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    Subject[PATCH v13 06/13] x86/sgx: Detect Intel SGX
    Date
    From: Sean Christopherson <sean.j.christopherson@intel.com>

    Intel(R) SGX is a set of CPU instructions that can be used by applications
    to set aside private regions of code and data. The code outside the enclave
    is disallowed to access the memory inside the enclave by the CPU access
    control.

    Add a check for SGX to arch/x86 and a new config option, INTEL_SGX_CORE.
    Expose a boolean variable 'sgx_enabled' to query whether or not the SGX
    support is available.

    Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
    Co-developed-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    Co-developed-by: Suresh Siddha <suresh.b.siddha@intel.com>
    Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
    Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
    ---
    arch/x86/Kconfig | 19 +++++++++++++
    arch/x86/include/asm/sgx.h | 12 +++++++++
    arch/x86/include/asm/sgx_pr.h | 13 +++++++++
    arch/x86/kernel/cpu/Makefile | 1 +
    arch/x86/kernel/cpu/intel_sgx.c | 47 +++++++++++++++++++++++++++++++++
    5 files changed, 92 insertions(+)
    create mode 100644 arch/x86/include/asm/sgx.h
    create mode 100644 arch/x86/include/asm/sgx_pr.h
    create mode 100644 arch/x86/kernel/cpu/intel_sgx.c

    diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
    index b0312f8947ce..3c7571422a07 100644
    --- a/arch/x86/Kconfig
    +++ b/arch/x86/Kconfig
    @@ -1911,6 +1911,25 @@ config X86_INTEL_MEMORY_PROTECTION_KEYS

    If unsure, say y.

    +config INTEL_SGX_CORE
    + prompt "Intel SGX core functionality"
    + def_bool n
    + 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.
    +
    + 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..2130e639ab49
    --- /dev/null
    +++ b/arch/x86/include/asm/sgx.h
    @@ -0,0 +1,12 @@
    +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
    +// Copyright(c) 2016-18 Intel Corporation.
    +
    +#ifndef _ASM_X86_SGX_H
    +#define _ASM_X86_SGX_H
    +
    +#include <linux/types.h>
    +
    +extern bool sgx_enabled;
    +extern bool sgx_lc_enabled;
    +
    +#endif /* _ASM_X86_SGX_H */
    diff --git a/arch/x86/include/asm/sgx_pr.h b/arch/x86/include/asm/sgx_pr.h
    new file mode 100644
    index 000000000000..c68578127620
    --- /dev/null
    +++ b/arch/x86/include/asm/sgx_pr.h
    @@ -0,0 +1,13 @@
    +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
    +// Copyright(c) 2016-17 Intel Corporation.
    +
    +#ifndef _ASM_X86_SGX_PR_H
    +#define _ASM_X86_SGX_PR_H
    +
    +#include <linux/printk.h>
    +#include <linux/ratelimit.h>
    +
    +#undef pr_fmt
    +#define pr_fmt(fmt) "sgx: " fmt
    +
    +#endif /* _ASM_X86_SGX_PR_H */
    diff --git a/arch/x86/kernel/cpu/Makefile b/arch/x86/kernel/cpu/Makefile
    index 347137e80bf5..71876f2b35fc 100644
    --- a/arch/x86/kernel/cpu/Makefile
    +++ b/arch/x86/kernel/cpu/Makefile
    @@ -38,6 +38,7 @@ obj-$(CONFIG_CPU_SUP_UMC_32) += umc.o
    obj-$(CONFIG_INTEL_RDT) += intel_rdt.o intel_rdt_rdtgroup.o intel_rdt_monitor.o
    obj-$(CONFIG_INTEL_RDT) += intel_rdt_ctrlmondata.o intel_rdt_pseudo_lock.o
    CFLAGS_intel_rdt_pseudo_lock.o = -I$(src)
    +obj-$(CONFIG_INTEL_SGX_CORE) += intel_sgx.o

    obj-$(CONFIG_X86_MCE) += mcheck/
    obj-$(CONFIG_MTRR) += mtrr/
    diff --git a/arch/x86/kernel/cpu/intel_sgx.c b/arch/x86/kernel/cpu/intel_sgx.c
    new file mode 100644
    index 000000000000..17b46bec9c54
    --- /dev/null
    +++ b/arch/x86/kernel/cpu/intel_sgx.c
    @@ -0,0 +1,47 @@
    +// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
    +// Copyright(c) 2016-17 Intel Corporation.
    +
    +#include <asm/sgx.h>
    +#include <asm/sgx_pr.h>
    +#include <linux/freezer.h>
    +#include <linux/highmem.h>
    +#include <linux/kthread.h>
    +#include <linux/ratelimit.h>
    +#include <linux/sched/signal.h>
    +#include <linux/slab.h>
    +
    +bool sgx_enabled __ro_after_init;
    +EXPORT_SYMBOL_GPL(sgx_enabled);
    +bool sgx_lc_enabled __ro_after_init;
    +EXPORT_SYMBOL_GPL(sgx_lc_enabled);
    +
    +static __init int sgx_init(void)
    +{
    + unsigned long fc;
    +
    + 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)) {
    + pr_info("IA32_FEATURE_CONTROL MSR is not locked\n");
    + return false;
    + }
    +
    + if (!(fc & FEATURE_CONTROL_SGX_ENABLE)) {
    + pr_info("disabled by the firmware\n");
    + return false;
    + }
    +
    + if (!(fc & FEATURE_CONTROL_SGX_LE_WR))
    + pr_info("IA32_SGXLEPUBKEYHASHn MSRs are not writable\n");
    +
    + sgx_enabled = true;
    + sgx_lc_enabled = !!(fc & FEATURE_CONTROL_SGX_LE_WR);
    + return 0;
    +}
    +
    +arch_initcall(sgx_init);
    --
    2.17.1
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