[PATCH 5/6] libxl: allow a generation ID to be specified at domain creation

[David Vrabel <david.vrabel@citrix.com>]

Toolstacks may specify a VM generation ID using the
u.hvm.generation_id field into libxl_domain_build_info structure, when
creating a domain.

The toolstack is responsible for providing the correct generation ID
according to the Microsoft specification (e.g., generating new random
ones as appropriate when restoring).

Although the specification requires that a ACPI Notify event is raised
if the generation ID is changed, the generation ID is never changed
when the domain is in a state to receive such an event (it's either
newly created or suspended).

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 tools/libxl/Makefile         |    1 +
 tools/libxl/libxl.h          |    5 +++
 tools/libxl/libxl_dom.c      |   10 +++++
 tools/libxl/libxl_internal.h |    4 ++
 tools/libxl/libxl_types.idl  |    1 +
 tools/libxl/libxl_vm_genid.c |   89 ++++++++++++++++++++++++++++++++++++++++++
 6 files changed, 110 insertions(+)
 create mode 100644 tools/libxl/libxl_vm_genid.c

diff --git a/tools/libxl/Makefile b/tools/libxl/Makefile
index 4cfa275..5d0e2ec 100644
--- a/tools/libxl/Makefile
+++ b/tools/libxl/Makefile
@@ -77,6 +77,7 @@ LIBXL_OBJS = flexarray.o libxl.o libxl_create.o libxl_dm.o libxl_pci.o \
 			libxl_json.o libxl_aoutils.o libxl_numa.o \
 			libxl_save_callout.o _libxl_save_msgs_callout.o \
 			libxl_qmp.o libxl_event.o libxl_fork.o $(LIBXL_OBJS-y)
+LIBXL_OBJS += libxl_vm_genid.o
 LIBXL_OBJS += _libxl_types.o libxl_flask.o _libxl_types_internal.o
 
 LIBXL_TESTS += timedereg
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 80947c3..9dd57fd 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -95,6 +95,11 @@
 #define LIBXL_HAVE_BUILDINFO_EVENT_CHANNELS 1
 
 /*
+ * libxl_domain_build_info has the u.hvm.generation_id field.
+ */
+#define LIBXL_HAVE_BUILDINFO_HVM_GENERATION_ID 1
+
+/*
  * LIBXL_HAVE_DEVICE_DISK_DIRECT_IO_SAFE indicates that a
  * 'direct_io_safe' field (of boolean type) is present in
  * libxl_device_disk.
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 4804fdf..80bc9ff 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -314,6 +314,16 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid,
     if (info->cpuid != NULL)
         libxl_cpuid_set(ctx, domid, info->cpuid);
 
+    if (info->type == LIBXL_DOMAIN_TYPE_HVM 
+            && !libxl_uuid_is_nil(&info->u.hvm.generation_id)) {
+        rc = libxl__vm_generation_id_set(CTX, domid,
+                                         &info->u.hvm.generation_id);
+        if (rc) {
+            LOG(ERROR, "Failed to set VM Generation ID");
+            return rc;
+        }
+    }
+
     ents = libxl__calloc(gc, 12 + (info->max_vcpus * 2) + 2, sizeof(char *));
     ents[0] = "memory/static-max";
     ents[1] = GCSPRINTF("%"PRId64, info->max_memkb);
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 457424f..d938b90 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -3052,6 +3052,10 @@ void libxl__numa_candidate_put_nodemap(libxl__gc *gc,
     libxl_bitmap_copy(CTX, &cndt->nodemap, nodemap);
 }
 
+_hidden int libxl__vm_generation_id_set(libxl_ctx *ctx, uint32_t domid,
+                                        const libxl_uuid *uuid);
+
+
 /* Som handy macros for defbool type. */
 #define LIBXL__DEFBOOL_DEFAULT     (0)
 #define LIBXL__DEFBOOL_FALSE       (-1)
diff --git a/tools/libxl/libxl_types.idl b/tools/libxl/libxl_types.idl
index 52f1aa9..7800509 100644
--- a/tools/libxl/libxl_types.idl
+++ b/tools/libxl/libxl_types.idl
@@ -373,6 +373,7 @@ libxl_domain_build_info = Struct("domain_build_info",[
                                        ("xen_platform_pci", libxl_defbool),
                                        ("usbdevice_list",   libxl_string_list),
                                        ("vendor_device",    libxl_vendor_device),
+                                       ("generation_id",    libxl_uuid),
                                        ])),
                  ("pv", Struct(None, [("kernel", string),
                                       ("slack_memkb", MemKB),
diff --git a/tools/libxl/libxl_vm_genid.c b/tools/libxl/libxl_vm_genid.c
new file mode 100644
index 0000000..378dcf2
--- /dev/null
+++ b/tools/libxl/libxl_vm_genid.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2014 Citrix Systems R&D Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published
+ * by the Free Software Foundation; version 2.1 only. with the special
+ * exception on linking described in file LICENSE.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ */
+
+#include "libxl_osdeps.h" /* must come before any other headers */
+
+#include "libxl_internal.h"
+
+#include <xenctrl.h>
+#include <xen/hvm/params.h>
+
+/*
+ * Set a HVM domain's VM Generation ID.
+ *
+ * For further details, refer to the "Virtual Machine Generation ID"
+ * document from Microsoft.
+ * 
+ *   http://www.microsoft.com/en-us/download/details.aspx?id=30707
+ */
+int libxl__vm_generation_id_set(libxl_ctx *ctx, uint32_t domid,
+                                const libxl_uuid *uuid)
+{
+    GC_INIT(ctx);
+    char *dom_path;
+    char *key;
+    uint64_t genid[2];
+    uint64_t paddr = 0;
+    int rc;
+
+    memcpy(genid, libxl_uuid_bytearray((libxl_uuid *)uuid), 16);
+
+    /*
+     * Set the "platform/generation-id" XenStore key to pass the ID to
+     * hvmloader.
+     */
+    dom_path = libxl__xs_get_dompath(gc, domid);
+    if (!dom_path) {
+        rc = ERROR_FAIL;
+        goto out;
+    }
+    key = libxl__sprintf(gc, "%s/platform/generation-id", dom_path);
+    rc = libxl__xs_write(gc, XBT_NULL, key, "%"PRIu64 ":%" PRIu64,
+                         genid[0], genid[1]);
+    if (rc < 0)
+        goto out;
+
+    /*
+     * Update the ID in guest memory (if available).
+     */
+    xc_get_hvm_param(ctx->xch, domid, HVM_PARAM_VM_GENERATION_ID_ADDR, &paddr);
+    if (paddr) {
+        void *vaddr;
+
+        vaddr = xc_map_foreign_range(ctx->xch, domid, XC_PAGE_SIZE,
+                                     PROT_READ | PROT_WRITE,
+                                     paddr >> XC_PAGE_SHIFT);
+        if (vaddr == NULL) {
+            rc = ERROR_FAIL;
+            goto out;
+        }
+        memcpy(vaddr + (paddr & ~XC_PAGE_MASK), genid, 2 * sizeof(*genid));
+        munmap(vaddr, XC_PAGE_SIZE);
+
+        /*
+         * The spec requries an ACPI Notify event is injected into the
+         * guest when the generation ID is changed.
+         *
+         * This is only called for domains that are suspended or newly
+         * created and they won't be in a state to receive such an
+         * event.
+         */
+    }
+
+    rc = 0;
+
+  out:
+    GC_FREE;
+    return rc;
+}
-- 
1.7.10.4