linux/arch/x86
Dmitry Adamushko 280a9ca5d0 x86: fix resume (S2R) broken by Intel microcode module, on A110L
Impact: fix deadlock

This is in response to the following bug report:

Bug-Entry       : http://bugzilla.kernel.org/show_bug.cgi?id=12100
Subject         : resume (S2R) broken by Intel microcode module, on A110L
Submitter       : Andreas Mohr <andi@lisas.de>
Date            : 2008-11-25 08:48 (19 days old)
Handled-By      : Dmitry Adamushko <dmitry.adamushko@gmail.com>

[ The deadlock scenario has been discovered by Andreas Mohr ]

I think I might have a logical explanation why the system:

  (http://bugzilla.kernel.org/show_bug.cgi?id=12100)

might hang upon resuming, OTOH it should have likely hanged each and every time.

(1) possible deadlock in microcode_resume_cpu() if either 'if' section is
taken;

(2) now, I don't see it in spec. and can't experimentally verify it (newer
ucodes don't seem to be available for my Core2duo)... but logically-wise, I'd
think that when read upon resuming, the 'microcode revision' (MSR 0x8B) should
be back to its original one (we need to reload ucode anyway so it doesn't seem
logical if a cpu doesn't drop the version)... if so, the comparison with
memcmp() for the full 'struct cpu_signature' is wrong... and that's how one of
the aforementioned 'if' sections might have been triggered - leading to a
deadlock.

Obviously, in my tests I simulated loading/resuming with the ucode of the same
version (just to see that the file is loaded/re-loaded upon resuming) so this
issue has never popped up.

I'd appreciate if someone with an appropriate system might give a try to the
2nd patch (titled "fix a comparison && deadlock...").

In any case, the deadlock situation is a must-have fix.

Reported-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Tested-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>

Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-12-20 14:29:20 +01:00
..
boot x86: use limited register constraint for setnz 2008-11-25 15:38:03 +01:00
configs x86: remove irqbalance in kernel for 32 bit 2008-10-16 16:52:52 +02:00
crypto crypto: crc32c - Use Intel CRC32 instruction 2008-08-29 15:49:50 +10:00
ia32 compat: generic compat get/settimeofday 2008-10-16 11:21:33 -07:00
include/asm x86 Fix VMI crash on boot in 2.6.28-rc8 2008-12-14 16:24:38 -08:00
kernel x86: fix resume (S2R) broken by Intel microcode module, on A110L 2008-12-20 14:29:20 +01:00
kvm KVM: MMU: avoid creation of unreachable pages in the shadow 2008-11-26 12:34:27 +02:00
lguest lguest: fix irq vectors. 2008-10-31 11:24:28 +11:00
lib Merge branch 'x86/unify-cpu-detect' into x86-v28-for-linus-phase4-D 2008-10-11 20:23:20 +02:00
mach-default Merge branches 'x86/prototypes', 'x86/x2apic' and 'x86/debug' into x86/core 2008-08-14 14:58:22 +02:00
mach-generic x86: make 32bit support per_cpu vector 2008-10-16 16:52:53 +02:00
mach-rdc321x removed unused #include <linux/version.h>'s 2008-08-23 12:14:12 -07:00
mach-voyager x86, voyager: fix smp generic helper voyager breakage 2008-11-11 12:08:53 +01:00
math-emu
mm x86, hibernate: fix breakage on x86_32 with CONFIG_NUMA set 2008-11-12 23:28:51 +01:00
oprofile x86/oprofile: fix Intel cpu family 6 detection 2008-12-03 17:17:17 +01:00
pci x86: fixup config space size of CPU functions for AMD family 11h 2008-11-26 03:53:27 +01:00
power x86, hibernate: fix breakage on x86_32 with CONFIG_NUMA set 2008-11-12 23:28:51 +01:00
vdso Merge branches 'x86/urgent', 'x86/amd-iommu', 'x86/apic', 'x86/cleanups', 'x86/core', 'x86/cpu', 'x86/fixmap', 'x86/gart', 'x86/kprobes', 'x86/memtest', 'x86/modules', 'x86/nmi', 'x86/pat', 'x86/reboot', 'x86/setup', 'x86/step', 'x86/unify-pci', 'x86/uv', 'x86/xen' and 'xen-64bit' into x86/for-linus 2008-07-21 16:37:17 +02:00
video
xen Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-11-30 13:01:04 -08:00
Kconfig Merge branch 'x86/numa' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2008-11-19 18:53:02 -08:00
Kconfig.cpu x86, bts: improve help text for BTS config 2008-10-28 16:39:37 +01:00
Kconfig.debug x86: usb debug port early console, fix 2008-07-26 17:32:30 +02:00
Makefile x86, um: ... and asm-x86 move 2008-10-22 22:55:20 -07:00
Makefile_32.cpu x86: merge winchip-2 and winchip-2a cpu choices 2008-10-13 10:22:48 +02:00