x86/extable: Provide EX_TYPE_DEFAULT_MCE_SAFE and EX_TYPE_FAULT_MCE_SAFE

Provide exception fixup types which can be used to identify fixups which
allow in kernel #MC recovery and make them invoke the existing handlers.

These will be used at places where #MC recovery is handled correctly by the
caller.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/20210908132525.269689153@linutronix.de

arch/x86/include/asm/extable_fixup_types.h

@@ -16,4 +16,7 @@
 #define	EX_TYPE_WRMSR_IN_MCE		10
 #define	EX_TYPE_RDMSR_IN_MCE		11
 
+#define	EX_TYPE_DEFAULT_MCE_SAFE	12
+#define	EX_TYPE_FAULT_MCE_SAFE		13
+
 #endif

arch/x86/kernel/cpu/mce/severity.c

@@ -278,6 +278,8 @@ static int error_context(struct mce *m, struct pt_regs *regs)
 		m->kflags |= MCE_IN_KERNEL_COPYIN;
 		fallthrough;
 	case EX_TYPE_FAULT:
+	case EX_TYPE_FAULT_MCE_SAFE:
+	case EX_TYPE_DEFAULT_MCE_SAFE:
 		m->kflags |= MCE_IN_KERNEL_RECOV;
 		return IN_KERNEL_RECOV;
 	default:

arch/x86/mm/extable.c

@@ -131,8 +131,10 @@ int fixup_exception(struct pt_regs *regs, int trapnr, unsigned long error_code,
 
 	switch (e->type) {
 	case EX_TYPE_DEFAULT:
+	case EX_TYPE_DEFAULT_MCE_SAFE:
 		return ex_handler_default(e, regs);
 	case EX_TYPE_FAULT:
+	case EX_TYPE_FAULT_MCE_SAFE:
 		return ex_handler_fault(e, regs, trapnr);
 	case EX_TYPE_UACCESS:
 		return ex_handler_uaccess(e, regs, trapnr);