linux-kernel - Re: 2.6.32 stalls as guest in virtualbox

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <1264877041@msgid.manchmal.in-ulm.de>
Date:	Sat, 30 Jan 2010 19:46:24 +0100
From:	Christoph Biedl <linux-kernel.bfrz@...chmal.in-ulm.de>
To:	linux-kernel@...r.kernel.org
Subject: Re: 2.6.32 stalls as guest in virtualbox

Christoph Biedl wrote...

(...)

Christian Ehrhard gave me a lot of help understanding the kernel sides
of that issue, thanks for this.  Appearently virtualbox cannot
properly deal with the result of alternative_io in
arch/x86/include/asm/cmpxchg_32.h since this klugdy patch

--- a/arch/x86/include/asm/cmpxchg_32.h
+++ b/arch/x86/include/asm/cmpxchg_32.h
@@ -317,7 +317,7 @@ extern unsigned long long cmpxchg_486_u64(volatile void *, u64, u64);
        __typeof__(*(ptr)) __ret;                               \
        __typeof__(*(ptr)) __old = (o);                         \
        __typeof__(*(ptr)) __new = (n);                         \
-       alternative_io("call cmpxchg8b_emu",                    \
+       alternative_io("lock; cmpxchg8b (%%esi)",               \
                        "lock; cmpxchg8b (%%esi)" ,             \
                       X86_FEATURE_CX8,                         \
                       "=A" (__ret),                            \

fixes the problem, 

Unlike his findings described in
<http://marc.info/?l=linux-kernel&m=121545190107704&w=2>, the guest
does not crash but seems to run into a busy loop instead.

A acceptable workaround is selecting CONFIG_M686 (but not CONFIG_M586).

Now I guess this is rather something to virtualbox guys should take
care of, therefore I've opened a ticket there:
http://www.virtualbox.org/ticket/6100

    Christoph
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/