x86/entry, nmi: Disable #DB

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Instead of playing stupid games with IST stacks, fully disallow #DB
during NMIs. There is absolutely no reason to allow them, and killing
this saves a heap of trouble.

#DB is already forbidden on noinstr and CEA, so there can't be a #DB before
this. Disabling it right after nmi_enter() ensures that the full NMI code
is protected.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/20200529213321.069223695@infradead.org

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Peter Zijlstra 2020-05-29 23:27:34 +02:00 • committed by Thomas Gleixner

parent e1de11d4d1

commit fd338e3564

1 changed files with 3 additions and 52 deletions

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arch/x86/kernel/nmi.c

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