From: Juergen Gross Date: Fri, 27 Feb 2015 14:45:29 +0000 (+0100) Subject: x86/xen: correct bug in p2m list initialization X-Git-Tag: v3.19.3~38 X-Git-Url: http://git.hungrycats.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3d60a2bc53f2ba4c4bcf889d0c10841c4c702bac;p=linux x86/xen: correct bug in p2m list initialization commit b8f05c8803fce899d79ca66f8d7f348cf15fb40e upstream. Commit 054954eb051f35e74b75a566a96fe756015352c8 ("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. Reported-by: Stefan Bader Signed-off-by: Juergen Gross Tested-by: Stefan Bader Signed-off-by: David Vrabel Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index 376a0a9dc670..cc45a9f1a6e6 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -567,7 +567,7 @@ 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);