This reverts commit 7adb96687ce8819de5c7bb172c4eeb6e45736e06.

commit 7adb96687ce8 ("x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2") depends on commit 72c70f480a70 ("x86/bugs: Add a separate config for Spectre V2"), which introduced MITIGATION_SPECTRE_V2.

commit 72c70f480a70 ("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 --- PS: This patch is only for stable (6.6 and older). --- Documentation/admin-guide/kernel-parameters.txt | 2 -- arch/x86/kernel/cpu/bugs.c | 10 +++------- 2 files changed, 3 insertions(+), 9 deletions(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 315a817e33804..f95734ceb82b8 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -5978,8 +5978,6 @@

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. diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index e9c4bcb38f458..07b45bbf6348d 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1442,13 +1442,9 @@ static __ro_after_init enum spectre_v2_mitigation_cmd spectre_v2_cmd; static enum spectre_v2_user_cmd __init 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; @@ -1461,7 +1457,7 @@ spectre_v2_parse_user_cmdline(void) ret = cmdline_find_option(boot_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)) { @@ -1471,8 +1467,8 @@ 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_ibrs_mode(enum spectre_v2_mitigation mode)

--- base-commit: 6282921b6825fef6a1243e1c80063421d41e2576 change-id: 20250620-stable_revert_66-092ba4e66bec prerequisite-change-id: 20250620-stable_revert-1809dd16f554:v1

Best regards, -- Breno Leitao leitao@debian.org