Revert "x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2" on v6.6 and older

This reverts commit a8c22ec36cdd99c1002d7152f859798fef7c4d58 which is
commit 98fdaeb upstream.

commit 7adb96687ce8 ("x86/bugs: Make spectre user default depend on
MITIGATION_SPECTRE_V2") depends on commit 72c70f4 ("x86/bugs: Add
a separate config for Spectre V2"), which introduced
MITIGATION_SPECTRE_V2.

commit 72c70f4 ("x86/bugs: Add a separate config for Spectre V2")
never landed in stable tree, thus, stable tree doesn't have
MITIGATION_SPECTRE_V2, that said, commit 7adb96687ce8 ("x86/bugs: Make
spectre user default depend on MITIGATION_SPECTRE_V2") has no value if
the dependecy was not applied.

Revert commit 7adb96687ce8 ("x86/bugs: Make spectre user default
depend on MITIGATION_SPECTRE_V2")  in stable kernel which landed in in
5.4.294, 5.10.238, 5.15.185, 6.1.141 and 6.6.93 stable versions.

Cc: David.Kaplan@amd.com
Cc: peterz@infradead.org
Cc: pawan.kumar.gupta@linux.intel.com
Cc: mingo@kernel.org
Cc: brad.spengler@opensrcsec.com
Cc: stable@vger.kernel.org # 6.6 6.1 5.15 5.10 5.4
Reported-by: Brad Spengler <brad.spengler@opensrcsec.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit a8b7347f5e752d51fc01ce0b63e1882fbde754f8)

FOF: 0825
Signed-off-by: Alok Tiwari <alok.a.tiwari@oracle.com>

Author: leitao

Documentation/admin-guide/kernel-parameters.txt

@@ -4718,8 +4718,6 @@
 
 			Selecting 'on' will also enable the mitigation
 			against user space to user space task attacks.
-			Selecting specific mitigation does not force enable
-			user mitigations.
 
 			Selecting 'off' will disable both the kernel and
 			the user space protections.

arch/x86/kernel/cpu/bugs.c

@@ -1686,13 +1686,9 @@ static enum spectre_v2_mitigation_cmd spectre_v2_cmd;
 static enum spectre_v2_user_cmd
 spectre_v2_parse_user_cmdline(void)
 {
-	enum spectre_v2_user_cmd mode;
 	char arg[20];
 	int ret, i;
 
-	mode = IS_ENABLED(CONFIG_MITIGATION_SPECTRE_V2) ?
-		SPECTRE_V2_USER_CMD_AUTO : SPECTRE_V2_USER_CMD_NONE;
-
 	switch (spectre_v2_cmd) {
 	case SPECTRE_V2_CMD_NONE:
 		return SPECTRE_V2_USER_CMD_NONE;
@@ -1705,7 +1701,7 @@ spectre_v2_parse_user_cmdline(void)
 	ret = cmdline_find_option(saved_command_line, "spectre_v2_user",
 				  arg, sizeof(arg));
 	if (ret < 0)
-		return mode;
+		return SPECTRE_V2_USER_CMD_AUTO;
 
 	for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) {
 		if (match_option(arg, ret, v2_user_options[i].option)) {
@@ -1715,8 +1711,8 @@ spectre_v2_parse_user_cmdline(void)
 		}
 	}
 
-	pr_err("Unknown user space protection option (%s). Switching to default\n", arg);
-	return mode;
+	pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg);
+	return SPECTRE_V2_USER_CMD_AUTO;
 }
 
 static inline bool spectre_v2_in_eibrs_mode(enum spectre_v2_mitigation mode)