[PATCH 4/6] libxc, libxl, hvmloader: strip out outdated VM generation ID implementation

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

The VM generation ID support in libxc/libxl was based on a draft
specification which subsequently changed considerably.  Remove much of
the code in anticipation of introducing something simpler that
conforms to the current specification from Microsoft.

Switch to using a HVM param (HVM_PARAM_VM_GENERATION_ID_ADDR) instead
of the hvmloader/generation-id-address XenStore key.  This simplifies
save/restore since it only needs to transfer the value of this param.

There are no changes to the migration stream format or the public
libxl API.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
 tools/firmware/hvmloader/acpi/build.c |    9 +++----
 tools/libxc/xc_domain_restore.c       |   44 +++------------------------------
 tools/libxc/xc_domain_save.c          |    5 ++--
 tools/libxc/xenguest.h                |    8 ++----
 tools/libxl/libxl_create.c            |   12 +++------
 tools/libxl/libxl_dom.c               |   25 ++-----------------
 tools/libxl/libxl_internal.h          |    8 ++----
 tools/libxl/libxl_save_callout.c      |   10 +++-----
 tools/libxl/libxl_save_helper.c       |    9 +++----
 tools/libxl/libxl_save_msgs_gen.pl    |    3 +--
 10 files changed, 26 insertions(+), 107 deletions(-)

diff --git a/tools/firmware/hvmloader/acpi/build.c b/tools/firmware/hvmloader/acpi/build.c
index 5c42d89..1431296 100644
--- a/tools/firmware/hvmloader/acpi/build.c
+++ b/tools/firmware/hvmloader/acpi/build.c
@@ -24,6 +24,7 @@
 #include "../config.h"
 #include "../util.h"
 #include <xen/hvm/hvm_xs_strings.h>
+#include <xen/hvm/params.h>
 
 #define ACPI_MAX_SECONDARY_TABLES 16
 
@@ -362,7 +363,6 @@ static int construct_secondary_tables(unsigned long *table_ptrs,
 static int new_vm_gid(struct acpi_info *acpi_info)
 {
     uint64_t vm_gid[2], *buf;
-    char addr[12];
     const char * s;
     char *end;
 
@@ -383,12 +383,9 @@ static int new_vm_gid(struct acpi_info *acpi_info)
         return 0;
     memcpy(buf, vm_gid, sizeof(vm_gid));
 
-    /* set into ACPI table and XenStore the address */
+    /* set into ACPI table and HVM param the address */
     acpi_info->vm_gid_addr = virt_to_phys(buf);
-    if ( snprintf(addr, sizeof(addr), "0x%lx", virt_to_phys(buf))
-         >= sizeof(addr) )
-        return 0;
-    xenstore_write("hvmloader/generation-id-address", addr);
+    hvm_param_set(HVM_PARAM_VM_GENERATION_ID_ADDR, acpi_info->vm_gid_addr);
 
     return 1;
 }
diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index bcb0ae0..cf1c489 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -1408,8 +1408,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       domid_t store_domid, unsigned int console_evtchn,
                       unsigned long *console_mfn, domid_t console_domid,
                       unsigned int hvm, unsigned int pae, int superpages,
-                      int no_incr_generationid, int checkpointed_stream,
-                      unsigned long *vm_generationid_addr,
+                      int checkpointed_stream,
                       struct restore_callbacks *callbacks)
 {
     DECLARE_DOMCTL;
@@ -1634,44 +1633,9 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                 xc_set_hvm_param(xch, dom, HVM_PARAM_VM86_TSS, pagebuf.vm86_tss);
             if ( pagebuf.console_pfn )
                 console_pfn = pagebuf.console_pfn;
-            if ( pagebuf.vm_generationid_addr ) {
-                if ( !no_incr_generationid ) {
-                    unsigned int offset;
-                    unsigned char *buf;
-                    unsigned long long generationid;
-
-                    /*
-                     * Map the VM generation id buffer and inject the new value.
-                     */
-
-                    pfn = pagebuf.vm_generationid_addr >> PAGE_SHIFT;
-                    offset = pagebuf.vm_generationid_addr & (PAGE_SIZE - 1);
-                
-                    if ( (pfn >= dinfo->p2m_size) ||
-                         (pfn_type[pfn] != XEN_DOMCTL_PFINFO_NOTAB) )
-                    {
-                        ERROR("generation id buffer frame is bad");
-                        goto out;
-                    }
-
-                    mfn = ctx->p2m[pfn];
-                    buf = xc_map_foreign_range(xch, dom, PAGE_SIZE,
-                                               PROT_READ | PROT_WRITE, mfn);
-                    if ( buf == NULL )
-                    {
-                        ERROR("xc_map_foreign_range for generation id"
-                              " buffer failed");
-                        goto out;
-                    }
-
-                    generationid = *(unsigned long long *)(buf + offset);
-                    *(unsigned long long *)(buf + offset) = generationid + 1;
-
-                    munmap(buf, PAGE_SIZE);
-                }
-
-                *vm_generationid_addr = pagebuf.vm_generationid_addr;
-            }
+            if ( pagebuf.vm_generationid_addr )
+                xc_set_hvm_param(xch, dom, HVM_PARAM_VM_GENERATION_ID_ADDR,
+                                 pagebuf.vm_generationid_addr);
 
