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| author | Mario Limonciello <mario.limonciello@amd.com> | 2022-02-16 04:44:46 +0100 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-02-16 19:45:53 +0100 |
| commit | 08f253ec3767bcfafc5d32617a92cee57c63968e (patch) | |
| tree | 7904449a2af5f99762707db4fa3a42c0ee2ac519 /arch/x86/kernel/process.c | |
| parent | x86/cpufeatures: Put the AMX macros in the word 18 block (diff) | |
| download | linux-08f253ec3767bcfafc5d32617a92cee57c63968e.tar.xz linux-08f253ec3767bcfafc5d32617a92cee57c63968e.zip | |
x86/cpu: Clear SME feature flag when not in use
Currently, the SME CPU feature flag is reflective of whether the CPU
supports the feature but not whether it has been activated by the
kernel.
Change this around to clear the SME feature flag if the kernel is not
using it so userspace can determine if it is available and in use
from /proc/cpuinfo.
As the feature flag is cleared on systems where SME isn't active, use
CPUID 0x8000001f to confirm SME availability before calling
native_wbinvd().
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Acked-by: Tom Lendacky <thomas.lendacky@amd.com>
Link: https://lore.kernel.org/r/20220216034446.2430634-1-mario.limonciello@amd.com
Diffstat (limited to 'arch/x86/kernel/process.c')
| -rw-r--r-- | arch/x86/kernel/process.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c index 81d8ef036637..e131d71b3cae 100644 --- a/arch/x86/kernel/process.c +++ b/arch/x86/kernel/process.c @@ -765,8 +765,11 @@ void stop_this_cpu(void *dummy) * without the encryption bit, they don't race each other when flushed * and potentially end up with the wrong entry being committed to * memory. + * + * Test the CPUID bit directly because the machine might've cleared + * X86_FEATURE_SME due to cmdline options. */ - if (boot_cpu_has(X86_FEATURE_SME)) + if (cpuid_eax(0x8000001f) & BIT(0)) native_wbinvd(); for (;;) { /* |