On Fri, Jun 08, 2018 at 10:36:14AM -0700, Dave Hansen wrote:
> > +config INTEL_SGX_CORE
> > + prompt "Intel SGX core functionality
> > + depends on X86_64 && CPU_SUP_INTEL
> > + help
> > + Intel Software Guard eXtensions (SGX) is a set of CPU instructions
> > + that allows ring 3 applications to create enclaves; private regions
> > + of memory that are protected, by hardware, from unauthorized access
> > + and/or modification.
>
> That semicolon needs to be a colon. The second half of that sentence is
> not a stand-alone statement.
>
> > + This option enables kernel recognition of SGX, high-level management
> > + of the Enclave Page Cache (EPC), tracking and writing of SGX Launch
> > + Enclave Hash MSRs, and allows for virtualization of SGX via KVM. By
> > + iteslf, this option does not provide SGX support to userspace.
> > +
> > + For details, see Documentation/x86/intel_sgx.rst
> > +
> > + If unsure, say N.
> > +
> > config EFI
> > bool "EFI runtime service support"
> > depends on ACPI
> > diff --git a/arch/x86/include/asm/sgx.h b/arch/x86/include/asm/sgx.h
> > new file mode 100644
> > index 000000000000..fa3e6e0eb8af
> > --- /dev/null
> > +++ b/arch/x86/include/asm/sgx.h
> > @@ -0,0 +1,25 @@
> > +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
> > +// Copyright(c) 2016-18 Intel Corporation.
> > +//
> > +// Authors:
> > +//
> > +// Jarkko Sakkinen <[email protected]>
> > +// Suresh Siddha <[email protected]>
> > +// Sean Christopherson <[email protected]>
> > +
> > +#ifndef _ASM_X86_SGX_H
> > +#define _ASM_X86_SGX_H
> > +
> > +#include <linux/types.h>
> > +
> > +#define SGX_CPUID 0x12
>
> Hey, I just saw 0x12 as a magic, hard-coded number earlier in these
> patches. It seems cruel to hard-code it, and then also have a #define
> that isn't used.
It i then is a regression in the series. I'll fix it.
> > +enum sgx_cpuid {
> > + SGX_CPUID_CAPABILITIES = 0,
> > + SGX_CPUID_ATTRIBUTES = 1,
> > + SGX_CPUID_EPC_BANKS = 2,
> > +};
>
> These are cpuid *leaves*, right? Please make this clear that these are
> hardware-defined values and not some kind of software construct.
>
> > +bool sgx_enabled __ro_after_init = false;
> > +EXPORT_SYMBOL(sgx_enabled);
> > +
> > +static __init bool sgx_is_enabled(void)
> > +{
> > + unsigned long fc;
> > +
> > + if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
> > + return false;
>
> Not necessary. CPUID does this part for you.
>
> > + if (!boot_cpu_has(X86_FEATURE_SGX))
> > + return false;
> > +
> > + if (!boot_cpu_has(X86_FEATURE_SGX1))
> > + return false;
> > +
> > + rdmsrl(MSR_IA32_FEATURE_CONTROL, fc);
> > + if (!(fc & FEATURE_CONTROL_LOCKED))
> > + return false;
> > +
> > + if (!(fc & FEATURE_CONTROL_SGX_ENABLE))
> > + return false;
>
> Comments, please. Why would this happen? What would it mean?
Thanks for the feedback! I'll refine the parts that you pointed out.
/Jarkko
