Tools: Memory sharing interface updates

tools/libxc/xc_memshr.c | 3 ++-

 tools/libxc/xenctrl.h   |  1 +
 2 files changed, 3 insertions(+), 1 deletions(-)

The libxc wrapper that shares two pages always assumed one of the pages was mapped by dom0. Expand the API to specify both sharing domains.

Signed-off-by Andres Lagar-Cavilla <[email protected]>

diff -r 835be7c121b7 -r 6f58de995103 tools/libxc/xc_memshr.c

tools/libxc/xc_memshr.c +1 -0

@@ -87,6 +87,7 @@ int xc_memshr_nominate_gref(xc_interface
 }
 
 int xc_memshr_share(xc_interface *xch,
+                    uint32_t source_domain,
                     uint64_t source_handle,
                     uint64_t client_handle)
 {

tools/libxc/xc_memshr.c +0 -0

     op = &(domctl.u.mem_sharing_op);
     op->op = XEN_DOMCTL_MEM_EVENT_OP_SHARING_SHARE;
     op->u.share.source_handle = source_handle;

diff -r 835be7c121b7 -r 6f58de995103 tools/libxc/xenctrl.h

tools/libxc/xenctrl.h +1 -0

@@ -1892,6 +1892,7 @@ int xc_memshr_nominate_gref(xc_interface
                             grant_ref_t gref,
                             uint64_t *handle);
 int xc_memshr_share(xc_interface *xch,
+                    uint32_t source_domain,
                     uint64_t source_handle,
                     uint64_t client_handle);
 int xc_memshr_domain_resume(xc_interface *xch,

tools/libxc/xc_memshr.c | 19 ++++++++++++++++++-

 tools/libxc/xenctrl.h   |   7 ++++++-
 2 files changed, 24 insertions(+), 2 deletions(-)

Previosuly, the mem sharing code would return an opaque handle to index shared pages (and nominees) in its global hash table. By removing the hash table, the handle becomes a version, to avoid sharing a stale version of a page. Thus, libxc wrappers need to be updated accordingly.

Signed-off-by Adin Scannell <[email protected]>

Signed-off-by Andres Lagar-Cavilla <[email protected]>

diff -r 6f58de995103 -r 892049dfc1c9 tools/libxc/xc_memshr.c

tools/libxc/xc_memshr.c +6 -1

@@ -88,8 +88,13 @@ int xc_memshr_nominate_gref(xc_interface
 
 int xc_memshr_share(xc_interface *xch,
                     uint32_t source_domain,
+                    uint64_t source_gfn,
                     uint64_t source_handle,
-                    uint64_t client_handle)
+                    int source_is_gref,
+                    uint32_t client_domain,
+                    uint64_t client_gfn,
+                    uint64_t client_handle,
+                    int client_is_gref)
 {
     DECLARE_DOMCTL;
     struct xen_domctl_mem_sharing_op *op;

tools/libxc/xc_memshr.c +9 -0

+                op->u.share.source_gfn, source_gfn);
+    else
+        op->u.share.source_gfn = source_gfn;
+    if (client_is_gref)
+        XEN_DOMCTL_MEM_SHARING_FIELD_MAKE_GREF(
+                op->u.share.client_gfn, client_gfn);
+    else
+        op->u.share.client_gfn = client_gfn;
+
     return do_domctl(xch, &domctl);
 }
 

diff -r 6f58de995103 -r 892049dfc1c9 tools/libxc/xenctrl.h

tools/libxc/xenctrl.h +6 -1

@@ -1893,8 +1893,13 @@ int xc_memshr_nominate_gref(xc_interface
                             uint64_t *handle);
 int xc_memshr_share(xc_interface *xch,
                     uint32_t source_domain,
+                    uint64_t source_gfn,
                     uint64_t source_handle,
-                    uint64_t client_handle);
+                    int source_is_gref,
+                    uint32_t client_domain,
+                    uint64_t client_gfn,
+                    uint64_t client_handle,
+                    int dest_is_gref);
 int xc_memshr_domain_resume(xc_interface *xch,
                             uint32_t domid);
 int xc_memshr_debug_gfn(xc_interface *xch,

