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authorThomas Renninger <trenn@suse.de>2011-12-04 22:17:29 +0100
committerLen Brown <len.brown@intel.com>2012-01-17 14:19:59 -0500
commit5c2a9f06a9cd7194f884cdc88144866235dec07d (patch)
tree226772f58c4a1727ff536913c69bab4b75f51427 /arch
parent95e3ec11491d0cbce9fcdf1cc17a527c114c7dcf (diff)
downloadlinux-linaro-stable-5c2a9f06a9cd7194f884cdc88144866235dec07d.tar.gz
intel idle: Make idle driver more robust
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][<ffffffff8143cf34>] ? cpuidle_idle_call+0xb4/0x340 [0.984807][<ffffffff8159e7bc>] ? __atomic_notifier_call_chain+0x4c/0x70 [0.984807][<ffffffff81001198>] ? cpu_idle+0x78/0xd0 Reference: https://bugzilla.novell.com/show_bug.cgi?id=726296 Cc: stable@vger.kernel.org Signed-off-by: Thomas Renninger <trenn@suse.de> CC: Bruno Friedmann <bruno@ioda-net.ch> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'arch')
0 files changed, 0 insertions, 0 deletions