[Xen-devel] [PATCH] xenpaging: check p2mt in p2m_mem_paging functions

[Olaf Hering <olaf@xxxxxxxxx>]

# HG changeset patch
# User Olaf Hering <olaf@xxxxxxxxx>
# Date 1318336928 -7200
# Node ID bc64a435d572680efb221445c28583d03d4eb175
# Parent  bdd49540f1e1c803d01c88adb67c6ce01e2d00d8
xenpaging: check p2mt in p2m_mem_paging functions

Add checks to forward the p2m_ram_paging* state properly during page-in.

Resume can be called several times if several vcpus called populate for
the gfn. Finish resume only once and print some debug for other cases.

Signed-off-by: Olaf Hering <olaf@xxxxxxxxx>

diff -r bdd49540f1e1 -r bc64a435d572 xen/arch/x86/mm/p2m.c
--- a/xen/arch/x86/mm/p2m.c
+++ b/xen/arch/x86/mm/p2m.c
@@ -852,16 +852,22 @@ int p2m_mem_paging_prep(struct domain *d
     p2m_access_t a;
     mfn_t mfn;
     struct p2m_domain *p2m = p2m_get_hostp2m(d);
-    int ret = -ENOMEM;
+    int ret;
 
     p2m_lock(p2m);
 
     mfn = p2m->get_entry(p2m, gfn, &p2mt, &a, p2m_query, NULL);
 
+    ret = -ENOENT;
+    /* Allow only missing pages */
+    if ( p2mt != p2m_ram_paging_in_start )
+        goto out;
+
     /* Allocate a page if the gfn does not have one yet */
     if ( !mfn_valid(mfn) )
     {
         /* Get a free page */
+        ret = -ENOMEM;
         page = alloc_domheap_page(p2m->domain, 0);
         if ( unlikely(page == NULL) )
             goto out;
@@ -897,9 +903,16 @@ void p2m_mem_paging_resume(struct domain
     {
         p2m_lock(p2m);
         mfn = p2m->get_entry(p2m, rsp.gfn, &p2mt, &a, p2m_query, NULL);
-        set_p2m_entry(p2m, rsp.gfn, mfn, 0, p2m_ram_rw, a);
-        set_gpfn_from_mfn(mfn_x(mfn), rsp.gfn);
-        audit_p2m(p2m, 1);
+        /* Allow only pages which were prepared properly or pages which were 
nominated but not evicted */
+        if ( mfn_valid(mfn) && ( p2mt == p2m_ram_paging_in  || p2mt == 
p2m_ram_paging_in_start ) )
+        {
+            set_p2m_entry(p2m, rsp.gfn, mfn, 0, p2m_ram_rw, a);
+            set_gpfn_from_mfn(mfn_x(mfn), rsp.gfn);
+            audit_p2m(p2m, 1);
+        /* May be called more than once if the gfn was populate from different 
vcpus */
+        } else if ( p2mt != p2m_ram_rw ) {
+            printk("resume: %d %lx %x %lx\n", d->domain_id, rsp.gfn, p2mt, 
mfn_x(mfn));
+        }
         p2m_unlock(p2m);
     }
 

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