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x86/xen: correct bug in p2m list initialization 

Commit 054954eb05 ("xen: switch to
linear virtual mapped sparse p2m list") introduced an error.

During initialization of the p2m list a p2m identity area mapped by
a complete identity pmd entry has to be split up into smaller chunks
sometimes, if a non-identity pfn is introduced in this area.

If this non-identity pfn is not at index 0 of a p2m page the new
p2m page needed is initialized with wrong identity entries, as the
identity pfns don't start with the value corresponding to index 0,
but with the initial non-identity pfn. This results in weird wrong
mappings.

Correct the wrong initialization by starting with the correct pfn.

Cc: stable@vger.kernel.org # 3.19
Reported-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Tested-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
This commit is contained in:
Juergen Gross 2015-02-27 15:45:29 +01:00 committed by David Vrabel
parent 5054daa285
commit b8f05c8803
1 changed files with 1 additions and 1 deletions
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2
arch/x86/xen/p2m.c
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@ -563,7 +563,7 @@ static bool alloc_p2m(unsigned long pfn)
if (p2m_pfn == PFN_DOWN(__pa(p2m_missing)))
p2m_init(p2m);
else
p2m_init_identity(p2m, pfn);
p2m_init_identity(p2m, pfn & ~(P2M_PER_PAGE - 1));
spin_lock_irqsave(&p2m_update_lock, flags);