The frame_list is an input, or an output, depending on whether the calling
domain is translated or not. The array does not need marshalling in both
directions.
Furthermore, the copy-in loop was very inefficient, copying 4 bytes at at
time. Rewrite it to copy in all nr_frames at once, and then expand
compat_pfn_t to xen_pfn_t in place.
Re-position the copy-in loop to simplify continuation support in a future
patch, and reduce the scope of certain variables.
No change in guest observed behaviour.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
Reviewed-by: Paul Durrant <p...@xen.org>
---
CC: George Dunlap <george.dun...@eu.citrix.com>
CC: Ian Jackson <i...@xenproject.org>
CC: Jan Beulich <jbeul...@suse.com>
CC: Stefano Stabellini <sstabell...@kernel.org>
CC: Wei Liu <w...@xen.org>
CC: Julien Grall <jul...@xen.org>
CC: Paul Durrant <p...@xen.org>
CC: Michał Leszczyński <michal.leszczyn...@cert.pl>
CC: Hubert Jasudowicz <hubert.jasudow...@cert.pl>
CC: Tamas K Lengyel <ta...@tklengyel.com>
---
xen/common/compat/memory.c | 65 ++++++++++++++++++++++++++++------------------
1 file changed, 40 insertions(+), 25 deletions(-)
diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c
index ed92e05b08..834c5e19d1 100644
--- a/xen/common/compat/memory.c
+++ b/xen/common/compat/memory.c
@@ -55,6 +55,8 @@ static int get_reserved_device_memory(xen_pfn_t start,
xen_ulong_t nr,
int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat)
{
+ struct vcpu *curr = current;
+ struct domain *currd = curr->domain;
int split, op = cmd & MEMOP_CMD_MASK;
long rc;
unsigned int start_extent = cmd >> MEMOP_EXTENT_SHIFT;
@@ -399,7 +401,7 @@ int compat_memory_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) compat)
case XENMEM_acquire_resource:
{
- xen_pfn_t *xen_frame_list;
+ xen_pfn_t *xen_frame_list = NULL;
unsigned int max_nr_frames;
if ( copy_from_guest(&cmp.mar, compat, 1) )
@@ -417,28 +419,10 @@ int compat_memory_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) compat)
if ( cmp.mar.nr_frames > max_nr_frames )
return -E2BIG;
- if ( compat_handle_is_null(cmp.mar.frame_list) )
- xen_frame_list = NULL;
- else
- {
+ /* Marshal the frame list in the remainder of the xlat space. */
+ if ( !compat_handle_is_null(cmp.mar.frame_list) )
xen_frame_list = (xen_pfn_t *)(nat.mar + 1);
- if ( !compat_handle_okay(cmp.mar.frame_list,
- cmp.mar.nr_frames) )
- return -EFAULT;
-
- for ( i = 0; i < cmp.mar.nr_frames; i++ )
- {
- compat_pfn_t frame;
-
- if ( __copy_from_compat_offset(
- &frame, cmp.mar.frame_list, i, 1) )
- return -EFAULT;
-
- xen_frame_list[i] = frame;
- }
- }
-
#define XLAT_mem_acquire_resource_HNDL_frame_list(_d_, _s_) \
set_xen_guest_handle((_d_)->frame_list, xen_frame_list)
@@ -446,6 +430,31 @@ int compat_memory_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) compat)
#undef XLAT_mem_acquire_resource_HNDL_frame_list
+ if ( xen_frame_list && cmp.mar.nr_frames )
+ {
+ /*
+ * frame_list is an input for translated guests, and an output
+ * for untranslated guests. Only copy in for translated
guests.
+ */
+ if ( paging_mode_translate(currd) )
+ {
+ compat_pfn_t *compat_frame_list = (void *)xen_frame_list;
+
+ if ( !compat_handle_okay(cmp.mar.frame_list,
+ cmp.mar.nr_frames) ||
+ __copy_from_compat_offset(
+ compat_frame_list, cmp.mar.frame_list,
+ 0, cmp.mar.nr_frames) )
+ return -EFAULT;
+
+ /*
+ * Iterate backwards over compat_frame_list[] expanding
+ * compat_pfn_t to xen_pfn_t in place.
+ */
+ for ( int x = cmp.mar.nr_frames - 1; x >= 0; --x )
+ xen_frame_list[x] = compat_frame_list[x];
+ }
+ }
break;
}
default:
@@ -590,8 +599,6 @@ int compat_memory_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) compat)
case XENMEM_acquire_resource:
{
- const xen_pfn_t *xen_frame_list = (xen_pfn_t *)(nat.mar + 1);
- compat_pfn_t *compat_frame_list = (compat_pfn_t *)(nat.mar + 1);
DEFINE_XEN_GUEST_HANDLE(compat_mem_acquire_resource_t);
if ( compat_handle_is_null(cmp.mar.frame_list) )
@@ -601,9 +608,18 @@ int compat_memory_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) compat)
compat_mem_acquire_resource_t),
nat.mar, nr_frames) )
return -EFAULT;
+ break;
}
- else
+
+ /*
+ * frame_list is an input for translated guests, and an output for
+ * untranslated guests. Only copy out for untranslated guests.
+ */
+ if ( !paging_mode_translate(currd) )
{
+ const xen_pfn_t *xen_frame_list = (xen_pfn_t *)(nat.mar + 1);
+ compat_pfn_t *compat_frame_list = (compat_pfn_t *)(nat.mar +
1);
+
/*
* NOTE: the smaller compat array overwrites the native
* array.
@@ -625,7 +641,6 @@ int compat_memory_op(unsigned int cmd,
XEN_GUEST_HANDLE_PARAM(void) compat)
cmp.mar.nr_frames) )
return -EFAULT;
}
-
break;
}
--
2.11.0