             break;  /* our work here is done */
         }
diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index 71f9b59..42094e8 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -802,8 +802,7 @@ static int save_tsc_info(xc_interface *xch, uint32_t dom, int io_fd)
 
 int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iters,
                    uint32_t max_factor, uint32_t flags,
-                   struct save_callbacks* callbacks, int hvm,
-                   unsigned long vm_generationid_addr)
+                   struct save_callbacks* callbacks, int hvm)
 {
     xc_dominfo_t info;
     DECLARE_DOMCTL;
@@ -1634,7 +1633,7 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
         } chunk = { 0, };
 
         chunk.id = XC_SAVE_ID_HVM_GENERATION_ID_ADDR;
-        chunk.data = vm_generationid_addr;
+        xc_get_hvm_param(xch, dom, HVM_PARAM_VM_GENERATION_ID_ADDR, &chunk.data);
 
         if ( (chunk.data != 0) &&
              wrexact(io_fd, &chunk, sizeof(chunk)) )
diff --git a/tools/libxc/xenguest.h b/tools/libxc/xenguest.h
index 1f216cd..40bbac8 100644
--- a/tools/libxc/xenguest.h
+++ b/tools/libxc/xenguest.h
@@ -86,8 +86,7 @@ struct save_callbacks {
  */
 int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iters,
                    uint32_t max_factor, uint32_t flags /* XCFLAGS_xxx */,
-                   struct save_callbacks* callbacks, int hvm,
-                   unsigned long vm_generationid_addr);
+                   struct save_callbacks* callbacks, int hvm);
 
 
 /* callbacks provided by xc_domain_restore */
@@ -113,9 +112,7 @@ struct restore_callbacks {
  * @parm hvm non-zero if this is a HVM restore
  * @parm pae non-zero if this HVM domain has PAE support enabled
  * @parm superpages non-zero to allocate guest memory with superpages
- * @parm no_incr_generationid non-zero if generation id is NOT to be incremented
  * @parm checkpointed_stream non-zero if the far end of the stream is using checkpointing
- * @parm vm_generationid_addr returned with the address of the generation id buffer
  * @parm callbacks non-NULL to receive a callback to restore toolstack
  *       specific data
  * @return 0 on success, -1 on failure
@@ -125,8 +122,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       domid_t store_domid, unsigned int console_evtchn,
                       unsigned long *console_mfn, domid_t console_domid,
                       unsigned int hvm, unsigned int pae, int superpages,
-                      int no_incr_generationid, int checkpointed_stream,
-                      unsigned long *vm_generationid_addr,
+                      int checkpointed_stream,
                       struct restore_callbacks *callbacks);
 /**
  * xc_domain_restore writes a file to disk that contains the device
diff --git a/tools/libxl/libxl_create.c b/tools/libxl/libxl_create.c
index d015cf4..cae6f53 100644
--- a/tools/libxl/libxl_create.c
+++ b/tools/libxl/libxl_create.c
@@ -584,12 +584,7 @@ retry_transaction:
                         ARRAY_SIZE(rwperm));
     }
 
