From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 26 Jan 2012 16:45:33 +0200 From: "Kirill A. Shutemov" To: Greg KH Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Thomas Renninger , Bruno Friedmann , Len Brown Subject: Re: [67/90] intel idle: Make idle driver more robust Message-ID: <20120126144533.GA1731@shutemov.name> References: <20120123234211.GA19504@kroah.com> <20120123234028.628058547@clark.kroah.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8BIT In-Reply-To: <20120123234028.628058547@clark.kroah.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: On Mon, Jan 23, 2012 at 03:39:53PM -0800, Greg KH wrote: > 3.0-stable review patch. If anyone has any objections, please let me know. > > ------------------ > > From: Thomas Renninger > > commit 5c2a9f06a9cd7194f884cdc88144866235dec07d upstream. > > kvm -cpu host passes the original cpuid info to the guest. > > Latest kvm version seem to return true for mwait_leaf cpuid > function on recent Intel CPUs. But it does not return mwait > C-states (mwait_substates), instead zero is returned. > > While real CPUs seem to always return non-zero values, the intel > idle driver should not get active in kvm (mwait_substates == 0) > case and bail out. > Otherwise a Null pointer exception will happen later when the > cpuidle subsystem tries to get active: > [0.984807] BUG: unable to handle kernel NULL pointer dereference at (null) > [0.984807] IP: [<(null)>] (null) > ... > [0.984807][] ? cpuidle_idle_call+0xb4/0x340 > [0.984807][] ? __atomic_notifier_call_chain+0x4c/0x70 > [0.984807][] ? cpu_idle+0x78/0xd0 > > Reference: > https://bugzilla.novell.com/show_bug.cgi?id=726296 > > Signed-off-by: Thomas Renninger > CC: Bruno Friedmann > Signed-off-by: Len Brown > Signed-off-by: Greg Kroah-Hartman > > --- > drivers/idle/intel_idle.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > --- a/drivers/idle/intel_idle.c > +++ b/drivers/idle/intel_idle.c > @@ -321,7 +321,8 @@ static int intel_idle_probe(void) > cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates); > > if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || > - !(ecx & CPUID5_ECX_INTERRUPT_BREAK)) > + !(ecx & CPUID5_ECX_INTERRUPT_BREAK) || > + !mwait_substates) > return -ENODEV; It breaks build for me. >>From 4b26a35ab3bf4094efb31911587b676158f675b5 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Thu, 26 Jan 2012 16:24:50 +0200 Subject: [PATCH] intel_idle: fix build issue MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit CC drivers/idle/intel_idle.o /home/space/kas/git/public/linux-3.0-mid/drivers/idle/intel_idle.c: In function ‘intel_idle_probe’: /home/space/kas/git/public/linux-3.0-mid/drivers/idle/intel_idle.c:508:7: error: ‘mwait_substates’ undeclared (first use in this function) /home/space/kas/git/public/linux-3.0-mid/drivers/idle/intel_idle.c:508:7: note: each undeclared identifier is reported only once for each function it appears in make[3]: *** [drivers/idle/intel_idle.o] Error 1 Variable 'substates' hasn't renamed to 'mwait_substates' in 3.0. See c423628 intel_idle: delete substates DEBUG modparam Signed-off-by: Kirill A. Shutemov --- drivers/idle/intel_idle.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index 15d72ca..a1aecc3 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -505,7 +505,7 @@ static int intel_idle_probe(void) if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) || !(ecx & CPUID5_ECX_INTERRUPT_BREAK) || - !mwait_substates) + !substates) return -ENODEV; if (substates == 0) /* can over-ride via modparam */ -- Kirill A. Shutemov