Borislav Petkov 6827d62a86 x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR ... [ Upstream commit e2def7d49d ] If an exception needs to be handled while reading an MSR - which is in most of the cases caused by a #GP on a non-existent MSR - then this is most likely the incarnation of a BIOS or a hardware bug. Such bug violates the architectural guarantee that MCA banks are present with all MSRs belonging to them. The proper fix belongs in the hardware/firmware - not in the kernel. Handling an #MC exception which is raised while an NMI is being handled would cause the nasty NMI nesting issue because of the shortcoming of IRET of reenabling NMIs when executed. And the machine is in an #MC context already so <Deity> be at its side. Tracing MSR accesses while in #MC is another no-no due to tracing being inherently a bad idea in atomic context: vmlinux.o: warning: objtool: do_machine_check()+0x4a: call to mce_rdmsrl() leaves .noinstr.text section so remove all that "additional" functionality from mce_rdmsrl() and provide it with a special exception handler which panics the machine when that MSR is not accessible. The exception handler prints a human-readable message explaining what the panic reason is but, what is more, it panics while in the #GP handler and latter won't have executed an IRET, thus opening the NMI nesting issue in the case when the #MC has happened while handling an NMI. (#MC itself won't be reenabled until MCG_STATUS hasn't been cleared). Suggested-by: Andy Lutomirski <luto@kernel.org> Suggested-by: Peter Zijlstra <peterz@infradead.org> [ Add missing prototypes for ex_handler_* ] Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> Reviewed-by: Tony Luck <tony.luck@intel.com> Link: https://lkml.kernel.org/r/20200906212130.GA28456@zn.tnic Signed-off-by: Sasha Levin <sashal@kernel.org>		2020-10-29 09:58:03 +01:00
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Makefile	…
amd.c	x86/mce/amd: Fix kobject lifetime	2020-02-28 17:22:18 +01:00
apei.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333	2019-06-05 17:37:06 +02:00
core.c	x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR	2020-10-29 09:58:03 +01:00
dev-mcelog.c	treewide: Add SPDX license identifier for missed files	2019-05-21 10:50:45 +02:00
genpool.c	treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 437	2019-06-05 17:37:17 +02:00
inject.c	x86/mce/inject: Fix a wrong assignment of i_mce.status	2020-08-19 08:15:53 +02:00
intel.c	x86/mce: Fix logic and comments around MSR_PPIN_CTL	2020-03-18 07:17:54 +01:00
internal.h	x86/mce: Make mce_rdmsrl() panic on an inaccessible MSR	2020-10-29 09:58:03 +01:00
p5.c	…
severity.c	x86/mce: Add Skylake quirk for patrol scrub reported errors	2020-10-29 09:58:01 +01:00
therm_throt.c	x86/mce: Lower throttling MCE messages' priority to warning	2019-12-31 16:44:09 +01:00
threshold.c	Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2018-12-26 17:03:51 -08:00
winchip.c	…