-    if (info->type == LIBXL_DOMAIN_TYPE_HVM)
-        libxl__xs_mkdir(gc, t,
-            libxl__sprintf(gc, "%s/hvmloader/generation-id-address", dom_path),
-                        rwperm, ARRAY_SIZE(rwperm));
-
-                    vm_list = libxl_list_vm(ctx, &nb_vm);
+    vm_list = libxl_list_vm(ctx, &nb_vm);
     if (!vm_list) {
         LOG(ERROR, "cannot get number of running guests");
         rc = ERROR_FAIL;
@@ -903,7 +898,7 @@ static void domcreate_bootloader_done(libxl__egc *egc,
         goto out;
     }
     libxl__xc_domain_restore(egc, dcs,
-                             hvm, pae, superpages, 1);
+                             hvm, pae, superpages);
     return;
 
  out:
@@ -911,7 +906,7 @@ static void domcreate_bootloader_done(libxl__egc *egc,
 }
 
 void libxl__srm_callout_callback_restore_results(unsigned long store_mfn,
-          unsigned long console_mfn, unsigned long genidad, void *user)
+          unsigned long console_mfn, void *user)
 {
     libxl__save_helper_state *shs = user;
     libxl__domain_create_state *dcs = CONTAINER_OF(shs, *dcs, shs);
@@ -920,7 +915,6 @@ void libxl__srm_callout_callback_restore_results(unsigned long store_mfn,
 
     state->store_mfn =            store_mfn;
     state->console_mfn =          console_mfn;
-    state->vm_generationid_addr = genidad;
     shs->need_results =           0;
 }
 
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 661999c..4804fdf 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -279,7 +279,6 @@ int libxl__build_pre(libxl__gc *gc, uint32_t domid,
 
     state->store_port = xc_evtchn_alloc_unbound(ctx->xch, domid, state->store_domid);
     state->console_port = xc_evtchn_alloc_unbound(ctx->xch, domid, state->console_domid);
-    state->vm_generationid_addr = 0;
 
     if (info->type == LIBXL_DOMAIN_TYPE_HVM)
         hvm_set_conf_params(ctx->xch, domid, info);
@@ -297,7 +296,7 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid,
     libxl_ctx *ctx = libxl__gc_owner(gc);
     char *dom_path, *vm_path;
     xs_transaction_t t;
-    char **ents, **hvm_ents;
+    char **ents;
     int i, rc;
 
     rc = libxl_domain_sched_params_set(CTX, domid, &info->sched_params);
@@ -334,13 +333,6 @@ int libxl__build_post(libxl__gc *gc, uint32_t domid,
                             ? "online" : "offline";
     }
 
-    hvm_ents = NULL;
-    if (info->type == LIBXL_DOMAIN_TYPE_HVM) {
-        hvm_ents = libxl__calloc(gc, 3, sizeof(char *));
-        hvm_ents[0] = "hvmloader/generation-id-address";
-        hvm_ents[1] = GCSPRINTF("0x%lx", state->vm_generationid_addr);
-    }
-
     dom_path = libxl__xs_get_dompath(gc, domid);
     if (!dom_path) {
         return ERROR_FAIL;
@@ -351,9 +343,6 @@ retry_transaction:
     t = xs_transaction_start(ctx->xsh);
 
     libxl__xs_writev(gc, t, dom_path, ents);
-    if (info->type == LIBXL_DOMAIN_TYPE_HVM)
-        libxl__xs_writev(gc, t, dom_path, hvm_ents);
-
     libxl__xs_writev(gc, t, dom_path, local_ents);
     libxl__xs_writev(gc, t, vm_path, vms_ents);
 
@@ -1502,7 +1491,6 @@ void libxl__domain_suspend(libxl__egc *egc, libxl__domain_suspend_state *dss)
     STATE_AO_GC(dss->ao);
     int port;
     int rc = ERROR_FAIL;
-    unsigned long vm_generationid_addr;
 
