Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Vladis Dronov
authored
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