x86/alternatives: Optimize optimize_nops()

JIRA: https://issues.redhat.com/browse/RHEL-68940

commit c3a3cb5
Author: Borislav Petkov (AMD) <bp@alien8.de>
Date:   Tue, 30 Jan 2024 11:59:40 +0100

    x86/alternatives: Optimize optimize_nops()

    Return early if NOPs have already been optimized.

    Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
    Link: https://lore.kernel.org/r/20240130105941.19707-4-bp@alien8.de

Signed-off-by: Waiman Long <longman@redhat.com>

Author: Waiman-Long

arch/x86/kernel/alternative.c

@@ -233,6 +233,10 @@ static void noinline optimize_nops(const u8 * const instr, u8 *buf, size_t len)
 		if (insn_is_nop(&insn)) {
 			int nop = i;
 
+			/* Has the NOP already been optimized? */
+			if (i + insn.length == len)
+				return;
+
 			next = skip_nops(buf, next, len);
 
 			add_nop(buf + nop, next - nop);