     /* Convenience aliases */
     const uint32_t domid = dss->domid;
@@ -1521,19 +1509,10 @@ void libxl__domain_suspend(libxl__egc *egc, libxl__domain_suspend_state *dss)
 
     switch (type) {
     case LIBXL_DOMAIN_TYPE_HVM: {
-        char *path;
-        char *addr;
-
-        path = GCSPRINTF("%s/hvmloader/generation-id-address",
-                              libxl__xs_get_dompath(gc, domid));
-        addr = libxl__xs_read(gc, XBT_NULL, path);
-
-        vm_generationid_addr = (addr) ? strtoul(addr, NULL, 0) : 0;
         dss->hvm = 1;
         break;
     }
     case LIBXL_DOMAIN_TYPE_PV:
-        vm_generationid_addr = 0;
         dss->hvm = 0;
         break;
     default:
@@ -1580,7 +1559,7 @@ void libxl__domain_suspend(libxl__egc *egc, libxl__domain_suspend_state *dss)
     callbacks->switch_qemu_logdirty = libxl__domain_suspend_common_switch_qemu_logdirty;
     dss->shs.callbacks.save.toolstack_save = libxl__toolstack_save;
 
-    libxl__xc_domain_save(egc, dss, vm_generationid_addr);
+    libxl__xc_domain_save(egc, dss);
     return;
 
  out:
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index 082749e..457424f 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -960,8 +960,6 @@ typedef struct {
     uint32_t console_domid;
     unsigned long console_mfn;
 
-    unsigned long vm_generationid_addr;
-
     char *saved_state;
 
     libxl__file_reference pv_kernel;
@@ -2757,8 +2755,7 @@ _hidden void libxl__domain_suspend(libxl__egc *egc,
 
 
 /* calls libxl__xc_domain_suspend_done when done */
-_hidden void libxl__xc_domain_save(libxl__egc*, libxl__domain_suspend_state*,
-                                   unsigned long vm_generationid_addr);
+_hidden void libxl__xc_domain_save(libxl__egc*, libxl__domain_suspend_state*);
 /* If rc==0 then retval is the return value from xc_domain_save
  * and errnoval is the errno value it provided.
  * If rc!=0, retval and errnoval are undefined. */
@@ -2782,8 +2779,7 @@ _hidden int libxl__toolstack_save(uint32_t domid, uint8_t **buf,
 /* calls libxl__xc_domain_restore_done when done */
 _hidden void libxl__xc_domain_restore(libxl__egc *egc,
                                       libxl__domain_create_state *dcs,
-                                      int hvm, int pae, int superpages,
-                                      int no_incr_generationid);
+                                      int hvm, int pae, int superpages);
 /* If rc==0 then retval is the return value from xc_domain_save
  * and errnoval is the errno value it provided.
  * If rc!=0, retval and errnoval are undefined. */
diff --git a/tools/libxl/libxl_save_callout.c b/tools/libxl/libxl_save_callout.c
index c35da4d..1c9f806 100644
--- a/tools/libxl/libxl_save_callout.c
+++ b/tools/libxl/libxl_save_callout.c
@@ -41,8 +41,7 @@ static void helper_done(libxl__egc *egc, libxl__save_helper_state *shs);
 /*----- entrypoints -----*/
 
 void libxl__xc_domain_restore(libxl__egc *egc, libxl__domain_create_state *dcs,
-                              int hvm, int pae, int superpages,
-                              int no_incr_generationid)
+                              int hvm, int pae, int superpages)
 {
     STATE_AO_GC(dcs->ao);
 
@@ -59,7 +58,7 @@ void libxl__xc_domain_restore(libxl__egc *egc, libxl__domain_create_state *dcs,
         state->store_port,
         state->store_domid, state->console_port,
         state->console_domid,
-        hvm, pae, superpages, no_incr_generationid,
+        hvm, pae, superpages,
         cbflags, dcs->checkpointed_stream,
     };
 
@@ -75,8 +74,7 @@ void libxl__xc_domain_restore(libxl__egc *egc, libxl__domain_create_state *dcs,
                argnums, ARRAY_SIZE(argnums));
 }
 
