File xen.sr-save-guest_data.patch of Package xen

Overview Repositories Revisions Requests Users Attributes Meta

File xen.sr-save-guest_data.patch of Package xen

From: Olaf Hering <olaf@aepfle.de>
Date: Fri, 23 Oct 2020 11:40:45 +0200
Subject: sr save guest_data

tools: save: preallocate guest_data 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.

Because this was allocated with calloc:
Adjust the loop to clear unused entries as needed.

Signed-off-by: Olaf Hering <olaf@aepfle.de>
---
 tools/libs/guest/xg_sr_common.h |  1 +
 tools/libs/guest/xg_sr_save.c   | 20 +++++----
 2 files changed, 12 insertions(+), 9 deletions(-)

--- a/tools/libs/guest/xg_sr_common.h
+++ b/tools/libs/guest/xg_sr_common.h
@@ -240,24 +240,25 @@ struct xc_sr_context
             unsigned long p2m_size;
             size_t pages_sent;
             size_t overhead_sent;
 
             struct precopy_stats stats;
 
             xen_pfn_t *batch_pfns;
             xen_pfn_t *mfns;
             xen_pfn_t *types;
             int *errors;
             struct iovec *iov;
             uint64_t *rec_pfns;
+            void **guest_data;
             unsigned int nr_batch_pfns;
             unsigned long *deferred_pages;
             unsigned long nr_deferred_pages;
             xc_hypercall_buffer_t dirty_bitmap_hbuf;
         } save;
 
         struct /* Restore data. */
         {
             struct xc_sr_restore_ops ops;
             struct restore_callbacks *callbacks;
 
             int send_back_fd;
--- a/tools/libs/guest/xg_sr_save.c
+++ b/tools/libs/guest/xg_sr_save.c
@@ -80,44 +80,41 @@ static int write_checkpoint_record(struct xc_sr_context *ctx)
  * is constructed in ctx->save.batch_pfns.
  *
  * This function:
  * - gets the types for each pfn in the batch.
  * - for each pfn with real data:
  *   - maps and attempts to localise the pages.
  * - construct and writes a PAGE_DATA record into the stream.
  */
 static int write_batch(struct xc_sr_context *ctx)
 {
     xc_interface *xch = ctx->xch;
     void *guest_mapping = NULL;
-    void **guest_data = NULL;
     void **local_pages = NULL;
     int rc = -1;
     unsigned int i, p, nr_pages = 0, nr_pages_mapped = 0;
     unsigned int nr_pfns = ctx->save.nr_batch_pfns;
     void *page, *orig_page;
     int iovcnt = 0;
     struct xc_sr_rec_page_data_header hdr = { 0 };
     struct xc_sr_record rec = {
         .type = REC_TYPE_PAGE_DATA,
     };
 
     assert(nr_pfns != 0);
 
-    /* Pointers to page data to send.  Mapped gfns or local allocations. */
-    guest_data = calloc(nr_pfns, sizeof(*guest_data));
     /* Pointers to locally allocated pages.  Need freeing. */
     local_pages = calloc(nr_pfns, sizeof(*local_pages));
 
-    if ( !guest_data || !local_pages )
+    if ( !local_pages )
     {
         ERROR("Unable to allocate arrays for a batch of %u pages",
               nr_pfns);
         goto err;
     }
 
     for ( i = 0; i < nr_pfns; ++i )
     {
         ctx->save.types[i] = ctx->save.mfns[i] = ctx->save.ops.pfn_to_gfn(ctx,
                                                       ctx->save.batch_pfns[i]);
 
         /* Likely a ballooned page. */
@@ -156,54 +153,58 @@ static int write_batch(struct xc_sr_context *ctx)
         guest_mapping = xenforeignmemory_map(xch->fmem, ctx->domid, PROT_READ,
             nr_pages, ctx->save.mfns, ctx->save.errors);
         if ( !guest_mapping )
         {
             PERROR("Failed to map guest pages");
             goto err;
         }
         nr_pages_mapped = nr_pages;
 
         for ( i = 0, p = 0; i < nr_pfns; ++i )
         {
             if ( !page_type_has_stream_data(ctx->save.types[i]) )
+            {
+                ctx->save.guest_data[i] = NULL;
                 continue;
+            }
 
             if ( ctx->save.errors[p] )
             {
                 ERROR("Mapping of pfn %#"PRIpfn" (mfn %#"PRIpfn") failed %d",
                       ctx->save.batch_pfns[i], ctx->save.mfns[p],
                       ctx->save.errors[p]);
                 goto err;
             }
 
             orig_page = page = guest_mapping + (p * PAGE_SIZE);
             rc = ctx->save.ops.normalise_page(ctx, ctx->save.types[i], &page);
 
