xen/libxc-sr-save-types.patch

From: Olaf Hering <olaf@aepfle.de>
Date: Fri, 23 Oct 2020 11:23:51 +0200
Subject: libxc sr save types

tools: save: preallocate types array

Remove repeated allocation from migration loop. There will never be
more than MAX_BATCH_SIZE pages to process in a batch.
Allocate the space once.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 tools/libs/guest/xg_sr_common.h |  1 +
 tools/libs/guest/xg_sr_save.c   | 28 +++++++++++++---------------
 2 files changed, 14 insertions(+), 15 deletions(-)

--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -245,6 +245,7 @@ struct xc_sr_context
 
             xen_pfn_t *batch_pfns;
             xen_pfn_t *mfns;
+            xen_pfn_t *types;
             unsigned int nr_batch_pfns;
             unsigned long *deferred_pages;
             unsigned long nr_deferred_pages;
--- a/tools/libs/guest/xg_sr_save.c
+++ b/tools/libs/guest/xg_sr_save.c
@@ -88,7 +88,6 @@ static int write_checkpoint_record(struc
 static int write_batch(struct xc_sr_context *ctx)
 {
     xc_interface *xch = ctx->xch;
-    xen_pfn_t *types = NULL;
     void *guest_mapping = NULL;
     void **guest_data = NULL;
     void **local_pages = NULL;
@@ -105,8 +104,6 @@ static int write_batch(struct xc_sr_cont
 
     assert(nr_pfns != 0);
 
-    /* Types of the batch pfns. */
-    types = malloc(nr_pfns * sizeof(*types));
     /* Errors from attempting to map the gfns. */
     errors = malloc(nr_pfns * sizeof(*errors));
     /* Pointers to page data to send.  Mapped gfns or local allocations. */
@@ -116,7 +113,7 @@ static int write_batch(struct xc_sr_cont
     /* iovec[] for writev(). */
     iov = malloc((nr_pfns + 4) * sizeof(*iov));
 
-    if ( !types || !errors || !guest_data || !local_pages || !iov )
+    if ( !errors || !guest_data || !local_pages || !iov )
     {
         ERROR("Unable to allocate arrays for a batch of %u pages",
               nr_pfns);
@@ -125,7 +122,7 @@ static int write_batch(struct xc_sr_cont
 
     for ( i = 0; i < nr_pfns; ++i )
     {
-        types[i] = ctx->save.mfns[i] = ctx->save.ops.pfn_to_gfn(ctx,
+        ctx->save.types[i] = ctx->save.mfns[i] = ctx->save.ops.pfn_to_gfn(ctx,
                                                       ctx->save.batch_pfns[i]);
 
         /* Likely a ballooned page. */
@@ -136,7 +133,7 @@ static int write_batch(struct xc_sr_cont
         }
     }
 
-    rc = xc_get_pfn_type_batch(xch, ctx->domid, nr_pfns, types);
+    rc = xc_get_pfn_type_batch(xch, ctx->domid, nr_pfns, ctx->save.types);
     if ( rc )
     {
         PERROR("Failed to get types for pfn batch");
@@ -146,14 +143,14 @@ static int write_batch(struct xc_sr_cont
 
     for ( i = 0; i < nr_pfns; ++i )
     {
-        if ( !is_known_page_type(types[i]) )
+        if ( !is_known_page_type(ctx->save.types[i]) )
         {
             ERROR("Unknown type %#"PRIpfn" for pfn %#"PRIpfn,
-                  types[i], ctx->save.mfns[i]);
+                  ctx->save.types[i], ctx->save.mfns[i]);
             goto err;
         }
 
-        if ( !page_type_has_stream_data(types[i]) )
+        if ( !page_type_has_stream_data(ctx->save.types[i]) )
             continue;
 
         ctx->save.mfns[nr_pages++] = ctx->save.mfns[i];
@@ -172,7 +169,7 @@ static int write_batch(struct xc_sr_cont
 
         for ( i = 0, p = 0; i < nr_pfns; ++i )
         {
-            if ( !page_type_has_stream_data(types[i]) )
+            if ( !page_type_has_stream_data(ctx->save.types[i]) )
                 continue;
 
             if ( errors[p] )
@@ -183,7 +180,7 @@ static int write_batch(struct xc_sr_cont
             }
 
             orig_page = page = guest_mapping + (p * PAGE_SIZE);
-            rc = ctx->save.ops.normalise_page(ctx, types[i], &page);
+            rc = ctx->save.ops.normalise_page(ctx, ctx->save.types[i], &page);
 
             if ( orig_page != page )
                 local_pages[i] = page;
@@ -194,7 +191,7 @@ static int write_batch(struct xc_sr_cont
                 {
                     set_bit(ctx->save.batch_pfns[i], ctx->save.deferred_pages);
                     ++ctx->save.nr_deferred_pages;
-                    types[i] = XEN_DOMCTL_PFINFO_XTAB;
+                    ctx->save.types[i] = XEN_DOMCTL_PFINFO_XTAB;
                     --nr_pages;
                 }
                 else
@@ -223,7 +220,7 @@ static int write_batch(struct xc_sr_cont
     rec.length += nr_pages * PAGE_SIZE;
 
     for ( i = 0; i < nr_pfns; ++i )
-        rec_pfns[i] = ((uint64_t)(types[i]) << 32) | ctx->save.batch_pfns[i];
+        rec_pfns[i] = ((uint64_t)(ctx->save.types[i]) << 32) | ctx->save.batch_pfns[i];
 
     iov[0].iov_base = &rec.type;
     iov[0].iov_len = sizeof(rec.type);
@@ -275,7 +272,6 @@ static int write_batch(struct xc_sr_cont
     free(local_pages);
     free(guest_data);
     free(errors);
-    free(types);
 
     return rc;
 }
@@ -849,9 +845,10 @@ static int setup(struct xc_sr_context *c
     ctx->save.batch_pfns = malloc(MAX_BATCH_SIZE *
                                   sizeof(*ctx->save.batch_pfns));
     ctx->save.mfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.mfns));
+    ctx->save.types = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.types));
     ctx->save.deferred_pages = bitmap_alloc(ctx->save.p2m_size);
 
-    if ( !ctx->save.batch_pfns || !ctx->save.mfns ||
+    if ( !ctx->save.batch_pfns || !ctx->save.mfns || !ctx->save.types ||
          !dirty_bitmap || !ctx->save.deferred_pages )
     {
         ERROR("Unable to allocate memory for dirty bitmaps, batch pfns and"
@@ -883,6 +880,7 @@ static void cleanup(struct xc_sr_context
     xc_hypercall_buffer_free_pages(xch, dirty_bitmap,
                                    NRPAGES(bitmap_size(ctx->save.p2m_size)));
     free(ctx->save.deferred_pages);
+    free(ctx->save.types);
     free(ctx->save.mfns);
     free(ctx->save.batch_pfns);
 }