linux-kernel - [PATCH v17 12/23] x86/sgx: Add definitions for SGX's CPUID leaf and variable sub-leafs

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Date:   Fri, 16 Nov 2018 03:01:19 +0200
From:   Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To:     x86@...nel.org, platform-driver-x86@...r.kernel.org,
        linux-sgx@...r.kernel.org
Cc:     dave.hansen@...el.com, sean.j.christopherson@...el.com,
        nhorman@...hat.com, npmccallum@...hat.com, serge.ayoun@...el.com,
        shay.katz-zamir@...el.com, haitao.huang@...ux.intel.com,
        andriy.shevchenko@...ux.intel.com, tglx@...utronix.de,
        kai.svahn@...el.com, mark.shanahan@...el.com, luto@...capital.net,
        Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND
        64-BIT))
Subject: [PATCH v17 12/23] x86/sgx: Add definitions for SGX's CPUID leaf and variable sub-leafs

SGX defines its own CPUID leaf, 0x12, along with a variable number of
sub-leafs.  Sub-leafs 0 and 1 are always available if SGX is supported
and enumerate various SGX features, e.g. instruction sets and enclave
capabilities.  Sub-leafs 2+ are variable, both in their existence and
in what they enumerate.  Bits 3:0 of EAX report the sub-leaf type,
with the remaining bits in EAX, EBX, ECX and EDX being type-specific.
Currently, the only known sub-leaf type enumerates an EPC section.  An
EPC section is simply a range of EPC memory available to software.
The "list" of varaible SGX sub-leafs is NULL-terminated, i.e. software
is expected to query CPUID until an invalid sub-leaf is encountered.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
Co-developed-by: Sean Christopherson <sean.j.christopherson@...el.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/sgx_arch.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/x86/include/asm/sgx_arch.h b/arch/x86/include/asm/sgx_arch.h
index d4c57154e6e6..188243e3eee1 100644
--- a/arch/x86/include/asm/sgx_arch.h
+++ b/arch/x86/include/asm/sgx_arch.h
@@ -11,6 +11,21 @@
 #include <linux/types.h>
 #include <uapi/asm/sgx_errno.h>
 
+#define SGX_CPUID				0x12
+#define SGX_CPUID_FIRST_VARIABLE_SUB_LEAF	2
+
+/**
+ * enum sgx_sub_leaf_types - SGX CPUID variable sub-leaf types
+ * %SGX_CPUID_SUB_LEAF_INVALID:		Indicates this sub-leaf is invalid.
+ * %SGX_CPUID_SUB_LEAF_EPC_SECTION:	Sub-leaf enumerates an EPC section.
+ * %SGX_CPUID_SUB_LEAF_TYPE_MASK:	Mask for bits containing the type.
+ */
+enum sgx_sub_leaf_types {
+	SGX_CPUID_SUB_LEAF_INVALID	= 0x0,
+	SGX_CPUID_SUB_LEAF_EPC_SECTION	= 0x1,
+	SGX_CPUID_SUB_LEAF_TYPE_MASK	= GENMASK(3, 0),
+};
+
 /**
  * enum sgx_encls_leaves - ENCLS leaf functions
  * %SGX_ECREATE:	Create an enclave.
-- 
2.19.1