[PATCH v18 1/2] tools/libxc: add VM forking functions

[Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>]

Add functions to issue VM forking hypercalls

Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx>
---
 tools/libxc/include/xenctrl.h | 14 ++++++++++++++
 tools/libxc/xc_memshr.c       | 26 ++++++++++++++++++++++++++
 2 files changed, 40 insertions(+)

diff --git a/tools/libxc/include/xenctrl.h b/tools/libxc/include/xenctrl.h
index 5f25c5a6d4..0a6ff93229 100644
--- a/tools/libxc/include/xenctrl.h
+++ b/tools/libxc/include/xenctrl.h
@@ -2232,6 +2232,20 @@ int xc_memshr_range_share(xc_interface *xch,
                           uint64_t first_gfn,
                           uint64_t last_gfn);
 
+int xc_memshr_fork(xc_interface *xch,
+                   uint32_t source_domain,
+                   uint32_t client_domain,
+                   bool allow_with_iommu);
+
+/*
+ * Note: this function is only intended to be used on short-lived forks that
+ * haven't yet aquired a lot of memory. In case the fork has a lot of memory
+ * it is likely more performant to create a new fork with xc_memshr_fork.
+ *
+ * With VMs that have a lot of memory this call may block for a long time.
+ */
+int xc_memshr_fork_reset(xc_interface *xch, uint32_t forked_domain);
+
 /* Debug calls: return the number of pages referencing the shared frame backing
  * the input argument. Should be one or greater.
  *
diff --git a/tools/libxc/xc_memshr.c b/tools/libxc/xc_memshr.c
index 97e2e6a8d9..2300cc7075 100644
--- a/tools/libxc/xc_memshr.c
+++ b/tools/libxc/xc_memshr.c
@@ -239,6 +239,32 @@ int xc_memshr_debug_gref(xc_interface *xch,
     return xc_memshr_memop(xch, domid, &mso);
 }
 
+int xc_memshr_fork(xc_interface *xch, uint32_t pdomid, uint32_t domid,
+                   bool allow_with_iommu)
+{
+    xen_mem_sharing_op_t mso;
+
+    memset(&mso, 0, sizeof(mso));
+
+    mso.op = XENMEM_sharing_op_fork;
+    mso.u.fork.parent_domain = pdomid;
+
+    if ( allow_with_iommu )
+        mso.u.fork.flags |= XENMEM_FORK_WITH_IOMMU_ALLOWED;
+
+    return xc_memshr_memop(xch, domid, &mso);
+}
+
+int xc_memshr_fork_reset(xc_interface *xch, uint32_t domid)
+{
+    xen_mem_sharing_op_t mso;
+
+    memset(&mso, 0, sizeof(mso));
+    mso.op = XENMEM_sharing_op_fork_reset;
+
+    return xc_memshr_memop(xch, domid, &mso);
+}
+
 int xc_memshr_audit(xc_interface *xch)
 {
     xen_mem_sharing_op_t mso;
-- 
2.25.1