Messages in this thread Patch in this message | | | From | Martin Fernandez <> | Subject | [PATCH v2] x86/cpuinfo: Clear X86_FEATURE_TME if TME/MKTME is disabled by BIOS | Date | Mon, 4 Jul 2022 11:22:51 -0300 |
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Right now the only way to check this is by greping the kernel logs, which is inconvenient. This is currently checked for fwupd for example.
I understand that cpuinfo is supposed to report every feature in the cpu but since AMD is doing the same (and it also broke backwards compatibility [1]) for sme/sev I think it's good to have this for Intel too.
Another option to prevent greping the logs would be a file in sysfs. I'm open to suggestions to where to place this infomartion. I saw a proposal about a firmware security filesystem [2]; that would fit perfectly.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/patch/?id=08f253ec3767bcfafc5d32617a92cee57c63968e
[2] https://lore.kernel.org/all/20220622215648.96723-3-nayna@linux.ibm.com/
Changelog since v1
Clear the flag not only for BSP but for every cpu in the system.
Signed-off-by: Martin Fernandez <martin.fernandez@eclypsium.com> --- arch/x86/kernel/cpu/intel.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/arch/x86/kernel/cpu/intel.c b/arch/x86/kernel/cpu/intel.c index fd5dead8371c..17f23e23f911 100644 --- a/arch/x86/kernel/cpu/intel.c +++ b/arch/x86/kernel/cpu/intel.c @@ -570,6 +570,7 @@ static void detect_tme(struct cpuinfo_x86 *c)
if (!TME_ACTIVATE_LOCKED(tme_activate) || !TME_ACTIVATE_ENABLED(tme_activate)) { pr_info_once("x86/tme: not enabled by BIOS\n"); + clear_cpu_cap(c, X86_FEATURE_TME); mktme_status = MKTME_DISABLED; return; } -- 2.30.2
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