[Xen-devel] [PATCH Remus v2 01/10] tools/libxc: adjust the memory allocation for migration

[Yang Hongyang <yanghy@xxxxxxxxxxxxxx>]

Move the memory allocation before the concrete live/nolive save
in order to avoid the free/alloc memory loop when using Remus.
Rename the to_send bitmap to dirty_bitmap.

Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
---
 tools/libxc/xc_sr_common.h |  1 +
 tools/libxc/xc_sr_save.c   | 68 ++++++++++++++++++++--------------------------
 2 files changed, 31 insertions(+), 38 deletions(-)

diff --git a/tools/libxc/xc_sr_common.h b/tools/libxc/xc_sr_common.h
index ef42412..95e3f5d 100644
--- a/tools/libxc/xc_sr_common.h
+++ b/tools/libxc/xc_sr_common.h
@@ -182,6 +182,7 @@ struct xc_sr_context
             unsigned nr_batch_pfns;
             unsigned long *deferred_pages;
             unsigned long nr_deferred_pages;
+            xc_hypercall_buffer_t dirty_bitmap_hbuf;
         } save;
 
         struct /* Restore data. */
diff --git a/tools/libxc/xc_sr_save.c b/tools/libxc/xc_sr_save.c
index 5d9c267..cc3e6b1 100644
--- a/tools/libxc/xc_sr_save.c
+++ b/tools/libxc/xc_sr_save.c
@@ -475,24 +475,12 @@ static int update_progress_string(struct xc_sr_context 
*ctx,
 static int send_domain_memory_live(struct xc_sr_context *ctx)
 {
     xc_interface *xch = ctx->xch;
-    DECLARE_HYPERCALL_BUFFER(unsigned long, to_send);
     xc_shadow_op_stats_t stats = { 0, ctx->save.p2m_size };
     char *progress_str = NULL;
     unsigned x;
     int rc = -1;
-
-    to_send = xc_hypercall_buffer_alloc_pages(
-        xch, to_send, NRPAGES(bitmap_size(ctx->save.p2m_size)));
-
-    ctx->save.batch_pfns = malloc(MAX_BATCH_SIZE *
-                                  sizeof(*ctx->save.batch_pfns));
-    ctx->save.deferred_pages = calloc(1, bitmap_size(ctx->save.p2m_size));
-
-    if ( !ctx->save.batch_pfns || !to_send || !ctx->save.deferred_pages )
-    {
-        ERROR("Unable to allocate memory for to_{send,fix}/batch bitmaps");
-        goto out;
-    }
+    DECLARE_HYPERCALL_BUFFER_SHADOW(unsigned long, dirty_bitmap,
+                                    (&ctx->save.dirty_bitmap_hbuf));
 
     rc = enable_logdirty(ctx);
     if ( rc )
@@ -512,7 +500,7 @@ static int send_domain_memory_live(struct xc_sr_context 
*ctx)
     {
         if ( xc_shadow_control(
                  xch, ctx->domid, XEN_DOMCTL_SHADOW_OP_CLEAN,
-                 HYPERCALL_BUFFER(to_send), ctx->save.p2m_size,
+                 HYPERCALL_BUFFER(dirty_bitmap), ctx->save.p2m_size,
                  NULL, 0, &stats) != ctx->save.p2m_size )
         {
             PERROR("Failed to retrieve logdirty bitmap");
@@ -527,7 +515,7 @@ static int send_domain_memory_live(struct xc_sr_context 
*ctx)
         if ( rc )
             goto out;
 
-        rc = send_some_pages(ctx, to_send, stats.dirty_count);
+        rc = send_some_pages(ctx, dirty_bitmap, stats.dirty_count);
         if ( rc )
             goto out;
     }
@@ -538,7 +526,7 @@ static int send_domain_memory_live(struct xc_sr_context 
*ctx)
 
     if ( xc_shadow_control(
              xch, ctx->domid, XEN_DOMCTL_SHADOW_OP_CLEAN,
-             HYPERCALL_BUFFER(to_send), ctx->save.p2m_size,
+             HYPERCALL_BUFFER(dirty_bitmap), ctx->save.p2m_size,
              NULL, 0, &stats) != ctx->save.p2m_size )
     {
         PERROR("Failed to retrieve logdirty bitmap");
@@ -550,9 +538,9 @@ static int send_domain_memory_live(struct xc_sr_context 
*ctx)
     if ( rc )
         goto out;
 
