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Koen Kooi
189ce92b4c
Signed-off-by: Koen Kooi <koen@dominion.thruhere.net> Signed-off-by: Denys Dmytriyenko <denys@ti.com>
54 lines
1.9 KiB
Diff
54 lines
1.9 KiB
Diff
From 0e193a44b182c4d14fd4ec0eda63e1cba9e4a0a7 Mon Sep 17 00:00:00 2001
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From: Thomas Renninger <trenn@suse.de>
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Date: Sun, 4 Dec 2011 22:17:29 +0100
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Subject: [PATCH 098/129] intel idle: Make idle driver more robust
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commit 5c2a9f06a9cd7194f884cdc88144866235dec07d upstream.
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kvm -cpu host passes the original cpuid info to the guest.
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Latest kvm version seem to return true for mwait_leaf cpuid
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function on recent Intel CPUs. But it does not return mwait
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C-states (mwait_substates), instead zero is returned.
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While real CPUs seem to always return non-zero values, the intel
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idle driver should not get active in kvm (mwait_substates == 0)
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case and bail out.
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Otherwise a Null pointer exception will happen later when the
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cpuidle subsystem tries to get active:
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[0.984807] BUG: unable to handle kernel NULL pointer dereference at (null)
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[0.984807] IP: [<(null)>] (null)
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...
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[0.984807][<ffffffff8143cf34>] ? cpuidle_idle_call+0xb4/0x340
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[0.984807][<ffffffff8159e7bc>] ? __atomic_notifier_call_chain+0x4c/0x70
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[0.984807][<ffffffff81001198>] ? cpu_idle+0x78/0xd0
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Reference:
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https://bugzilla.novell.com/show_bug.cgi?id=726296
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Signed-off-by: Thomas Renninger <trenn@suse.de>
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CC: Bruno Friedmann <bruno@ioda-net.ch>
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Signed-off-by: Len Brown <len.brown@intel.com>
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Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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---
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drivers/idle/intel_idle.c | 3 ++-
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1 file changed, 2 insertions(+), 1 deletion(-)
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diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
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index 5d2f8e1..1dafcc3 100644
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--- a/drivers/idle/intel_idle.c
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+++ b/drivers/idle/intel_idle.c
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@@ -348,7 +348,8 @@ static int intel_idle_probe(void)
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cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &mwait_substates);
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if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
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- !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
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+ !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
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+ !mwait_substates)
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return -ENODEV;
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pr_debug(PREFIX "MWAIT substates: 0x%x\n", mwait_substates);
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--
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1.7.9.5
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