-void libxl__xc_domain_save(libxl__egc *egc, libxl__domain_suspend_state *dss,
-                           unsigned long vm_generationid_addr)
+void libxl__xc_domain_save(libxl__egc *egc, libxl__domain_suspend_state *dss)
 {
     STATE_AO_GC(dss->ao);
     int r, rc, toolstack_data_fd = -1;
@@ -112,7 +110,7 @@ void libxl__xc_domain_save(libxl__egc *egc, libxl__domain_suspend_state *dss,
     }
 
     const unsigned long argnums[] = {
-        dss->domid, 0, 0, dss->xcflags, dss->hvm, vm_generationid_addr,
+        dss->domid, 0, 0, dss->xcflags, dss->hvm,
         toolstack_data_fd, toolstack_data_len,
         cbflags,
     };
diff --git a/tools/libxl/libxl_save_helper.c b/tools/libxl/libxl_save_helper.c
index b259bd0..c760dd3 100644
--- a/tools/libxl/libxl_save_helper.c
+++ b/tools/libxl/libxl_save_helper.c
@@ -211,7 +211,6 @@ int main(int argc, char **argv)
         uint32_t max_factor =      strtoul(NEXTARG,0,10);
         uint32_t flags =           strtoul(NEXTARG,0,10);
         int hvm =                  atoi(NEXTARG);
-        unsigned long genidad =    strtoul(NEXTARG,0,10);
         toolstack_save_fd  =       atoi(NEXTARG);
         toolstack_save_len =       strtoul(NEXTARG,0,10);
         unsigned cbflags =         strtoul(NEXTARG,0,10);
@@ -224,7 +223,7 @@ int main(int argc, char **argv)
 
         startup("save");
         r = xc_domain_save(xch, io_fd, dom, max_iters, max_factor, flags,
-                           &helper_save_callbacks, hvm, genidad);
+                           &helper_save_callbacks, hvm);
         complete(r);
 
     } else if (!strcmp(mode,"--restore-domain")) {
@@ -238,7 +237,6 @@ int main(int argc, char **argv)
         unsigned int hvm =         strtoul(NEXTARG,0,10);
         unsigned int pae =         strtoul(NEXTARG,0,10);
         int superpages =           strtoul(NEXTARG,0,10);
-        int no_incr_genidad =      strtoul(NEXTARG,0,10);
         unsigned cbflags =         strtoul(NEXTARG,0,10);
         int checkpointed =         strtoul(NEXTARG,0,10);
         assert(!*++argv);
@@ -247,15 +245,14 @@ int main(int argc, char **argv)
 
         unsigned long store_mfn = 0;
         unsigned long console_mfn = 0;
-        unsigned long genidad = 0;
 
         startup("restore");
         r = xc_domain_restore(xch, io_fd, dom, store_evtchn, &store_mfn,
                               store_domid, console_evtchn, &console_mfn,
                               console_domid, hvm, pae, superpages,
-                              no_incr_genidad, checkpointed, &genidad,
+                              checkpointed,
                               &helper_restore_callbacks);
-        helper_stub_restore_results(store_mfn,console_mfn,genidad,0);
+        helper_stub_restore_results(store_mfn,console_mfn,0);
         complete(r);
 
     } else {
diff --git a/tools/libxl/libxl_save_msgs_gen.pl b/tools/libxl/libxl_save_msgs_gen.pl
index 745e2ac..88f4921 100755
--- a/tools/libxl/libxl_save_msgs_gen.pl
+++ b/tools/libxl/libxl_save_msgs_gen.pl
@@ -32,8 +32,7 @@ our @msgs = (
     [  7, 'rcxW',   "toolstack_restore",     [qw(uint32_t domid
                                                 BLOCK tsdata)] ],
     [  8, 'r',      "restore_results",       ['unsigned long', 'store_mfn',
-                                              'unsigned long', 'console_mfn',
-                                              'unsigned long', 'genidad'] ],
+                                              'unsigned long', 'console_mfn'] ],
     [  9, 'srW',    "complete",              [qw(int retval
                                                  int errnoval)] ],
 );
-- 
1.7.10.4