diff options
| author | Pawan Gupta <pawan.kumar.gupta@linux.intel.com> | 2024-12-02 12:07:08 -0800 |
|---|---|---|
| committer | Dave Hansen <dave.hansen@linux.intel.com> | 2025-05-09 13:22:05 -0700 |
| commit | facd226f7e0c8ca936ac114aba43cb3e8b94e41e (patch) | |
| tree | b2dd9cb6ecfa2b5c0db188ce295ede9e2fe96b69 | |
| parent | 2665281a07e19550944e8354a2024635a7b2714a (diff) | |
x86/its: Add support for RSB stuffing mitigation
When retpoline mitigation is enabled for spectre-v2, enabling
call-depth-tracking and RSB stuffing also mitigates ITS. Add cmdline option
indirect_target_selection=stuff to allow enabling RSB stuffing mitigation.
When retpoline mitigation is not enabled, =stuff option is ignored, and
default mitigation for ITS is deployed.
Signed-off-by: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Josh Poimboeuf <jpoimboe@kernel.org>
Reviewed-by: Alexandre Chartre <alexandre.chartre@oracle.com>
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 3 | ||||
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 19 |
2 files changed, 22 insertions, 0 deletions
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index e70d15095f28..8f75ec177399 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2212,6 +2212,9 @@ mitigation. vmexit: Only deploy mitigation if CPU is affected by guest/host isolation part of ITS. + stuff: Deploy RSB-fill mitigation when retpoline is + also deployed. Otherwise, deploy the default + mitigation. For details see: Documentation/admin-guide/hw-vuln/indirect-target-selection.rst diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index e919d645d830..c6dcc03a43da 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1204,6 +1204,7 @@ enum its_mitigation_cmd { ITS_CMD_OFF, ITS_CMD_ON, ITS_CMD_VMEXIT, + ITS_CMD_RSB_STUFF, }; enum its_mitigation { @@ -1244,6 +1245,8 @@ static int __init its_parse_cmdline(char *str) setup_force_cpu_bug(X86_BUG_ITS); } else if (!strcmp(str, "vmexit")) { its_cmd = ITS_CMD_VMEXIT; + } else if (!strcmp(str, "stuff")) { + its_cmd = ITS_CMD_RSB_STUFF; } else { pr_err("Ignoring unknown indirect_target_selection option (%s).", str); } @@ -1295,6 +1298,12 @@ static void __init its_select_mitigation(void) goto out; } + if (cmd == ITS_CMD_RSB_STUFF && + (!boot_cpu_has(X86_FEATURE_RETPOLINE) || !IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING))) { + pr_err("RSB stuff mitigation not supported, using default\n"); + cmd = ITS_CMD_ON; + } + switch (cmd) { case ITS_CMD_OFF: its_mitigation = ITS_MITIGATION_OFF; @@ -1312,6 +1321,16 @@ static void __init its_select_mitigation(void) setup_force_cpu_cap(X86_FEATURE_RETHUNK); set_return_thunk(its_return_thunk); break; + case ITS_CMD_RSB_STUFF: + its_mitigation = ITS_MITIGATION_RETPOLINE_STUFF; + setup_force_cpu_cap(X86_FEATURE_RETHUNK); + setup_force_cpu_cap(X86_FEATURE_CALL_DEPTH); + set_return_thunk(call_depth_return_thunk); + if (retbleed_mitigation == RETBLEED_MITIGATION_NONE) { + retbleed_mitigation = RETBLEED_MITIGATION_STUFF; + pr_info("Retbleed mitigation updated to stuffing\n"); + } + break; } out: pr_info("%s\n", its_strings[its_mitigation]); |