libxc: introduce XC_SAVE_ID_TOOLSTACK

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

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>

6 files changed, 94 insertions, 4 deletions

diff --git a/tools/libxc/xc_domain_restore.c b/tools/libxc/xc_domain_restore.c
index 3e4d5183a5..6227d43ffd 100644
--- a/tools/libxc/xc_domain_restore.c
+++ b/tools/libxc/xc_domain_restore.c
@@ -659,6 +659,11 @@ static void tailbuf_free(tailbuf_t *buf)
         tailbuf_free_pv(&buf->u.pv);
 }
 
+struct toolstack_data_t {
+    uint8_t *data;
+    uint32_t len;
+};
+
 typedef struct {
     void* pages;
     /* pages is of length nr_physpages, pfn_types is of length nr_pages */
@@ -685,6 +690,8 @@ typedef struct {
     uint64_t acpi_ioport_location;
     uint64_t viridian;
     uint64_t vm_generationid_addr;
+
+    struct toolstack_data_t tdata;
 } pagebuf_t;
 
 static int pagebuf_init(pagebuf_t* buf)
@@ -695,6 +702,10 @@ static int pagebuf_init(pagebuf_t* buf)
 
 static void pagebuf_free(pagebuf_t* buf)
 {
+    if (buf->tdata.data != NULL) {
+        free(buf->tdata.data);
+        buf->tdata.data = NULL;
+    }
     if (buf->pages) {
         free(buf->pages);
         buf->pages = NULL;
@@ -863,6 +874,19 @@ 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, &buf->tdata.len, sizeof(buf->tdata.len));
+            buf->tdata.data = (uint8_t*) realloc(buf->tdata.data, buf->tdata.len);
+            if ( buf->tdata.data == NULL )
+            {
+                PERROR("error memory allocation");
+                return -1;
+            }
+            RDEXACT(fd, buf->tdata.data, buf->tdata.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
@@ -1299,7 +1323,8 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       unsigned long *console_mfn, domid_t console_domid,
                       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;
@@ -1347,6 +1372,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
 
     pagebuf_t pagebuf;
     tailbuf_t tailbuf, tmptail;
+    struct toolstack_data_t tdata, tdatatmp;
     void* vcpup;
     uint64_t console_pfn = 0;
 
@@ -1359,6 +1385,7 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     pagebuf_init(&pagebuf);
     memset(&tailbuf, 0, sizeof(tailbuf));
     tailbuf.ishvm = hvm;
+    memset(&tdata, 0, sizeof(tdata));
 
     memset(ctx, 0, sizeof(*ctx));
 
@@ -1624,6 +1651,10 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
         ERROR("Error, unknow acpi ioport location (%i)", pagebuf.acpi_ioport_location);
     }
 
+    tdatatmp = tdata;
+    tdata = pagebuf.tdata;
+    pagebuf.tdata = tdatatmp;
+
     if ( ctx->last_checkpoint )
     {
         // DPRINTF("Last checkpoint, finishing\n");
@@ -2074,6 +2105,26 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
     goto out;
 
   finish_hvm:
+    if ( tdata.data != NULL )
+    {
+        if ( callbacks != NULL && callbacks->toolstack_restore != NULL )
+        {
+            rc = callbacks->toolstack_restore(dom, tdata.data, tdata.len,
+                        callbacks->data);
+            free(tdata.data);
+            if ( rc < 0 )
+            {
+                PERROR("error calling toolstack_restore");
+                goto out;
+            }
+        } else {
+            rc = -1;
+            ERROR("toolstack data available but no callback provided\n");
+            free(tdata.data);
+            goto out;
+        }
+    }
+
     /* 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 a9216ddf71..fcc7718ecb 100644
--- a/tools/libxc/xc_domain_save.c
+++ b/tools/libxc/xc_domain_save.c
@@ -1723,6 +1723,23 @@ 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 8d885d3133..6435f659af 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,
@@ -83,7 +103,8 @@ int xc_domain_restore(xc_interface *xch, int io_fd, uint32_t dom,
                       unsigned long *console_mfn, domid_t console_domid,
                       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 89f3504911..04e7892698 100644
--- a/tools/libxc/xg_save_restore.h
+++ b/tools/libxc/xg_save_restore.h
@@ -258,6 +258,7 @@
 #define XC_SAVE_ID_HVM_PAGING_RING_PFN  -15
 #define XC_SAVE_ID_HVM_ACCESS_RING_PFN  -16
 #define XC_SAVE_ID_HVM_SHARING_RING_PFN -17
+#define XC_SAVE_ID_TOOLSTACK          -18 /* 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 c246211823..ba8fea4982 100644
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -474,7 +474,7 @@ int libxl__domain_restore_common(libxl__gc *gc, uint32_t domid,
                            state->store_domid, state->console_port,
                            &state->console_mfn, state->console_domid,
                            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 e41a133732..0235579622 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, 0,
                             console_evtchn, &console_mfn, 0, hvm, pae, superpages,
-                            0, NULL);
+                            0, NULL, NULL);
 
     if ( ret == 0 )
     {