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

From: Olaf Hering <olaf@aepfle.de>
Date: Fri, 23 Oct 2020 14:36:45 +0200
Subject: sr restore pfns

tools/guest: restore: move pfns array

Remove allocation from hotpath, move pfns array into preallocated space.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 tools/libs/guest/xg_sr_common.h  | 2 ++
 tools/libs/guest/xg_sr_restore.c | 6 ++----
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -215,24 +215,26 @@ struct xc_sr_save_arrays {
     xen_pfn_t types[MAX_BATCH_SIZE];
     /* write_batch: Errors from attempting to map the gfns. */
     int errors[MAX_BATCH_SIZE];
     /* write_batch: iovec[] for writev(). */
     struct iovec iov[MAX_BATCH_SIZE + 4];
     /* write_batch */
     uint64_t rec_pfns[MAX_BATCH_SIZE];
     /* write_batch: Pointers to page data to send. Mapped gfns or local allocations. */
     void *guest_data[MAX_BATCH_SIZE];
 };
 
 struct xc_sr_restore_arrays {
+    /* handle_page_data */
+    xen_pfn_t 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
@@ -306,25 +306,25 @@ static int process_page_data(struct xc_sr_context *ctx, unsigned int count,
 
 /*
  * Validate a PAGE_DATA record from the stream, and pass the results to
  * process_page_data() to actually perform the legwork.
  */
 static int handle_page_data(struct xc_sr_context *ctx, struct xc_sr_record *rec)
 {
     xc_interface *xch = ctx->xch;
     struct xc_sr_rec_page_data_header *pages = rec->data;
     unsigned int i, pages_of_data = 0;
     int rc = -1;
 
-    xen_pfn_t *pfns = NULL, pfn;
+    xen_pfn_t *pfns = ctx->restore.m->pfns, pfn;
     uint32_t *types = NULL, type;
 
     /*
      * v2 compatibility only exists for x86 streams.  This is a bit of a
      * bodge, but it is less bad than duplicating handle_page_data() between
      * different architectures.
      */
 #if defined(__i386__) || defined(__x86_64__)
     /* v2 compat.  Infer the position of STATIC_DATA_END. */
     if ( ctx->restore.format_version < 3 && !ctx->restore.seen_static_data_end )
     {
         rc = handle_static_data_end(ctx);
@@ -354,27 +354,26 @@ static int handle_page_data(struct xc_sr_context *ctx, struct xc_sr_record *rec)
     {
         ERROR("Expected at least 1 pfn in PAGE_DATA record");
         goto err;
     }
 
     if ( rec->length < sizeof(*pages) + (pages->count * sizeof(uint64_t)) )
     {
         ERROR("PAGE_DATA record (length %u) too short to contain %u"
               " pfns worth of information", rec->length, pages->count);
         goto err;
     }
 
-    pfns = malloc(pages->count * sizeof(*pfns));
     types = malloc(pages->count * sizeof(*types));
-    if ( !pfns || !types )
+    if ( !types )
     {
         ERROR("Unable to allocate enough memory for %u pfns",
               pages->count);
         goto err;
     }
 
     for ( i = 0; i < pages->count; ++i )
     {
         pfn = pages->pfn[i] & PAGE_DATA_PFN_MASK;
         if ( !ctx->restore.ops.pfn_is_valid(ctx, pfn) )
         {
             ERROR("pfn %#"PRIpfn" (index %u) outside domain maximum", pfn, i);
@@ -403,25 +402,24 @@ static int handle_page_data(struct xc_sr_context *ctx, struct xc_sr_record *rec)
                          (PAGE_SIZE * pages_of_data)) )
     {
         ERROR("PAGE_DATA record wrong size: length %u, expected "
               "%zu + %zu + %lu", rec->length, sizeof(*pages),
               (sizeof(uint64_t) * pages->count), (PAGE_SIZE * pages_of_data));
         goto err;
     }
 
     rc = process_page_data(ctx, pages->count, pfns, types,
                            &pages->pfn[pages->count]);
  err:
     free(types);
-    free(pfns);
 
     return rc;
 }
 
 /*
  * Send checkpoint dirty pfn list to primary.
  */
 static int send_checkpoint_dirty_pfn_list(struct xc_sr_context *ctx)
 {
     xc_interface *xch = ctx->xch;
     int rc = -1;
     unsigned int count, written;