tools/blktap2/drivers/Makefile | 2 +-

 tools/blktap2/drivers/tapdisk-image.c |   2 +-
 tools/blktap2/drivers/tapdisk-vbd.c   |   6 +++---
 tools/blktap2/drivers/tapdisk.h       |   6 +++++-
 tools/memshr/bidir-daemon.c           |  34 ++++++++++++++++++++++++----------
 tools/memshr/bidir-hash.h             |  13 ++++++++-----
 tools/memshr/interface.c              |  30 ++++++++++++++++++------------
 tools/memshr/memshr.h                 |  11 +++++++++--
 8 files changed, 69 insertions(+), 35 deletions(-)

The only (in-tree, that we know of) consumer of the mem sharing API is the memshr tool (conditionally linked into blktap2). Update it to use the new API.

tools/blktap2/drivers/tapdisk-image.c +0 -0

 #endif
        INIT_LIST_HEAD(&image->next);
 

diff -r 892049dfc1c9 -r e16f5d2643c9 tools/memshr/bidir-hash.h

tools/memshr/bidir-hash.h +3 -2

@@ -81,15 +81,16 @@ static int fgprtshr_mfn_cmp(uint32_t m1,
 #undef BIDIR_VALUE
 #undef BIDIR_KEY_T
 #undef BIDIR_VALUE_T
+
 /* TODO better hashes! */
 static inline uint32_t blockshr_block_hash(vbdblk_t block)
 {
     return (uint32_t)(block.sec) ^ (uint32_t)(block.disk_id);
 }
 
-static inline uint32_t blockshr_shrhnd_hash(uint64_t shrhnd)
+static inline uint32_t blockshr_shrhnd_hash(share_tuple_t shrhnd)
 {
-    return (uint32_t)shrhnd;
+    return ((uint32_t) shrhnd.handle);
 }
 
 static inline int blockshr_block_cmp(vbdblk_t b1, vbdblk_t b2)

tools/memshr/bidir-hash.h +1 -1

 }
 #define BIDIR_NAME_PREFIX       blockshr
 #define BIDIR_KEY               block
 #define BIDIR_VALUE             shrhnd
 #define BIDIR_KEY_T             vbdblk_t
-#define BIDIR_VALUE_T           uint64_t
+#define BIDIR_VALUE_T           share_tuple_t
 #include "bidir-namedefs.h"
 
 #endif /* BLOCK_MAP */

diff -r 892049dfc1c9 -r e16f5d2643c9 tools/memshr/interface.c

tools/memshr/interface.c +5 -4

@@ -145,16 +145,17 @@ void memshr_vbd_image_put(uint16_t memsh
 
 int memshr_vbd_issue_ro_request(char *buf,
                                 grant_ref_t gref,
-                                uint16_t file_id,
+                                uint16_t file_id,
                                 uint64_t sec,
                                 int secs,
-                                uint64_t *hnd)
+                                share_tuple_t *hnd)
 {
     vbdblk_t blk;
-    uint64_t s_hnd, c_hnd;
+    share_tuple_t source_st, client_st;
+    uint64_t c_hnd;
     int ret;
 
-    *hnd = 0;
+    *hnd = (share_tuple_t){ 0, 0, 0 };
     if(!vbd_info.enabled)
         return -1;
 

Quoted 13 lines

tools/blktap2/drivers/Makefile | 2 +-

 tools/blktap2/drivers/tapdisk-image.c |   2 +-
 tools/blktap2/drivers/tapdisk-vbd.c   |   6 +++---
 tools/blktap2/drivers/tapdisk.h       |   6 +++++-
 tools/memshr/bidir-daemon.c           |  34
++++++++++++++++++++++++----------
 tools/memshr/bidir-hash.h             |  13 ++++++++-----
 tools/memshr/interface.c              |  30
++++++++++++++++++------------
 tools/memshr/memshr.h                 |  11 +++++++++--
 8 files changed, 69 insertions(+), 35 deletions(-)

Quoted 3 lines

The only (in-tree, that we know of) consumer of the mem sharing API is the memshr tool (conditionally linked into blktap2). Update it to use the new API.

