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xen/granttable: Support transitive grants

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These allow a domain A which has been granted access on a page of domain B's
memory to issue domain C with a copy-grant on the same page.  This is useful
e.g. for forwarding packets between domains.

Signed-off-by: Annie Li <annie.li@oracle.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
This commit is contained in:
Annie Li 2011-12-12 18:15:07 +08:00 committed by Konrad Rzeszutek Wilk
parent 6666754b11
commit 9438ce9dbb
2 changed files with 82 additions and 0 deletions
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70
drivers/xen/grant-table.c
View file

@ -131,6 +131,18 @@ struct gnttab_ops {
void (*update_subpage_entry)(grant_ref_t ref, domid_t domid,
unsigned long frame, int flags,
unsigned page_off, unsigned length);
/*
* Redirect an available grant entry on domain A to another grant
* reference of domain B, then allow domain C to use grant reference
* of domain B transitively. Ref parameter is an available grant entry
* reference on domain A, domid is id of domain C which accesses grant
* entry transitively, flags is grant type and flag information,
* trans_domid is id of domain B whose grant entry is finally accessed
* transitively, trans_gref is grant entry transitive reference of
* domain B.
*/
void (*update_trans_entry)(grant_ref_t ref, domid_t domid, int flags,
domid_t trans_domid, grant_ref_t trans_gref);
};
static struct gnttab_ops *gnttab_interface;
@ -332,6 +344,63 @@ bool gnttab_subpage_grants_available(void)
}
EXPORT_SYMBOL_GPL(gnttab_subpage_grants_available);
void gnttab_update_trans_entry_v2(grant_ref_t ref, domid_t domid,
int flags, domid_t trans_domid,
grant_ref_t trans_gref)
{
gnttab_shared.v2[ref].transitive.trans_domid = trans_domid;
gnttab_shared.v2[ref].transitive.gref = trans_gref;
gnttab_shared.v2[ref].hdr.domid = domid;
wmb();
gnttab_shared.v2[ref].hdr.flags =
GTF_permit_access | GTF_transitive | flags;
}
int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
int flags, domid_t trans_domid,
grant_ref_t trans_gref)
{
if (flags & (GTF_accept_transfer | GTF_reading |
GTF_writing | GTF_sub_page))
return -EPERM;
if (gnttab_interface->update_trans_entry == NULL)
return -ENOSYS;
gnttab_interface->update_trans_entry(ref, domid, flags, trans_domid,
trans_gref);
return 0;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans_ref);
int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
domid_t trans_domid,
grant_ref_t trans_gref)
{
int ref, rc;
ref = get_free_entries(1);
if (unlikely(ref < 0))
return -ENOSPC;
rc = gnttab_grant_foreign_access_trans_ref(ref, domid, flags,
trans_domid, trans_gref);
if (rc < 0) {
put_free_entry(ref);
return rc;
}
return ref;
}
EXPORT_SYMBOL_GPL(gnttab_grant_foreign_access_trans);
bool gnttab_trans_grants_available(void)
{
return gnttab_interface->update_trans_entry != NULL;
}
EXPORT_SYMBOL_GPL(gnttab_trans_grants_available);
static int gnttab_query_foreign_access_v1(grant_ref_t ref)
{
return gnttab_shared.v1[ref].flags & (GTF_reading|GTF_writing);
@ -885,6 +954,7 @@ static struct gnttab_ops gnttab_v2_ops = {
.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,
.update_trans_entry = gnttab_update_trans_entry_v2,
};
static void gnttab_request_version(void)

12
include/xen/grant_table.h
View file

@ -65,6 +65,9 @@ int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
int flags, unsigned page_off,
unsigned length);
int gnttab_grant_foreign_access_trans(domid_t domid, int flags,
domid_t trans_domid,
grant_ref_t trans_gref);
/*
* Are sub-page grants available on this version of Xen? Returns true if they
@ -72,6 +75,12 @@ int gnttab_grant_foreign_access_subpage(domid_t domid, unsigned long frame,
*/
bool gnttab_subpage_grants_available(void);
/*
* Are transitive grants available on this version of Xen? Returns true if they
* are, and false if they're not.
*/
bool gnttab_trans_grants_available(void);
/*
* End access through the given grant reference, iff the grant entry is no
* longer in use. Return 1 if the grant entry was freed, 0 if it is still in
@ -121,6 +130,9 @@ int gnttab_grant_foreign_access_subpage_ref(grant_ref_t ref, domid_t domid,
unsigned long frame, int flags,
unsigned page_off,
unsigned length);
int gnttab_grant_foreign_access_trans_ref(grant_ref_t ref, domid_t domid,
int flags, domid_t trans_domid,
grant_ref_t trans_gref);
void gnttab_grant_foreign_transfer_ref(grant_ref_t, domid_t domid,
unsigned long pfn);