From: Konrad Rzeszutek Wilk Date: Tue, 4 Sep 2012 19:45:17 +0000 (-0400) Subject: xen/p2m: Fix one-off error in checking the P2M tree directory. X-Git-Tag: Ubuntu-5.0.0-8.9~15347^2~4 X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=50e900417b8096939d12a46848f965e27a905e36;p=mirror_ubuntu-disco-kernel.git xen/p2m: Fix one-off error in checking the P2M tree directory. We would traverse the full P2M top directory (from 0->MAX_DOMAIN_PAGES inclusive) when trying to figure out whether we can re-use some of the P2M middle leafs. Which meant that if the kernel was compiled with MAX_DOMAIN_PAGES=512 we would try to use the 512th entry. Fortunately for us the p2m_top_index has a check for this: BUG_ON(pfn >= MAX_P2M_PFN); which we hit and saw this: (XEN) domain_crash_sync called from entry.S (XEN) Domain 0 (vcpu#0) crashed on cpu#0: (XEN) ----[ Xen-4.1.2-OVM x86_64 debug=n Tainted: C ]---- (XEN) CPU: 0 (XEN) RIP: e033:[] (XEN) RFLAGS: 0000000000000212 EM: 1 CONTEXT: pv guest (XEN) rax: ffffffff81db5000 rbx: ffffffff81db4000 rcx: 0000000000000000 (XEN) rdx: 0000000000480211 rsi: 0000000000000000 rdi: ffffffff81db4000 (XEN) rbp: ffffffff81793db8 rsp: ffffffff81793d38 r8: 0000000008000000 (XEN) r9: 4000000000000000 r10: 0000000000000000 r11: ffffffff81db7000 (XEN) r12: 0000000000000ff8 r13: ffffffff81df1ff8 r14: ffffffff81db6000 (XEN) r15: 0000000000000ff8 cr0: 000000008005003b cr4: 00000000000026f0 (XEN) cr3: 0000000661795000 cr2: 0000000000000000 Fixes-Oracle-Bug: 14570662 CC: stable@vger.kernel.org # only for v3.5 Signed-off-by: Konrad Rzeszutek Wilk --- diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c index d4b255463253..76ba0e97e530 100644 --- a/arch/x86/xen/p2m.c +++ b/arch/x86/xen/p2m.c @@ -599,7 +599,7 @@ bool __init early_can_reuse_p2m_middle(unsigned long set_pfn, unsigned long set_ if (p2m_index(set_pfn)) return false; - for (pfn = 0; pfn <= MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) { + for (pfn = 0; pfn < MAX_DOMAIN_PAGES; pfn += P2M_PER_PAGE) { topidx = p2m_top_index(pfn); if (!p2m_top[topidx])