arm64: Handle serror in NMI context

Per definition of the daifflags, Serrors can occur during any interrupt
context, that includes NMI contexts. Trying to nmi_enter in an nmi context
will crash.

Skip nmi_enter/nmi_exit when serror occurred during an NMI.

Suggested-by: James Morse <james.morse@arm.com>
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Dave Martin <dave.martin@arm.com>
Cc: James Morse <james.morse@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

diff --git a/arch/arm64/kernel/traps.c b/arch/arm64/kernel/traps.c
index 4e2fb87..8ad119c 100644 (file)
--- a/arch/arm64/kernel/traps.c
+++ b/arch/arm64/kernel/traps.c
@@ -898,13 +898,17 @@ bool arm64_is_fatal_ras_serror(struct pt_regs *regs, unsigned int esr)
 
 asmlinkage void do_serror(struct pt_regs *regs, unsigned int esr)
 {
-       nmi_enter();
+       const bool was_in_nmi = in_nmi();
+
+       if (!was_in_nmi)
+               nmi_enter();
 
        /* non-RAS errors are not containable */
        if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(regs, esr))
                arm64_serror_panic(regs, esr);
 
-       nmi_exit();
+       if (!was_in_nmi)
+               nmi_exit();
 }
 
 void __pte_error(const char *file, int line, unsigned long val)