x86/pti: Rename BUG_CPU_INSECURE to BUG_CPU_MELTDOWN

CVE-2017-5715 (Spectre v2 retpoline)

Use the name associated with the particular attack which needs page table
isolation for mitigation.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Cc: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
Cc: Jiri Koshina <jikos@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Lutomirski  <luto@amacapital.net>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Turner <pjt@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Greg KH <gregkh@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Kees Cook <keescook@google.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/alpine.DEB.2.20.1801051525300.1724@nanos

(backported from commit de791821)
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

arch/x86/include/asm/cpufeatures.h

@@ -293,6 +293,6 @@
 #define X86_BUG_SYSRET_SS_ATTRS	X86_BUG(8) /* SYSRET doesn't fix up SS attrs */
 
 #define X86_BUG_MONITOR		X86_BUG(12) /* IPI required to wake up remote CPU */
-#define X86_BUG_CPU_INSECURE		X86_BUG(14) /* CPU is insecure and needs kernel page table isolation */
+#define X86_BUG_CPU_MELTDOWN		X86_BUG(14) /* CPU is affected by meltdown attack and needs kernel page table isolation */
 
 #endif /* _ASM_X86_CPUFEATURES_H */

arch/x86/kernel/cpu/common.c

@@ -801,7 +801,7 @@ static void __init early_identify_cpu(struct cpuinfo_x86 *c)
 	setup_force_cpu_cap(X86_FEATURE_ALWAYS);
 
 	if (c->x86_vendor != X86_VENDOR_AMD)
-		setup_force_cpu_bug(X86_BUG_CPU_INSECURE);
+		setup_force_cpu_bug(X86_BUG_CPU_MELTDOWN);
 
 	fpu__init_system(c);
 }