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| author | Breno Leitao <leitao@debian.org> | 2024-10-31 04:06:17 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-29 11:02:33 +0200 |
| commit | e7e30a4a37d1e5fd0bae01a51ef738c17606f9f8 (patch) | |
| tree | 1481671b62544e80fc6de8baf5ab401ad2eec420 | |
| parent | 0d232fa3b07690035da54836346898eab441a4ad (diff) | |
x86/bugs: Make spectre user default depend on MITIGATION_SPECTRE_V2
[ Upstream commit 98fdaeb296f51ef08e727a7cc72e5b5c864c4f4d ]
Change the default value of spectre v2 in user mode to respect the
CONFIG_MITIGATION_SPECTRE_V2 config option.
Currently, user mode spectre v2 is set to auto
(SPECTRE_V2_USER_CMD_AUTO) by default, even if
CONFIG_MITIGATION_SPECTRE_V2 is disabled.
Set the spectre_v2 value to auto (SPECTRE_V2_USER_CMD_AUTO) if the
Spectre v2 config (CONFIG_MITIGATION_SPECTRE_V2) is enabled, otherwise
set the value to none (SPECTRE_V2_USER_CMD_NONE).
Important to say the command line argument "spectre_v2_user" overwrites
the default value in both cases.
When CONFIG_MITIGATION_SPECTRE_V2 is not set, users have the flexibility
to opt-in for specific mitigations independently. In this scenario,
setting spectre_v2= will not enable spectre_v2_user=, and command line
options spectre_v2_user and spectre_v2 are independent when
CONFIG_MITIGATION_SPECTRE_V2=n.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Acked-by: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Kaplan <David.Kaplan@amd.com>
Link: https://lore.kernel.org/r/20241031-x86_bugs_last_v2-v2-2-b7ff1dab840e@debian.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 2 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 10 |
2 files changed, 9 insertions, 3 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index e691f75c97e7..b5cb36148554 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6261,6 +6261,8 @@ 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 c683abd640fd..0e9ab0b9a494 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1442,9 +1442,13 @@ 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; @@ -1457,7 +1461,7 @@ spectre_v2_parse_user_cmdline(void) ret = cmdline_find_option(boot_command_line, "spectre_v2_user", arg, sizeof(arg)); if (ret < 0) - return SPECTRE_V2_USER_CMD_AUTO; + return mode; for (i = 0; i < ARRAY_SIZE(v2_user_options); i++) { if (match_option(arg, ret, v2_user_options[i].option)) { @@ -1467,8 +1471,8 @@ spectre_v2_parse_user_cmdline(void) } } - pr_err("Unknown user space protection option (%s). Switching to AUTO select\n", arg); - return SPECTRE_V2_USER_CMD_AUTO; + pr_err("Unknown user space protection option (%s). Switching to default\n", arg); + return mode; } static inline bool spectre_v2_in_ibrs_mode(enum spectre_v2_mitigation mode) |