[PATCH v3 1/2] libxc: introduce XC_SAVE_ID_TOOLSTACK

[Stefano Stabellini <stefano.stabellini@eu.citrix.com>]

Introduce a new save_id to save/restore toolstack specific extra
information.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---
 tools/libxc/xc_domain_restore.c |   32 +++++++++++++++++++++++++++++++-
 tools/libxc/xc_domain_save.c    |   17 +++++++++++++++++
 tools/libxc/xenguest.h          |   23 ++++++++++++++++++++++-
 tools/libxc/xg_save_restore.h   |    1 +
 tools/libxl/libxl_dom.c         |    2 +-
 tools/xcutils/xc_restore.c      |    2 +-
 6 files changed, 73 insertions(+), 4 deletions(-)

diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index 3fda6f8..ead3df4 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -45,6 +45,8 @@ struct restore_ctx {
     int last_checkpoint; /* Set when we should commit to the current checkpoint when it completes. */
     int compressing; /* Set when sender signals that pages would be sent compressed (for Remus) */
     struct domain_info_context dinfo;
+    uint8_t *toolstack_data;
+    uint32_t toolstack_data_len;
 };
 
 #define HEARTBEAT_MS 1000
@@ -827,6 +829,20 @@ static int pagebuf_get_one(xc_interface *xch, struct restore_ctx *ctx,
         }
         return pagebuf_get_one(xch, ctx, buf, fd, dom);
 
+    case XC_SAVE_ID_TOOLSTACK:
+        {
+            RDEXACT(fd, &ctx->toolstack_data_len,
+                    sizeof(ctx->toolstack_data_len));
+            ctx->toolstack_data = (uint8_t*) malloc(ctx->toolstack_data_len);
+            if ( ctx->toolstack_data == NULL )
+            {
+                PERROR("error memory allocation");
+                return -1;
+            }
+            RDEXACT(fd, ctx->toolstack_data, ctx->toolstack_data_len);
+            return pagebuf_get_one(xch, ctx, buf, fd, dom);
+        }
+
     case XC_SAVE_ID_ENABLE_COMPRESSION:
         /* We cannot set compression flag directly in pagebuf structure,
          * since this pagebuf still has uncompressed pages that are yet to
@@ -1262,7 +1278,8 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       unsigned int console_evtchn, unsigned long *console_mfn,
                       unsigned int hvm, unsigned int pae, int superpages,
                       int no_incr_generationid,
-                      unsigned long *vm_generationid_addr)
+                      unsigned long *vm_generationid_addr,
+                      struct restore_callbacks *callbacks)
 {
     DECLARE_DOMCTL;
     int rc = 1, frc, i, j, n, m, pae_extended_cr3 = 0, ext_vcpucontext = 0;
@@ -2023,6 +2040,19 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     goto out;
 
   finish_hvm:
+    if ( callbacks != NULL && callbacks->toolstack_restore != NULL )
+    {
+        if ( callbacks->toolstack_restore(dom,
+                    ctx->toolstack_data, ctx->toolstack_data_len,
+                    callbacks->data) < 0 )
+        {
+            PERROR("error calling toolstack_restore");
+            free(ctx->toolstack_data);
+            goto out;
+        }
+    }
+    free(ctx->toolstack_data);
+
     /* Dump the QEMU state to a state file for QEMU to load */
     if ( dump_qemu(xch, dom, &tailbuf.u.hvm) ) {
         PERROR("Error dumping QEMU state to file");
diff --git a/tools/libxc/xc_domain_save.c b/tools/libxc/xc_domain_save.c
index f473dd7..318c433 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -1687,6 +1687,23 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
         }
     }
 
