git.ipfire.org Git - thirdparty/kernel/stable-queue.git/blob

   1 From foo@baz Tue Jul 12 05:07:35 PM CEST 2022
   2 From: Peter Zijlstra <peterz@infradead.org>
   3 Date: Tue, 14 Jun 2022 23:15:56 +0200
   4 Subject: x86/bugs: Split spectre_v2_select_mitigation() and spectre_v2_user_select_mitigation()
   5
   6 From: Peter Zijlstra <peterz@infradead.org>
   7
   8 commit 166115c08a9b0b846b783088808a27d739be6e8d upstream.
   9
  10 retbleed will depend on spectre_v2, while spectre_v2_user depends on
  11 retbleed. Break this cycle.
  12
  13 Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
  14 Signed-off-by: Borislav Petkov <bp@suse.de>
  15 Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
  16 Signed-off-by: Borislav Petkov <bp@suse.de>
  17 Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
  18 Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
  19 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  20 ---
  21  arch/x86/kernel/cpu/bugs.c |   25 +++++++++++++++++--------
  22  1 file changed, 17 insertions(+), 8 deletions(-)
  23
  24 --- a/arch/x86/kernel/cpu/bugs.c
  25 +++ b/arch/x86/kernel/cpu/bugs.c
  26 @@ -37,8 +37,9 @@
  27  #include "cpu.h"
  28
  29  static void __init spectre_v1_select_mitigation(void);
  30 -static void __init retbleed_select_mitigation(void);
  31  static void __init spectre_v2_select_mitigation(void);
  32 +static void __init retbleed_select_mitigation(void);
  33 +static void __init spectre_v2_user_select_mitigation(void);
  34  static void __init ssb_select_mitigation(void);
  35  static void __init l1tf_select_mitigation(void);
  36  static void __init mds_select_mitigation(void);
  37 @@ -137,13 +138,19 @@ void __init check_bugs(void)
  38
  39         /* Select the proper CPU mitigations before patching alternatives: */
  40         spectre_v1_select_mitigation();
  41 +       spectre_v2_select_mitigation();
  42 +       /*
  43 +        * retbleed_select_mitigation() relies on the state set by
  44 +        * spectre_v2_select_mitigation(); specifically it wants to know about
  45 +        * spectre_v2=ibrs.
  46 +        */
  47         retbleed_select_mitigation();
  48         /*
  49 -        * spectre_v2_select_mitigation() relies on the state set by
  50 +        * spectre_v2_user_select_mitigation() relies on the state set by
  51          * retbleed_select_mitigation(); specifically the STIBP selection is
  52          * forced for UNRET.
  53          */
  54 -       spectre_v2_select_mitigation();
  55 +       spectre_v2_user_select_mitigation();
  56         ssb_select_mitigation();
  57         l1tf_select_mitigation();
  58         md_clear_select_mitigation();
  59 @@ -969,13 +976,15 @@ static void __init spec_v2_user_print_co
  60                 pr_info("spectre_v2_user=%s forced on command line.\n", reason);
  61  }
  62
  63 +static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd;
  64 +
  65  static enum spectre_v2_user_cmd __init
  66 -spectre_v2_parse_user_cmdline(enum spectre_v2_mitigation_cmd v2_cmd)
  67 +spectre_v2_parse_user_cmdline(void)
  68  {
  69         char arg[20];
  70         int ret, i;
  71
  72 -       switch (v2_cmd) {
  73 +       switch (spectre_v2_cmd) {
  74         case SPECTRE_V2_CMD_NONE:
  75                 return SPECTRE_V2_USER_CMD_NONE;
  76         case SPECTRE_V2_CMD_FORCE:
  77 @@ -1010,7 +1019,7 @@ static inline bool spectre_v2_in_ibrs_mo
  78  }
  79
  80  static void __init
  81 -spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
  82 +spectre_v2_user_select_mitigation(void)
  83  {
  84         enum spectre_v2_user_mitigation mode = SPECTRE_V2_USER_NONE;
  85         bool smt_possible = IS_ENABLED(CONFIG_SMP);
  86 @@ -1023,7 +1032,7 @@ spectre_v2_user_select_mitigation(enum s
  87             cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
  88                 smt_possible = false;
  89
  90 -       cmd = spectre_v2_parse_user_cmdline(v2_cmd);
  91 +       cmd = spectre_v2_parse_user_cmdline();
  92         switch (cmd) {
  93         case SPECTRE_V2_USER_CMD_NONE:
  94                 goto set_mode;
  95 @@ -1347,7 +1356,7 @@ static void __init spectre_v2_select_mit
  96         }
  97
  98         /* Set up IBPB and STIBP depending on the general spectre V2 command */
  99 -       spectre_v2_user_select_mitigation(cmd);
 100 +       spectre_v2_cmd = cmd;
 101  }
 102
 103  static void update_stibp_msr(void * __unused)