-    bitmap_or(to_send, ctx->save.deferred_pages, ctx->save.p2m_size);
+    bitmap_or(dirty_bitmap, ctx->save.deferred_pages, ctx->save.p2m_size);
 
-    rc = send_some_pages(ctx, to_send,
+    rc = send_some_pages(ctx, dirty_bitmap,
                          stats.dirty_count + ctx->save.nr_deferred_pages);
     if ( rc )
         goto out;
@@ -578,7 +566,7 @@ static int send_domain_memory_live(struct xc_sr_context 
*ctx)
 
         if ( xc_shadow_control(
                  xch, ctx->domid, XEN_DOMCTL_SHADOW_OP_PEEK,
-                 HYPERCALL_BUFFER(to_send), ctx->save.p2m_size,
+                 HYPERCALL_BUFFER(dirty_bitmap), ctx->save.p2m_size,
                  NULL, 0, &stats) != ctx->save.p2m_size )
         {
             PERROR("Failed to retrieve logdirty bitmap");
@@ -593,10 +581,6 @@ static int send_domain_memory_live(struct xc_sr_context 
*ctx)
   out:
     xc_set_progress_prefix(xch, NULL);
     free(progress_str);
-    xc_hypercall_buffer_free_pages(xch, to_send,
-                                   NRPAGES(bitmap_size(ctx->save.p2m_size)));
-    free(ctx->save.deferred_pages);
-    free(ctx->save.batch_pfns);
     return rc;
 }
 
@@ -609,17 +593,6 @@ static int send_domain_memory_nonlive(struct xc_sr_context 
*ctx)
     xc_interface *xch = ctx->xch;
     int rc = -1;
 
-    ctx->save.batch_pfns = malloc(MAX_BATCH_SIZE *
-                                  sizeof(*ctx->save.batch_pfns));
-    ctx->save.deferred_pages = calloc(1, bitmap_size(ctx->save.p2m_size));
-
-    if ( !ctx->save.batch_pfns || !ctx->save.deferred_pages )
-    {
-        PERROR("Failed to allocate memory for nonlive tracking structures");
-        errno = ENOMEM;
-        goto err;
-    }
-
     rc = suspend_domain(ctx);
     if ( rc )
         goto err;
@@ -631,9 +604,6 @@ static int send_domain_memory_nonlive(struct xc_sr_context 
*ctx)
         goto err;
 
  err:
-    free(ctx->save.deferred_pages);
-    free(ctx->save.batch_pfns);
-
     return rc;
 }
 
@@ -644,6 +614,23 @@ static int save(struct xc_sr_context *ctx, uint16_t 
guest_type)
 {
     xc_interface *xch = ctx->xch;
     int rc, saved_rc = 0, saved_errno = 0;
+    DECLARE_HYPERCALL_BUFFER_SHADOW(unsigned long, dirty_bitmap,
+                                    (&ctx->save.dirty_bitmap_hbuf));
+
+    dirty_bitmap = xc_hypercall_buffer_alloc_pages(
+                   xch, dirty_bitmap, 
NRPAGES(bitmap_size(ctx->save.p2m_size)));
+    ctx->save.batch_pfns = malloc(MAX_BATCH_SIZE *
+                                  sizeof(*ctx->save.batch_pfns));
+    ctx->save.deferred_pages = calloc(1, bitmap_size(ctx->save.p2m_size));
+
+    if ( !ctx->save.batch_pfns || !dirty_bitmap || !ctx->save.deferred_pages )
+    {
+        ERROR("Unable to allocate memory for dirty bitmaps, batch pfns and"
+              " deferred pages");
+        rc = -1;
+        errno = ENOMEM;
+        goto err;
+    }
 
     IPRINTF("Saving domain %d, type %s",
             ctx->domid, dhdr_type_to_str(guest_type));
@@ -704,6 +691,11 @@ static int save(struct xc_sr_context *ctx, uint16_t 
guest_type)
     if ( rc )
         PERROR("Failed to clean up");
 
+    xc_hypercall_buffer_free_pages(xch, dirty_bitmap,
+                                   NRPAGES(bitmap_size(ctx->save.p2m_size)));
+    free(ctx->save.deferred_pages);
+    free(ctx->save.batch_pfns);
+
     if ( saved_rc )
     {
         rc = saved_rc;
-- 
1.9.1


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