[1/3] xenoprof: adjust ordering of page sharing vs domain type setting

Commit Message

Jan Beulich April 15, 2020, 8:52 a.m. UTC

Buffer pages should be shared with "ignored" or "active" guests only
(besides, obviously, the primary profiling domain). Hence domain type
should be set to "ignored" before unsharing from the primary domain
(which implies even a previously "passive" domain may then access its
buffers, albeit that's not very useful unless it gets promoted to
"active" subsequently), i.e. such that no further writes of records to
the buffer would occur, and (at least for consistency) also before
sharing it (with the calling domain) from the XENOPROF_get_buffer path.

Signed-off-by: Jan Beulich <[e-mail]>
Reviewed-by: Wei Liu <[e-mail]>

Patch

--- a/xen/common/xenoprof.c
+++ b/xen/common/xenoprof.c
@@ -372,8 +372,8 @@  static void reset_passive(struct domain
     if ( x == NULL )
         return;
 
-    unshare_xenoprof_page_with_guest(x);
     x->domain_type = XENOPROF_DOMAIN_IGNORED;
+    unshare_xenoprof_page_with_guest(x);
 }
 
 static void reset_active_list(void)
@@ -654,6 +654,13 @@  static int xenoprof_op_get_buffer(XEN_GU
         if ( ret < 0 )
             return ret;
     }
+    else
+    {
+        d->xenoprof->domain_ready = 0;
+        d->xenoprof->domain_type = XENOPROF_DOMAIN_IGNORED;
+    }
+
+    d->xenoprof->is_primary = (xenoprof_primary_profiler == d);
 
     ret = share_xenoprof_page_with_guest(
         d, virt_to_mfn(d->xenoprof->rawbuf), d->xenoprof->npages);
@@ -662,10 +669,6 @@  static int xenoprof_op_get_buffer(XEN_GU
 
     xenoprof_reset_buf(d);
 
-    d->xenoprof->domain_type  = XENOPROF_DOMAIN_IGNORED;
-    d->xenoprof->domain_ready = 0;
-    d->xenoprof->is_primary   = (xenoprof_primary_profiler == current->domain);
-        
     xenoprof_get_buffer.nbuf = d->xenoprof->nbuf;
     xenoprof_get_buffer.bufsize = d->xenoprof->bufsize;
     if ( !paging_mode_translate(d) )