+    if ( callbacks != NULL && callbacks->toolstack_save != NULL )
+    {
+        int id = XC_SAVE_ID_TOOLSTACK;
+        uint8_t *buf;
+        uint32_t len;
+
+        if ( callbacks->toolstack_save(dom, &buf, &len, callbacks->data) < 0 )
+        {
+            PERROR("Error calling toolstack_save");
+            goto out;
+        }
+        wrexact(io_fd, &id, sizeof(id));
+        wrexact(io_fd, &len, sizeof(len));
+        wrexact(io_fd, buf, len);
+        free(buf);
+    }
+
     if ( !callbacks->checkpoint )
     {
         /*
diff --git a/tools/libxc/xenguest.h b/tools/libxc/xenguest.h
index 6026370..76aa475 100644
--- a/tools/libxc/xenguest.h
+++ b/tools/libxc/xenguest.h
@@ -44,6 +44,14 @@ struct save_callbacks {
     /* Enable qemu-dm logging dirty pages to xen */
     int (*switch_qemu_logdirty)(int domid, unsigned enable, void *data); /* HVM only */
 
+    /* Save toolstack specific data
+     * @param buf the buffer with the data to be saved
+     * @param len the length of the buffer
+     * The callee allocates the buffer, the caller frees it (buffer must
+     * be free'able).
+     */
+    int (*toolstack_save)(uint32_t domid, uint8_t **buf, uint32_t *len, void *data);
+
     /* to be provided as the last argument to each callback function */
     void* data;
 };
@@ -62,6 +70,16 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
                    unsigned long vm_generationid_addr);
 
 
+/* callbacks provided by xc_domain_restore */
+struct restore_callbacks {
+    /* callback to restore toolstack specific data */
+    int (*toolstack_restore)(uint32_t domid, uint8_t *buf,
+            uint32_t size, void* data);
+
+    /* to be provided as the last argument to each callback function */
+    void* data;
+};
+
 /**
  * This function will restore a saved domain.
  *
@@ -75,6 +93,8 @@ int xc_domain_save(xc_interface *xch, int io_fd, uint32_t dom, uint32_t max_iter
  * @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 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
  */
 int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
@@ -82,7 +102,8 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       unsigned int console_evtchn, unsigned long *console_mfn,
                       unsigned int hvm, unsigned int pae, int superpages,
                       int no_incr_generationid,
-		      unsigned long *vm_generationid_addr);
+                      unsigned long *vm_generationid_addr,
+                      struct restore_callbacks *callbacks);
 /**
  * xc_domain_restore writes a file to disk that contains the device
  * model saved state.
diff --git a/tools/libxc/xg_save_restore.h b/tools/libxc/xg_save_restore.h
index 6286b68..46fdeaa 100644
--- a/tools/libxc/xg_save_restore.h
+++ b/tools/libxc/xg_save_restore.h
@@ -254,6 +254,7 @@
 #define XC_SAVE_ID_COMPRESSED_DATA    -12 /* Marker to indicate arrival of compressed data */
 #define XC_SAVE_ID_ENABLE_COMPRESSION -13 /* Marker to enable compression logic at receiver side */
 #define XC_SAVE_ID_HVM_GENERATION_ID_ADDR -14
+#define XC_SAVE_ID_TOOLSTACK          -15 /* Optional toolstack specific info */
 
 /*
 ** We process save/restore/migrate in batches of pages; the below
diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index 91643a2..2c5eec5 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -379,7 +379,7 @@ int libxl__domain_restore_common(libxl__gc *gc, uint32_t domid,
                            state->store_port, &state->store_mfn,
                            state->console_port, &state->console_mfn,
                            hvm, pae, superpages, no_incr_generationid,
-                           &state->vm_generationid_addr);
+                           &state->vm_generationid_addr, NULL);
     if ( rc ) {
         LIBXL__LOG_ERRNO(ctx, LIBXL__LOG_ERROR, "restoring domain");
         return ERROR_FAIL;
diff --git a/tools/xcutils/xc_restore.c b/tools/xcutils/xc_restore.c
index 63d53a8..306a10e 100644
--- a/tools/xcutils/xc_restore.c
+++ b/tools/xcutils/xc_restore.c
@@ -47,7 +47,7 @@ main(int argc, char **argv)
 
     ret = xc_domain_restore(xch, io_fd, domid, store_evtchn, &store_mfn,
                             console_evtchn, &console_mfn, hvm, pae, superpages,
-                            0, NULL);
+                            0, NULL, NULL);
 
     if ( ret == 0 )
     {
-- 
1.7.2.5