subpage_entry = > gnttab_update_subpage_entry_v2, > }; > > static void gnttab_request_version(void) diff --git > a/include/xen/grant_table.h b/include/xen/grant_table.h index > fea4954..2b492b9 100644 > --- a/include/xen/grant_table.h > +++ b/include/xen/grant_table.h > @@ -62,6 +62,15 @@ int gnttab_resume(void); > > int gnttab_grant_foreign_access(domid_t domid, unsigned long frame, > int readonly); > +int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned > long frame, > + int flags, unsigned page_off, > + unsigned length); > + > +/* > + * Are sub-page grants available on this version of Xen? Returns > true > +if they > + * are, and false if they're not. > + */ > +bool gnttab_subpage_grants_available(void); > > /* > * End access through the given grant reference, iff the grant > entry is no @@ -108,6 +117,10 @@ void > gnttab_cancel_free_callback(struct gnttab_free_callback *callback); > > void gnttab_grant_foreign_access_ref(grant_ref_t ref, domid_t > domid, > unsigned long frame, int readonly); > +int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, > domid_t domid, > + unsigned long frame, int > flags, > + unsigned page_off, > + unsigned length); > > void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid, > unsigned long pfn); > -- > 1.7.6.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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