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Re: [Xen-devel] [PATCH v6 COLO 06/15] libxc/save: support COLO save





On 06/08/2015 09:04 PM, Andrew Cooper wrote:
On 08/06/15 04:45, Yang Hongyang wrote:
call callbacks->get_dirty_pfn() after suspend primary vm to
get dirty pages on secondary vm, and send pages both dirty on
primary/secondary to secondary.

Signed-off-by: Yang Hongyang <yanghy@xxxxxxxxxxxxxx>
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
CC: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
  tools/libxc/xc_sr_save.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++-
  1 file changed, 48 insertions(+), 1 deletion(-)

diff --git a/tools/libxc/xc_sr_save.c b/tools/libxc/xc_sr_save.c
index d63b783..cda61ed 100644
--- a/tools/libxc/xc_sr_save.c
+++ b/tools/libxc/xc_sr_save.c
@@ -515,6 +515,31 @@ static int send_memory_live(struct xc_sr_context *ctx)
      return rc;
  }

+static int update_dirty_bitmap(uint8_t *(*get_dirty_pfn)(void *), void *data,
+                               unsigned long p2m_size, unsigned long *bitmap)

This function should take a ctx rather than having the caller expand 3
parameters.  Also, "update_dirty_bitmap" is a little misleading, as it
isn't querying the hypervisor for the dirty bitmap.

how about merge_secondary_dirty_bitmap()?


+{
+    uint64_t *pfn_list;
+    uint64_t count, i;
+    uint64_t pfn;
+
+    pfn_list = (uint64_t *)get_dirty_pfn(data);

This looks like a recipe for width-errors.  The get_dirty_pfn() call
should take a pointer to a struct for it to fill.

+    assert(pfn_list);

This should turn into an error rather than an abort().

+
+    count = pfn_list[0];
+    for (i = 0; i < count; i++) {

style

+        pfn = pfn_list[i + 1];
+        if (pfn > p2m_size) {
+            errno = EINVAL;
+            return -1;
+        }
+
+        set_bit(pfn, bitmap);
+    }
+
+    free(pfn_list);
+    return 0;
+}
+
  /*
   * Suspend the domain and send dirty memory.
   * This is the last iteration of the live migration and the
@@ -555,6 +580,19 @@ static int suspend_and_send_dirty(struct xc_sr_context 
*ctx)

      bitmap_or(dirty_bitmap, ctx->save.deferred_pages, ctx->save.p2m_size);

+    if ( !ctx->save.live && ctx->save.callbacks->get_dirty_pfn )
+    {

Shouldn't get_dirty_pfn be mandatory for COLO streams (even if it is a
noop to start with) ?

~Andrew

+        rc = update_dirty_bitmap(ctx->save.callbacks->get_dirty_pfn,
+                                 ctx->save.callbacks->data,
+                                 ctx->save.p2m_size,
+                                 dirty_bitmap);
+        if ( rc )
+        {
+            PERROR("Failed to get secondary vm's dirty pages");
+            goto out;
+        }
+    }
+
      rc = send_dirty_pages(ctx, stats.dirty_count + 
ctx->save.nr_deferred_pages);
      if ( rc )
          goto out;
@@ -784,7 +822,16 @@ static int save(struct xc_sr_context *ctx, uint16_t 
guest_type)
              if ( rc )
                  goto err;

-            ctx->save.callbacks->postcopy(ctx->save.callbacks->data);
+            rc = ctx->save.callbacks->postcopy(ctx->save.callbacks->data);
+            if ( !rc ) {
+                if ( !errno )
+                {
+                    /* Postcopy request failed (without errno, using EINVAL) */
+                    errno = EINVAL;
+                }
+                rc = -1;
+                goto err;
+            }

              rc = ctx->save.callbacks->checkpoint(ctx->save.callbacks->data);
              if ( rc <= 0 )

.


--
Thanks,
Yang.

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