             if ( orig_page != page )
                 local_pages[i] = page;
 
             if ( rc )
             {
+                ctx->save.guest_data[i] = NULL;
                 if ( rc == -1 && errno == EAGAIN )
                 {
                     set_bit(ctx->save.batch_pfns[i], ctx->save.deferred_pages);
                     ++ctx->save.nr_deferred_pages;
                     ctx->save.types[i] = XEN_DOMCTL_PFINFO_XTAB;
                     --nr_pages;
                 }
                 else
                     goto err;
             }
             else
-                guest_data[i] = page;
+                ctx->save.guest_data[i] = page;
 
             rc = -1;
             ++p;
         }
     }
 
     hdr.count = nr_pfns;
 
     rec.length = sizeof(hdr);
     rec.length += nr_pfns * sizeof(*ctx->save.rec_pfns);
     rec.length += nr_pages * PAGE_SIZE;
 
@@ -223,51 +224,50 @@ static int write_batch(struct xc_sr_context *ctx)
     ctx->save.iov[3].iov_base = ctx->save.rec_pfns;
     ctx->save.iov[3].iov_len = nr_pfns * sizeof(*ctx->save.rec_pfns);
 
     iovcnt = 4;
     ctx->save.pages_sent += nr_pages;
     ctx->save.overhead_sent += sizeof(rec) + sizeof(hdr) +
                                nr_pfns * sizeof(*ctx->save.rec_pfns);
 
     if ( nr_pages )
     {
         for ( i = 0; i < nr_pfns; ++i )
         {
-            if ( guest_data[i] )
+            if ( ctx->save.guest_data[i] )
             {
-                ctx->save.iov[iovcnt].iov_base = guest_data[i];
+                ctx->save.iov[iovcnt].iov_base = ctx->save.guest_data[i];
                 ctx->save.iov[iovcnt].iov_len = PAGE_SIZE;
                 iovcnt++;
                 --nr_pages;
             }
         }
     }
 
     if ( writev_exact(ctx->fd, ctx->save.iov, iovcnt) )
     {
         PERROR("Failed to write page data to stream");
         goto err;
     }
 
     /* Sanity check we have sent all the pages we expected to. */
     assert(nr_pages == 0);
     rc = ctx->save.nr_batch_pfns = 0;
 
  err:
     if ( guest_mapping )
         xenforeignmemory_unmap(xch->fmem, guest_mapping, nr_pages_mapped);
     for ( i = 0; local_pages && i < nr_pfns; ++i )
         free(local_pages[i]);
     free(local_pages);
-    free(guest_data);
 
     return rc;
 }
 
 /*
  * Flush a batch of pfns into the stream.
  */
 static int flush_batch(struct xc_sr_context *ctx)
 {
     int rc = 0;
 
     if ( ctx->save.nr_batch_pfns == 0 )
@@ -827,29 +827,30 @@ static int setup(struct xc_sr_context *ctx)
     if ( rc )
         goto err;
 
     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.mfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.mfns));
     ctx->save.types = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.types));
     ctx->save.errors = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.errors));
     ctx->save.iov = malloc((4 + MAX_BATCH_SIZE) * sizeof(*ctx->save.iov));
     ctx->save.rec_pfns = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.rec_pfns));
+    ctx->save.guest_data = malloc(MAX_BATCH_SIZE * sizeof(*ctx->save.guest_data));
     ctx->save.deferred_pages = bitmap_alloc(ctx->save.p2m_size);
 
     if ( !ctx->save.batch_pfns || !ctx->save.mfns || !ctx->save.types ||
          !ctx->save.errors || !ctx->save.iov || !ctx->save.rec_pfns ||
-         !dirty_bitmap || !ctx->save.deferred_pages )
+         !ctx->save.guest_data ||!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;
     }
 
     rc = 0;
 
  err:
     return rc;
@@ -862,24 +863,25 @@ static void cleanup(struct xc_sr_context *ctx)
                                     &ctx->save.dirty_bitmap_hbuf);
 
 
     xc_shadow_control(xch, ctx->domid, XEN_DOMCTL_SHADOW_OP_OFF,
                       NULL, 0);
 
     if ( ctx->save.ops.cleanup(ctx) )
         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.guest_data);
     free(ctx->save.rec_pfns);
     free(ctx->save.iov);
     free(ctx->save.errors);
     free(ctx->save.types);
     free(ctx->save.mfns);
     free(ctx->save.batch_pfns);
 }
 
 /*
  * Save a domain.
  */
 static int save(struct xc_sr_context *ctx, uint16_t guest_type)

Places

File xen.sr-save-guest_data.patch of Package xen

Places