At least some of this must happen in the previous 2 patches so that the build is not broken.

Is there any benefit to conditionally linking this stuff? Is it lots of code or does it have some other undesirable impact when built even when it is quiescent? Seems like a recipe for bit rot to not build it, plus it makes it harder for people to consume via distro packages etc.

Quoted 12 lines

Signed-off-by Andres Lagar-Cavilla <[email protected]>

diff -r 892049dfc1c9 -r e16f5d2643c9 tools/blktap2/drivers/Makefile

tools/blktap2/drivers/Makefile +1 -1

@@ -43,7 +43,7 @@ MEMSHR_DIR = $(XEN_ROOT)/tools/memshr
 MEMSHRLIBS :=
 ifeq ($(CONFIG_Linux), __fixme__)
 CFLAGS += -DMEMSHR
-MEMSHRLIBS += $(MEMSHR_DIR)/libmemshr.a
+MEMSHRLIBS += -L$(XEN_ROOT)/tools/libxc -lxenctrl

Quoted 1 line

$(MEMSHR_DIR)/libmemshr.a

Please use $(LDLIBS_libxenctrl).

Is there a reason libmemshr is not a shared library?

tools/blktap2/drivers/tapdisk-image.c tapdisk_image_allocate(const char *file, · line 63

Quoted 13 lines

endif

ifeq ($(VHD_STATIC),y)
diff -r 892049dfc1c9 -r e16f5d2643c9
tools/blktap2/drivers/tapdisk-image.c

tools/blktap2/drivers/tapdisk-image.c +1 -1

@@ -60,7 +60,7 @@ tapdisk_image_allocate(const char *file,
        image->storage   = storage;
        image->private   = private;
 #ifdef MEMSHR
-       image->memshr_id = memshr_vbd_image_get(file);
+       image->memshr_id = memshr_vbd_image_get((char *)file);

Casting away the const here raises a big red flag. Why is this necessary? You should either fix the API of memshr_vbd_image_get or tapdisk_image_allocate IMHO and propagate the change as necessary. AFAICT there is no reason not to push the const'ness down into the memshr API.

Quoted 3 lines

tools/blktap2/drivers/tapdisk-image.c +0 -0

 #endif
        INIT_LIST_HEAD(&image->next);
 

[...]

Quoted 24 lines

diff -r 892049dfc1c9 -r e16f5d2643c9 tools/memshr/bidir-hash.h

tools/memshr/bidir-hash.h +3 -2

@@ -81,15 +81,16 @@ static int fgprtshr_mfn_cmp(uint32_t m1,
 #undef BIDIR_VALUE
 #undef BIDIR_KEY_T
 #undef BIDIR_VALUE_T
+
 /* TODO better hashes! */
 static inline uint32_t blockshr_block_hash(vbdblk_t block)
 {
     return (uint32_t)(block.sec) ^ (uint32_t)(block.disk_id);
 }
 
-static inline uint32_t blockshr_shrhnd_hash(uint64_t shrhnd)
+static inline uint32_t blockshr_shrhnd_hash(share_tuple_t shrhnd)
 {
-    return (uint32_t)shrhnd;
+    return ((uint32_t) shrhnd.handle);
 }
 
 static inline int blockshr_block_cmp(vbdblk_t b1, vbdblk_t b2)

