x86/msr: Carry on after a non-"safe" MSR access fails

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This demotes an OOPS and likely panic due to a failed non-"safe" MSR
access to a WARN_ONCE() and, for RDMSR, a return value of zero.

To be clear, this type of failure should *not* happen.  This patch
exists to minimize the chance of nasty undebuggable failures
happening when a CONFIG_PARAVIRT=y bug in the non-"safe" MSR helpers
gets fixed.

Tested-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: KVM list <kvm@vger.kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: xen-devel <Xen-devel@lists.xen.org>
Link: http://lkml.kernel.org/r/26567b216aae70e795938f4b567eace5a0eb90ba.1459605520.git.luto@kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

...

This commit is contained in:

Andy Lutomirski 2016-04-02 07:01:37 -07:00 • committed by Ingo Molnar

parent c2ee03b2a9

commit fbd704374d

2 changed files with 35 additions and 2 deletions

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10

arch/x86/include/asm/msr.h

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27

arch/x86/mm/extable.c

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