From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Message-Id: <20120528031216.518927759@decadent.org.uk> Date: Mon, 28 May 2012 04:13:41 +0100 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Andi Kleen , Andi Kleen , Tony Luck Subject: [ 099/117] MCE: Fix vm86 handling for 32bit mce handler In-Reply-To: <20120528031202.829379252@decadent.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andi Kleen commit a129a7c84582629741e5fa6f40026efcd7a65bd4 upstream. When running on 32bit the mce handler could misinterpret vm86 mode as ring 0. This can affect whether it does recovery or not; it was possible to panic when recovery was actually possible. Fix this by always forcing vm86 to look like ring 3. Signed-off-by: Andi Kleen Signed-off-by: Tony Luck Signed-off-by: Ben Hutchings --- arch/x86/kernel/cpu/mcheck/mce.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 66e1c51..5f793e6 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -437,6 +437,14 @@ static inline void mce_gather_info(struct mce *m, struct pt_regs *regs) if (m->mcgstatus & (MCG_STATUS_RIPV|MCG_STATUS_EIPV)) { m->ip = regs->ip; m->cs = regs->cs; + + /* + * When in VM86 mode make the cs look like ring 3 + * always. This is a lie, but it's better than passing + * the additional vm86 bit around everywhere. + */ + if (v8086_mode(regs)) + m->cs |= 3; } /* Use accurate RIP reporting if available. */ if (rip_msr)