@@ -97,15 +98,17 @@ static inline int blockshr_block_cmp(vbd
     return (b1.sec == b2.sec) && (b1.disk_id == b2.disk_id);

tools/memshr/bidir-hash.h static inline int blockshr_block_cmp(vbd · line 106

Quoted 10 lines

tools/memshr/bidir-hash.h +4 -2

 }
 
-static inline int blockshr_shrhnd_cmp(uint64_t h1, uint64_t h2)
+static inline int blockshr_shrhnd_cmp(share_tuple_t h1, share_tuple_t
 h2)
 {
-    return (h1 == h2);
+    return ( (h1.domain == h2.domain) &&
+             (h1.frame  == h2.frame) &&
+             (h1.handle == h2.handle) );

memcmp?

Quoted 40 lines

tools/memshr/bidir-hash.h +1 -1

 }
 #define BIDIR_NAME_PREFIX       blockshr
 #define BIDIR_KEY               block
 #define BIDIR_VALUE             shrhnd
 #define BIDIR_KEY_T             vbdblk_t
-#define BIDIR_VALUE_T           uint64_t
+#define BIDIR_VALUE_T           share_tuple_t
 #include "bidir-namedefs.h"
 

#endif /* BLOCK_MAP */
diff -r 892049dfc1c9 -r e16f5d2643c9 tools/memshr/interface.c

tools/memshr/interface.c +5 -4

@@ -145,16 +145,17 @@ void memshr_vbd_image_put(uint16_t memsh
 
 int memshr_vbd_issue_ro_request(char *buf,
                                 grant_ref_t gref,
-                                uint16_t file_id,
+                                uint16_t file_id,
                                 uint64_t sec,
                                 int secs,
-                                uint64_t *hnd)
+                                share_tuple_t *hnd)
 {
     vbdblk_t blk;
-    uint64_t s_hnd, c_hnd;
+    share_tuple_t source_st, client_st;
+    uint64_t c_hnd;
     int ret;
 
-    *hnd = 0;
+    *hnd = (share_tuple_t){ 0, 0, 0 };
     if(!vbd_info.enabled)
         return -1;
 

@@ -169,26 +170,31 @@ int memshr_vbd_issue_ro_request(char *bu
     /* If page couldn't be made sharable, we cannot do anything about

it */

     if(ret != 0)
         return -3;

tools/memshr/interface.c int memshr_vbd_issue_ro_request(char *bu · line 174

Quoted 3 lines

tools/memshr/interface.c +2 -1

-    *hnd = c_hnd;
+
+    *(&client_st) = (share_tuple_t){ vbd_info.domid, gref, c_hnd };

Is "*(&thing)" somehow different to "thing"?

Quoted 10 lines

tools/memshr/interface.c +3 -2

+    *hnd = client_st;
 
     /* Check if we've read matching disk block previously */
     blk.sec     = sec;
     blk.disk_id = file_id;
-    if(blockshr_block_lookup(memshr.blks, blk, &s_hnd) > 0)
+    if(blockshr_block_lookup(memshr.blks, blk, &source_st) > 0)
     {
-        ret = xc_memshr_share(vbd_info.xc_handle, s_hnd, c_hnd);
+        ret = xc_memshr_share(vbd_info.xc_handle, source_st.domain,

Quoted 3 lines

source_st.frame,
+ source_st.handle, 1, vbd_info.domid,
gref, c_hnd, 1);

These 1's == is a gref but I only know that because I was just reading that patch. If you decide you do need to keep the flag separate then this would be better as a flags argument with named values XC_MEMSHR_SOURCE_IS_GREF etc.

tools/memshr/memshr.h line 33

Quoted 13 lines

diff -r 892049dfc1c9 -r e16f5d2643c9 tools/memshr/memshr.h

tools/memshr/memshr.h +6 -0

@@ -25,6 +25,13 @@
 
 typedef uint64_t xen_mfn_t;
 
+typedef struct share_tuple
+{
+    uint32_t domain;
+    uint64_t frame;
+    uint64_t handle;
+} share_tuple_t;

Didn't you just add these as three separate parameters to xc_memshr_share? Seems like this could be xc_memshr_tuple (or some better name with more meaning than "tuple") and used throughout.

