x86/nmi/64: Make the "NMI executing" variable more consistent
Currently, "NMI executing" is one the first time an outermost
NMI hits repeat_nmi and zero thereafter. Change it to be zero
each time for consistency.
This is intended to help NMI handling fail harder if it's buggy.
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
index 0fb5252..5422bd2 100644
--- a/arch/x86/entry/entry_64.S
+++ b/arch/x86/entry/entry_64.S
@@ -1441,8 +1441,8 @@
/* Restore rdx. */
movq (%rsp), %rdx
- /* Set "NMI executing" on the stack. */
- pushq $1
+ /* Make room for "NMI executing". */
+ pushq $0
/* Leave room for the "iret" frame */
subq $(5*8), %rsp
@@ -1467,11 +1467,10 @@
* RSP is pointing to "outermost RIP". gsbase is unknown, but, if
* we're repeating an NMI, gsbase has the same value that it had on
* the first iteration. paranoid_entry will load the kernel
- * gsbase if needed before we call do_nmi.
- *
- * Set "NMI executing" in case we came back here via IRET.
+ * gsbase if needed before we call do_nmi. "NMI executing"
+ * is zero.
*/
- movq $1, 10*8(%rsp)
+ movq $1, 10*8(%rsp) /* Set "NMI executing". */
/*
* Copy the "outermost" frame to the "iret" frame. NMIs that nest