x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation()

commit 53aadc525f61dba11b2fca3d8ac8d42323814763 upstream.

retbleed will depend on spectre_v2, while spectre_v2_user depends on
retbleed. Break this cycle.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 497562e78876599b9b2559ad182deb7203a640c8..74f81db135851c8cd16c7cbd0865bf5617e7058b 100644 (file)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -36,8 +36,9 @@
 #include "cpu.h"
 
 static void __init spectre_v1_select_mitigation(void);
-static void __init retbleed_select_mitigation(void);
 static void __init spectre_v2_select_mitigation(void);
+static void __init retbleed_select_mitigation(void);
+static void __init spectre_v2_user_select_mitigation(void);
 static void __init ssb_select_mitigation(void);
 static void __init l1tf_select_mitigation(void);
 static void __init mds_select_mitigation(void);
@@ -136,13 +137,19 @@ void __init check_bugs(void)
 
        /* Select the proper CPU mitigations before patching alternatives: */
        spectre_v1_select_mitigation();
+       spectre_v2_select_mitigation();
+       /*
+        * retbleed_select_mitigation() relies on the state set by
+        * spectre_v2_select_mitigation(); specifically it wants to know about
+        * spectre_v2=ibrs.
+        */
        retbleed_select_mitigation();
        /*
-        * spectre_v2_select_mitigation() relies on the state set by
+        * spectre_v2_user_select_mitigation() relies on the state set by
         * retbleed_select_mitigation(); specifically the STIBP selection is
         * forced for UNRET.
         */
-       spectre_v2_select_mitigation();
+       spectre_v2_user_select_mitigation();
        ssb_select_mitigation();
        l1tf_select_mitigation();
        md_clear_select_mitigation();
@@ -918,13 +925,15 @@ static void __init spec_v2_user_print_cond(const char *reason, bool secure)
                pr_info("spectre_v2_user=%s forced on command line.\n", reason);
 }
 
+static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd;
+
 static enum spectre_v2_user_cmd __init
-spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd)
+spectre_v2_parse_user_cmdline(void)
 {
        char arg[20];
        int ret, i;
 
-       switch (v2_cmd) {
+       switch (spectre_v2_cmd) {
        case SPECTRE_V2_CMD_NONE:
                return SPECTRE_V2_USER_CMD_NONE;
        case SPECTRE_V2_CMD_FORCE:
@@ -959,7 +968,7 @@ static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode)
 }
 
 static void __init
-spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
+spectre_v2_user_select_mitigation(void)
 {
        enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
        bool smt_possible = IS_ENABLED(CONFIG_SMP);
@@ -972,7 +981,7 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
            cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
                smt_possible = false;
 
-       cmd = spectre_v2_parse_user_cmdline(v2_cmd);
+       cmd = spectre_v2_parse_user_cmdline();
        switch (cmd) {
        case SPECTRE_V2_USER_CMD_NONE:
                goto set_mode;
@@ -1289,7 +1298,7 @@ static void __init spectre_v2_select_mitigation(void)
        }
 
        /* Set up IBPB and STIBP depending on the general spectre V2 command */
-       spectre_v2_user_select_mitigation(cmd);
+       spectre_v2_cmd = cmd;
 }
 
 static void update_stibp_msr(void * __unused)