* [PATCH] xen/p2m: Fix one by off error in checking the P2M tree directory.
@ 2012-09-04 20:17 Konrad Rzeszutek Wilk
2012-09-04 20:44 ` Konrad Rzeszutek Wilk
0 siblings, 1 reply; 2+ messages in thread
From: Konrad Rzeszutek Wilk @ 2012-09-04 20:17 UTC (permalink / raw)
To: linux-kernel; +Cc: xen-devel, Konrad Rzeszutek Wilk
We would the full P2M top directory from 0->MAX_DOMAIN_PAGES (inclusive).
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:[<ffffffff819cadeb>]
(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
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
arch/x86/xen/p2m.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
index 0bfaf5b..af11f00 100644
--- a/arch/x86/xen/p2m.c
+++ b/arch/x86/xen/p2m.c
@@ -695,7 +695,7 @@ 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])
--
1.7.7.6
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] xen/p2m: Fix one by off error in checking the P2M tree directory.
2012-09-04 20:17 [PATCH] xen/p2m: Fix one by off error in checking the P2M tree directory Konrad Rzeszutek Wilk
@ 2012-09-04 20:44 ` Konrad Rzeszutek Wilk
0 siblings, 0 replies; 2+ messages in thread
From: Konrad Rzeszutek Wilk @ 2012-09-04 20:44 UTC (permalink / raw)
To: linux-kernel; +Cc: xen-devel
On Tue, Sep 04, 2012 at 04:17:14PM -0400, Konrad Rzeszutek Wilk wrote:
> We would the full P2M top directory from 0->MAX_DOMAIN_PAGES (inclusive).
.. 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:[<ffffffff819cadeb>]
> (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
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> ---
> arch/x86/xen/p2m.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/arch/x86/xen/p2m.c b/arch/x86/xen/p2m.c
> index 0bfaf5b..af11f00 100644
> --- a/arch/x86/xen/p2m.c
> +++ b/arch/x86/xen/p2m.c
> @@ -695,7 +695,7 @@ 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])
> --
> 1.7.7.6
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