@@ -727,7 +727,7 @@ __gnttab_map_grant_ref(
double_gt_lock(lgt, rgt);
- if ( gnttab_need_iommu_mapping(ld) )
+ if ( gnttab_need_iommu_mapping(ld) || is_domain_direct_mapped(ld) )
{
unsigned int wrc, rdc;
int err = 0;
@@ -738,13 +738,23 @@ __gnttab_map_grant_ref(
!(old_pin & (GNTPIN_hstw_mask|GNTPIN_devw_mask)) )
{
if ( wrc == 0 )
- err = iommu_map_page(ld, frame, frame,
- IOMMUF_readable|IOMMUF_writable);
+ {
+ if ( gnttab_need_iommu_mapping(ld) )
+ err = iommu_map_page(ld, frame, frame,
+ IOMMUF_readable|IOMMUF_writable);
+ else
+ err = arch_grant_map_page_identity(ld, frame, true);
+ }
}
else if ( act_pin && !old_pin )
{
if ( (wrc + rdc) == 0 )
- err = iommu_map_page(ld, frame, frame, IOMMUF_readable);
+ {
+ if ( gnttab_need_iommu_mapping(ld) )
+ err = iommu_map_page(ld, frame, frame, IOMMUF_readable);
+ else
+ err = arch_grant_map_page_identity(ld, frame, false);
+ }
}
if ( err )
{
@@ -935,15 +945,24 @@ __gnttab_unmap_common(
act->pin -= GNTPIN_hstw_inc;
}
- if ( gnttab_need_iommu_mapping(ld) )
+ if ( gnttab_need_iommu_mapping(ld) || is_domain_direct_mapped(ld) )
{
unsigned int wrc, rdc;
int err = 0;
mapcount(lgt, rd, op->frame, &wrc, &rdc);
if ( (wrc + rdc) == 0 )
- err = iommu_unmap_page(ld, op->frame);
- else if ( wrc == 0 )
- err = iommu_map_page(ld, op->frame, op->frame, IOMMUF_readable);
+ {
+ if ( gnttab_need_iommu_mapping(ld) )
+ err = iommu_unmap_page(ld, op->frame);
+ else
+ err = arch_grant_unmap_page_identity(ld, op->frame);
+ } else if ( wrc == 0 )
+ {
+ if ( gnttab_need_iommu_mapping(ld) )
+ err = iommu_map_page(ld, op->frame, op->frame, IOMMUF_readable);
+ else
+ err = arch_grant_map_page_identity(ld, op->frame, false);
+ }
if ( err )
{
rc = GNTST_general_error;
@@ -325,6 +325,8 @@ DO(xen_version)(int cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
break;
}
#endif
+ if ( is_domain_direct_mapped(d) )
+ fi.submap |= 1U << XENFEAT_grant_map_identity;
break;
default:
return -EINVAL;
@@ -94,6 +94,9 @@
/* 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__ */
The flag specifies that the hypervisor maps a grant page to guest physical address == machine address of the page in addition to the normal grant mapping address. Frontends are allowed to map the same page multiple times using multiple grant references. On the backend side it can be difficult to find out the physical address corresponding to a particular machine address, especially at the completation of a dma operation. To simplify address translations, we introduce a second mapping of the grant at physical address == machine address so that dom0 can issue cache maintenance operations without having to find the pfn. Call arch_grant_map_page_identity and arch_grant_unmap_page_identity from __gnttab_map_grant_ref and __gnttab_unmap_common to introduce the second mapping if the domain is directly mapped. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> --- Changes in v2: - rename XENFEAT_grant_map_11 to XENFEAT_grant_map_identity; - remove superfluous ifdef CONFIG_ARM in xen/common/kernel.c; - don't modify gnttab_need_iommu_mapping; - call arch_grant_map_page_identity and arch_grant_unmap_page_identity from grant_table functions. --- xen/common/grant_table.c | 35 +++++++++++++++++++++++++++-------- xen/common/kernel.c | 2 ++ xen/include/public/features.h | 3 +++ 3 files changed, 32 insertions(+), 8 deletions(-)