x86/bugs: Rename CONFIG_CPU_IBRS_ENTRY => CONFIG_MITIGATION_IBRS_ENTRY

Step 8/10 of the namespace unification of CPU mitigations related Kconfig options.

Suggested-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231121160740.1249350-9-leitao@debian.org

arch/x86/Kconfig

@@ -2561,7 +2561,7 @@ config MITIGATION_IBPB_ENTRY
 	help
 	  Compile the kernel with support for the retbleed=ibpb mitigation.
 
-config CPU_IBRS_ENTRY
+config MITIGATION_IBRS_ENTRY
 	bool "Enable IBRS on kernel entry"
 	depends on CPU_SUP_INTEL && X86_64
 	default y

arch/x86/entry/calling.h

@@ -303,7 +303,7 @@ For 32-bit we have the following conventions - kernel is built with
  * Assumes x86_spec_ctrl_{base,current} to have SPEC_CTRL_IBRS set.
  */
 .macro IBRS_ENTER save_reg
-#ifdef CONFIG_CPU_IBRS_ENTRY
+#ifdef CONFIG_MITIGATION_IBRS_ENTRY
 	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_KERNEL_IBRS
 	movl	$MSR_IA32_SPEC_CTRL, %ecx
 
@@ -332,7 +332,7 @@ For 32-bit we have the following conventions - kernel is built with
  * regs. Must be called after the last RET.
  */
 .macro IBRS_EXIT save_reg
-#ifdef CONFIG_CPU_IBRS_ENTRY
+#ifdef CONFIG_MITIGATION_IBRS_ENTRY
 	ALTERNATIVE "jmp .Lend_\@", "", X86_FEATURE_KERNEL_IBRS
 	movl	$MSR_IA32_SPEC_CTRL, %ecx
 

arch/x86/kernel/cpu/bugs.c

@@ -1439,7 +1439,7 @@ static enum spectre_v2_mitigation_cmd __init spectre_v2_parse_cmdline(void)
 		return SPECTRE_V2_CMD_AUTO;
 	}
 
-	if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_CPU_IBRS_ENTRY)) {
+	if (cmd == SPECTRE_V2_CMD_IBRS && !IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY)) {
 		pr_err("%s selected but not compiled in. Switching to AUTO select\n",
 		       mitigation_options[i].option);
 		return SPECTRE_V2_CMD_AUTO;
@@ -1565,7 +1565,7 @@ static void __init spectre_v2_select_mitigation(void)
 			break;
 		}
 
-		if (IS_ENABLED(CONFIG_CPU_IBRS_ENTRY) &&
+		if (IS_ENABLED(CONFIG_MITIGATION_IBRS_ENTRY) &&
 		    boot_cpu_has_bug(X86_BUG_RETBLEED) &&
 		    retbleed_cmd != RETBLEED_CMD_OFF &&
 		    retbleed_cmd != RETBLEED_CMD_STUFF &&