Ian.

docs/man/xl.pod.1 | 18 +++++++++

 tools/libxl/xl.h          |   1 +
 tools/libxl/xl_cmdimpl.c  |  85 +++++++++++++++++++++++++++++++++++++++++++++++
 tools/libxl/xl_cmdtable.c |   6 +++
 4 files changed, 110 insertions(+), 0 deletions(-)

Signed-off-by Andres Lagar-Cavilla <[email protected]>

Signed-off-by Adin Scannell <[email protected]>

diff -r e16f5d2643c9 -r a22140d92931 docs/man/xl.pod.1

docs/man/xl.pod.1 +1 -0

@@ -280,6 +280,24 @@ B<Warning:> There is no good way to know
 mem-set will make a domain unstable and cause it to crash.  Be very
 careful when using this command on running domains.
 
+=item B<sharing> [I<-t> I<--totals>] [I<domain-id>]

=item B<migrate> [I<OPTIONS>] I<domain-id> I<host>

diff -r e16f5d2643c9 -r a22140d92931 tools/libxl/xl_cmdimpl.c

tools/libxl/xl_cmdimpl.c +0 -0

@@ -3755,6 +3755,91 @@ int main_info(int argc, char **argv)

tools/libxl/xl_cmdimpl.c +6 -0

+int main_sharing(int argc, char **argv)
+{
+    int opt;
+    int option_index = 0;
+    static struct option long_options[] = {
+        {"help", 0, 0, 'h'},

tools/libxc/xc_private.c | 10 ++++++++++

 tools/libxc/xenctrl.h    |   4 ++++
 2 files changed, 14 insertions(+), 0 deletions(-)

Signed-off-by Adin Scannell <[email protected]>

tools/libxc/xenctrl.h +1 -0

+
 /* Get current total pages allocated to a domain. */
 long xc_get_tot_pages(xc_interface *xch, uint32_t domid);
 

Quoted 6 lines

tools/libxc/xc_private.c | 10 ++++++++++

 tools/libxc/xenctrl.h    |   4 ++++
 2 files changed, 14 insertions(+), 0 deletions(-)

Signed-off-by Adin Scannell <[email protected]>

If you pass on someone elses work I think it is normal to add your own Signed-off-by (per DCO clause (c)).

[...]

Quoted 7 lines

diff -r a22140d92931 -r 6e8b8fb2c8b2 tools/libxc/xenctrl.h

tools/libxc/xenctrl.h +0 -0

@@ -1227,6 +1227,10 @@ int xc_mmuext_op(xc_interface *xch, stru
 /* System wide memory properties */
 long xc_maximum_ram_page(xc_interface *xch);
 

tools/libxc/xenctrl.h int xc_mmuext_op(xc_interface *xch, stru · line 1232

Quoted 3 lines

tools/libxc/xenctrl.h +3 -0

+long xc_sharing_freed_pages(xc_interface *xch);
+
+long xc_sharing_used_frames(xc_interface *xch);

A quick comment on what each function returns might be worthwhile, maybe it's obvious to someone who knows the sharing stuff, but e.g. does "used" mean used right now or does it mean have ever been used? I suppose "freed" must be historical.

Also why pages vs frames? The underlying domctl is always pages.

Ian.

Quoted 4 lines

tools/libxc/xenctrl.h +1 -0

+
 /* Get current total pages allocated to a domain. */
 long xc_get_tot_pages(xc_interface *xch, uint32_t domid);
 

used_frames indicates the number of frames of memory that are shared, each, by two or more domains. We use the term "frame" because it's commonly used in textbooks for MMUs, in the sense that "a frame hosts a page" or "a page maps to a frame". Thus our use of shared frames, representing a different page (albeit with identical contents) to different domains.

freed_pages indicates the number of individual pages freed as a result of sharing. These are pages, one per domain.

