diff options
| author | Vladis Dronov <vdronov@redhat.com> | 2025-03-09 18:22:16 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2025-03-10 12:29:18 +0100 |
| commit | 65be5c95d08eedda570a6c888a12384c77fe7614 (patch) | |
| tree | fd34ae9a120e078a38e3d42642b92a860865ca0f | |
| parent | 80e54e84911a923c40d7bee33a34c1b4be148d7a (diff) | |
x86/sgx: Warn explicitly if X86_FEATURE_SGX_LC is not enabled
The kernel requires X86_FEATURE_SGX_LC to be able to create SGX enclaves,
not just X86_FEATURE_SGX.
There is quite a number of hardware which has X86_FEATURE_SGX but not
X86_FEATURE_SGX_LC. A kernel running on such hardware does not create
the /dev/sgx_enclave file and does so silently.
Explicitly warn if X86_FEATURE_SGX_LC is not enabled to properly notify
users that the kernel disabled the SGX driver.
The X86_FEATURE_SGX_LC, a.k.a. SGX Launch Control, is a CPU feature
that enables LE (Launch Enclave) hash MSRs to be writable (with
additional opt-in required in the 'feature control' MSR) when running
enclaves, i.e. using a custom root key rather than the Intel proprietary
key for enclave signing.
I've hit this issue myself and have spent some time researching where
my /dev/sgx_enclave file went on SGX-enabled hardware.
Related links:
https://github.com/intel/linux-sgx/issues/837
https://patchwork.kernel.org/project/platform-driver-x86/patch/20180827185507.17087-3-jarkko.sakkinen@linux.intel.com/
[ mingo: Made the error message a bit more verbose, and added other cases
where the kernel fails to create the /dev/sgx_enclave device node. ]
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Kai Huang <kai.huang@intel.com>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Sean Christopherson <sean.j.christopherson@intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250309172215.21777-2-vdronov@redhat.com
| -rw-r--r-- | arch/x86/kernel/cpu/sgx/driver.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/arch/x86/kernel/cpu/sgx/driver.c b/arch/x86/kernel/cpu/sgx/driver.c index 22b65a5f5ec6..7f8d1e11dbee 100644 --- a/arch/x86/kernel/cpu/sgx/driver.c +++ b/arch/x86/kernel/cpu/sgx/driver.c @@ -150,13 +150,15 @@ int __init sgx_drv_init(void) u64 xfrm_mask; int ret; - if (!cpu_feature_enabled(X86_FEATURE_SGX_LC)) + if (!cpu_feature_enabled(X86_FEATURE_SGX_LC)) { + pr_info("SGX disabled: SGX launch control CPU feature is not available, /dev/sgx_enclave disabled.\n"); return -ENODEV; + } cpuid_count(SGX_CPUID, 0, &eax, &ebx, &ecx, &edx); if (!(eax & 1)) { - pr_err("SGX disabled: SGX1 instruction support not available.\n"); + pr_info("SGX disabled: SGX1 instruction support not available, /dev/sgx_enclave disabled.\n"); return -ENODEV; } @@ -173,8 +175,10 @@ int __init sgx_drv_init(void) } ret = misc_register(&sgx_dev_enclave); - if (ret) + if (ret) { + pr_info("SGX disabled: Unable to register the /dev/sgx_enclave driver (%d).\n", ret); return ret; + } return 0; } |