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xen/arm: introduce XENFEAT_grant_map_identity 

The flag tells us that the hypervisor maps a grant page to guest
physical address == machine address of the page in addition to the
normal grant mapping address. It is needed to properly issue cache
maintenance operation at the completion of a DMA operation involving a
foreign grant.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Tested-by: Denis Schneider <v1ne2go@gmail.com>
This commit is contained in:
Stefano Stabellini 2014-09-10 22:49:30 +00:00
parent 0b5a50635f
commit 5ebc77de83
2 changed files with 9 additions and 0 deletions
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6
arch/arm/xen/enlighten.c
View File

@ -260,6 +260,12 @@ static int __init xen_guest_init(void)
xen_domain_type = XEN_HVM_DOMAIN;
xen_setup_features();
if (!xen_feature(XENFEAT_grant_map_identity)) {
pr_warn("Please upgrade your Xen.\n"
"If your platform has any non-coherent DMA devices, they won't work properly.\n");
}
if (xen_feature(XENFEAT_dom0))
xen_start_info->flags |= SIF_INITDOMAIN|SIF_PRIVILEGED;
else

3
include/xen/interface/features.h
View File

@ -53,6 +53,9 @@
/* operation as Dom0 is supported */
#define XENFEAT_dom0 11
/* Xen also maps grant references at pfn = mfn */
#define XENFEAT_grant_map_identity 12
#define XENFEAT_NR_SUBMAPS 1
#endif /* __XEN_PUBLIC_FEATURES_H__ */