Quoted 6 lines · Andres Lagar-Cavilla

used_frames indicates the number of frames of memory that are shared, each, by two or more domains. We use the term "frame" because it's commonly used in textbooks for MMUs, in the sense that "a frame hosts a page" or "a page maps to a frame". Thus our use of shared frames, representing a different page (albeit with identical contents) to different domains.

As Andres has pointed out, I named it frames to clearly differentiate it from other page-based domctls (it worked!). With the unusual condition of multiple domains pointing to the same frame, the nomenclature gets a bit hairy. Any suggestions on this front?

Quoted 2 lines

freed_pages indicates the number of individual pages freed as a result of sharing. These are pages, one per domain.

Here's a quick explanation and reason for these stats:

The way I see it, there are three easy-to-track, non-historical stats about sharing.
X - The total number of domain pages that map to shared frames. Y - The number of frames saved with sharing.
Z - The total number of shared frames (i.e. pages owned by dom_cow).

Any two of these will give you the third (via X = Y + Z). In this case, we used Y & Z because I think that they are the simplest to reason about (and therefore the most likely to be wanted). An argument could easily be made for others though, if someone feels strongly.

There are certainly some historical stats (# of unshares, etc.) and lots of per-page/frame stats that would be of interest as well. But, bit by bit...

Quoted 7 lines · Andres Lagar-Cavilla

diff -r 6e8b8fb2c8b2 -r 3fc7875c8d98 tools/libxl/libxl.h

tools/libxl/libxl.h +0 -0

@@ -350,6 +350,9 @@ int libxl_domain_rename(libxl_ctx *ctx,
  int libxl_domain_pause(libxl_ctx *ctx, uint32_t domid);
  int libxl_domain_unpause(libxl_ctx *ctx, uint32_t domid);
 

tools/libxl/libxl.h int libxl_domain_rename(libxl_ctx *ctx, · line 354

Quoted 2 lines

tools/libxl/libxl.h +2 -0

+long libxl_sharing_used_frames(libxl_ctx *ctx);
+long libxl_sharing_freed_pages(libxl_ctx *ctx);

I'm undecided but perhaps it would be appropriate to add these to libxl_physinfo? In which case the output of "xl physinfo" or "xl info" would be a nice home for these. Or perhaps a new meminfo or hostinfo struct?

tools/libxc/xc_memshr.c | 23 +++++++++++++++++++++++

 tools/libxc/xenctrl.h   |   6 ++++++
 2 files changed, 29 insertions(+), 0 deletions(-)

Signed-off-by Andres Lagar-Cavilla <[email protected]>

diff -r 3fc7875c8d98 -r 33935769e257 tools/libxc/xc_memshr.c

tools/libxc/xc_memshr.c +11 -0

+    domctl.domain               = (domid_t) source_domain;
+    op = &(domctl.u.mem_sharing_op);
+    op->op = XEN_DOMCTL_MEM_EVENT_OP_SHARING_ADD_PHYSMAP;
+    op->u.share.source_gfn      = source_gfn;
+    op->u.share.source_handle   = source_handle;
+    op->u.share.client_gfn      = client_gfn;
+    op->u.share.client_domain   = (uint64_t) client_domain;
+
+    return do_domctl(xch, &domctl);
+}
+
 int xc_memshr_share(xc_interface *xch,
                     uint32_t source_domain,
                     uint64_t source_gfn,

