File xen.sr-restore-populate_pfns-pfns.patch of Package xen

From: Olaf Hering <olaf@aepfle.de>
Date: Fri, 23 Oct 2020 14:58:53 +0200
Subject: sr restore populate_pfns pfns

tools/guest: restore: move pfns array in populate_pfns

Remove allocation from hotpath, move populate_pfns' pfns array into preallocated space.
Use some prefix to avoid conflict with an array used in handle_page_data.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 tools/libs/guest/xg_sr_common.h  |  1 +
 tools/libs/guest/xg_sr_restore.c | 11 +----------
 2 files changed, 2 insertions(+), 10 deletions(-)

--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -223,24 +223,25 @@ struct xc_sr_save_arrays {
     void *guest_data[MAX_BATCH_SIZE];
 };
 
 struct xc_sr_restore_arrays {
     /* handle_page_data */
     xen_pfn_t pfns[MAX_BATCH_SIZE];
     uint32_t types[MAX_BATCH_SIZE];
     /* process_page_data */
     xen_pfn_t mfns[MAX_BATCH_SIZE];
     int map_errs[MAX_BATCH_SIZE];
     /* populate_pfns */
     xen_pfn_t pp_mfns[MAX_BATCH_SIZE];
+    xen_pfn_t pp_pfns[MAX_BATCH_SIZE];
 };
 
 struct xc_sr_context
 {
     xc_interface *xch;
     uint32_t domid;
     int fd;
 
     /* Plain VM, or checkpoints over time. */
     xc_stream_type_t stream_type;
 
     xc_dominfo_t dominfo;
--- a/tools/libs/guest/xg_sr_restore.c
+++ b/tools/libs/guest/xg_sr_restore.c
@@ -130,35 +130,28 @@ static int pfn_set_populated(struct xc_sr_context *ctx, xen_pfn_t pfn)
 }
 
 /*
  * Given a set of pfns, obtain memory from Xen to fill the physmap for the
  * unpopulated subset.  If types is NULL, no page type checking is performed
  * and all unpopulated pfns are populated.
  */
 int populate_pfns(struct xc_sr_context *ctx, unsigned int count,
                   const xen_pfn_t *original_pfns, const uint32_t *types)
 {
     xc_interface *xch = ctx->xch;
     xen_pfn_t *mfns = ctx->restore.m->pp_mfns,
-        *pfns = malloc(count * sizeof(*pfns));
+        *pfns = ctx->restore.m->pp_pfns;
     unsigned int i, nr_pfns = 0;
     int rc = -1;
 
-    if ( !pfns )
-    {
-        ERROR("Failed to allocate %zu bytes for populating the physmap",
-              2 * count * sizeof(*mfns));
-        goto err;
-    }
-
     for ( i = 0; i < count; ++i )
     {
         if ( (!types ||
               (types && page_type_has_stream_data(types[i]) == true)) &&
              !pfn_is_populated(ctx, original_pfns[i]) )
         {
             rc = pfn_set_populated(ctx, original_pfns[i]);
             if ( rc )
                 goto err;
             pfns[nr_pfns] = mfns[nr_pfns] = original_pfns[i];
             ++nr_pfns;
         }
@@ -181,26 +174,24 @@ int populate_pfns(struct xc_sr_context *ctx, unsigned int count,
                 ERROR("Populate physmap failed for pfn %u", i);
                 rc = -1;
                 goto err;
             }
 
             ctx->restore.ops.set_gfn(ctx, pfns[i], mfns[i]);
         }
     }
 
     rc = 0;
 
  err:
-    free(pfns);
-
     return rc;
 }
 
 /*
  * Given a list of pfns, their types, and a block of page data from the
  * stream, populate and record their types, map the relevant subset and copy
  * the data into the guest.
  */
 static int process_page_data(struct xc_sr_context *ctx, unsigned int count,
                              xen_pfn_t *pfns, uint32_t *types, void *page_data)
 {
     xc_interface *xch = ctx->xch;
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