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Re: [Xen-devel] [PATCH v4 4/9] xen: introduce XEN_DOMCTL_devour

Hi Vitaly,

On 03/12/2014 17:16, Vitaly Kuznetsov wrote:
New operation sets the 'recipient' domain which will recieve all


memory pages from a particular domain and kills the original domain.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
@@ -1764,13 +1765,32 @@ void free_domheap_pages(struct page_info *pg, unsigned 
int order)


+        else
+        {
+            mfn = page_to_mfn(pg);
+            gmfn = mfn_to_gmfn(d, mfn);
+            page_set_owner(pg, NULL);
+            if ( assign_pages(d->recipient, pg, order, 0) )
+                /* assign_pages reports the error by itself */
+                goto out;
+            if ( guest_physmap_add_page(d->recipient, gmfn, mfn, order) )

On ARM, mfn_to_gmfn will always return the mfn. This would result to add a 1:1 mapping in the recipient domain.

But ... only DOM0 has its memory mapped 1:1. So this code may blow up the P2M of the recipient domain.

I'm not an x86 expert, but this may also happen when the recipient domain is using translated page mode (i.e HVM/PVHM).


Julien Grall

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