diff -r 3fc7875c8d98 -r 33935769e257 tools/libxc/xenctrl.h

tools/libxc/xenctrl.h +6 -0

@@ -1895,6 +1895,12 @@ int xc_memshr_nominate_gref(xc_interface
                             uint32_t domid,
                             grant_ref_t gref,
                             uint64_t *handle);
+int xc_memshr_add_to_physmap(xc_interface *xch,
+                    uint32_t source_domain,
+                    uint64_t source_gfn,
+                    uint64_t source_handle,
+                    uint32_t client_domain,
+                    uint64_t client_gfn);
 int xc_memshr_share(xc_interface *xch,
                     uint32_t source_domain,
                     uint64_t source_gfn,

tools/libxc/xc_memshr.c | 23 +++++++++++++++++++++++

 tools/libxc/xenctrl.h   |   6 ++++++
 2 files changed, 29 insertions(+), 0 deletions(-)

Signed-off-by Andres Lagar-Cavilla <[email protected]>

diff -r 3fc7875c8d98 -r 33935769e257 tools/libxc/xc_memshr.c

tools/libxc/xc_memshr.c +3 -0

@@ -86,6 +86,29 @@ int xc_memshr_nominate_gref(xc_interface
     return ret;
 }
 
+int xc_memshr_add_to_physmap(xc_interface *xch,
+                    uint32_t source_domain,
+                    uint64_t source_gfn,

tools/libxc/xc_memshr.c +4 -0

+
+    return do_domctl(xch, &domctl);
+}
+
 int xc_memshr_share(xc_interface *xch,
                     uint32_t source_domain,
                     uint64_t source_gfn,

diff -r 3fc7875c8d98 -r 33935769e257 tools/libxc/xenctrl.h

tools/libxc/xenctrl.h +6 -0

@@ -1895,6 +1895,12 @@ int xc_memshr_nominate_gref(xc_interface
                             uint32_t domid,
                             grant_ref_t gref,
                             uint64_t *handle);
+int xc_memshr_add_to_physmap(xc_interface *xch,
+                    uint32_t source_domain,
+                    uint64_t source_gfn,
+                    uint64_t source_handle,
+                    uint32_t client_domain,
+                    uint64_t client_gfn);
 int xc_memshr_share(xc_interface *xch,
                     uint32_t source_domain,
                     uint64_t source_gfn,

tools/libxc/xc_memshr.c | 14 ++++++++++++++

 tools/libxc/xenctrl.h   |   2 ++
 2 files changed, 16 insertions(+), 0 deletions(-)

Signed-off-by Adin Scannell <[email protected]>

diff -r 33935769e257 -r 6514004012c7 tools/libxc/xc_memshr.c

tools/libxc/xc_memshr.c +14 -0

@@ -211,3 +211,17 @@ int xc_memshr_debug_gref(xc_interface *x
     return do_domctl(xch, &domctl);
 }
 
+int xc_memshr_audit(xc_interface *xch,
+                    uint32_t domid)
+{
+    DECLARE_DOMCTL;
+    struct xen_domctl_mem_sharing_op *op;
+
+    domctl.cmd = XEN_DOMCTL_mem_sharing_op;
+    domctl.interface_version = XEN_DOMCTL_INTERFACE_VERSION;
+    domctl.domain = (domid_t)domid;
+    op = &(domctl.u.mem_sharing_op);
+    op->op = XEN_DOMCTL_MEM_EVENT_OP_SHARING_AUDIT;
+
+    return do_domctl(xch, &domctl);
+}

diff -r 33935769e257 -r 6514004012c7 tools/libxc/xenctrl.h

tools/libxc/xenctrl.h +2 -0

@@ -1921,6 +1921,8 @@ int xc_memshr_debug_mfn(xc_interface *xc
 int xc_memshr_debug_gref(xc_interface *xch,
                          uint32_t domid,
                          grant_ref_t gref);
+int xc_memshr_audit(xc_interface *xch,
+                    uint32_t domid);
 
 int xc_flask_load(xc_interface *xc_handle, char *buf, uint32_t size);
 int xc_flask_context_to_sid(xc_interface *xc_handle, char *buf, uint32_t size, uint32_t *sid);