shadow: track video RAM dirty bits

This adds a new HVM op that enables tracking dirty bits of a range of
video RAM.  The idea is to optimize just for the most common case
(only one guest mapping, with sometimes some temporary other
mappings), which permits to keep the overhead on shadow as low as
possible.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/tools/libxc/xc_misc.c b/tools/libxc/xc_misc.c
index c79e14a563..c68461a496 100644
--- a/tools/libxc/xc_misc.c
+++ b/tools/libxc/xc_misc.c
@@ -236,6 +236,37 @@ int xc_hvm_set_pci_link_route(
     return rc;
 }
 
+int xc_hvm_track_dirty_vram(
+    int xc_handle, domid_t dom,
+    uint64_t first_pfn, uint64_t nr,
+    unsigned long *dirty_bitmap)
+{
+    DECLARE_HYPERCALL;
+    struct xen_hvm_track_dirty_vram arg;
+    int rc;
+
+    hypercall.op     = __HYPERVISOR_hvm_op;
+    hypercall.arg[0] = HVMOP_track_dirty_vram;
+    hypercall.arg[1] = (unsigned long)&arg;
+
+    arg.domid     = dom;
+    arg.first_pfn = first_pfn;
+    arg.nr        = nr;
+    set_xen_guest_handle(arg.dirty_bitmap, (uint8_t *)dirty_bitmap);
+
+    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
+    {
+        PERROR("Could not lock memory");
+        return rc;
+    }
+
+    rc = do_xen_hypercall(xc_handle, &hypercall);
+
+    unlock_pages(&arg, sizeof(arg));
+
+    return rc;
+}
+
 void *xc_map_foreign_pages(int xc_handle, uint32_t dom, int prot,
                            const xen_pfn_t *arr, int num)
 {