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Date: Thu, 16 Sep 2021 11:35:42 -0700
From: Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>
To: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
x86@...nel.org, Paolo Bonzini <pbonzini@...hat.com>,
Juergen Gross <jgross@...e.com>, Deep Shah <sdeep@...are.com>,
VMware Inc <pv-drivers@...are.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>
Cc: Peter H Anvin <hpa@...or.com>, Dave Hansen <dave.hansen@...el.com>,
Tony Luck <tony.luck@...el.com>,
Dan Williams <dan.j.williams@...el.com>,
Andi Kleen <ak@...ux.intel.com>,
Kirill Shutemov <kirill.shutemov@...ux.intel.com>,
Sean Christopherson <seanjc@...gle.com>,
Kuppuswamy Sathyanarayanan <knsathya@...nel.org>,
linux-kernel@...r.kernel.org
Subject: [PATCH v7 04/12] x86/cpufeatures: Add TDX Guest CPU feature
Add CPU feature detection for Trusted Domain Extensions support. TDX
feature adds capabilities to keep guest register state and memory
isolated from hypervisor.
For TDX guest platforms, executing CPUID(eax=0x21, ecx=0) will return
following values in EAX, EBX, ECX and EDX.
EAX: Maximum sub-leaf number: 0
EBX/EDX/ECX: Vendor string:
EBX = "Inte"
EDX = "lTDX"
ECX = " "
So when above condition is true, set X86_FEATURE_TDX_GUEST feature cap
bit.
Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@...ux.intel.com>
---
arch/x86/include/asm/cpufeatures.h | 1 +
arch/x86/include/asm/tdx.h | 20 ++++++++++++++++++++
arch/x86/kernel/Makefile | 2 ++
arch/x86/kernel/head64.c | 3 +++
arch/x86/kernel/tdx.c | 29 +++++++++++++++++++++++++++++
5 files changed, 55 insertions(+)
create mode 100644 arch/x86/include/asm/tdx.h
create mode 100644 arch/x86/kernel/tdx.c
diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index d0ce5cfd3ac1..84997abeb401 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -238,6 +238,7 @@
#define X86_FEATURE_VMW_VMMCALL ( 8*32+19) /* "" VMware prefers VMMCALL hypercall instruction */
#define X86_FEATURE_PVUNLOCK ( 8*32+20) /* "" PV unlock function */
#define X86_FEATURE_VCPUPREEMPT ( 8*32+21) /* "" PV vcpu_is_preempted function */
+#define X86_FEATURE_TDX_GUEST ( 8*32+22) /* Trusted Domain Extensions Guest */
/* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
#define X86_FEATURE_FSGSBASE ( 9*32+ 0) /* RDFSBASE, WRFSBASE, RDGSBASE, WRGSBASE instructions*/
diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h
new file mode 100644
index 000000000000..c738bde944d1
--- /dev/null
+++ b/arch/x86/include/asm/tdx.h
@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2020 Intel Corporation */
+#ifndef _ASM_X86_TDX_H
+#define _ASM_X86_TDX_H
+
+#include <linux/cpufeature.h>
+
+#define TDX_CPUID_LEAF_ID 0x21
+
+#ifdef CONFIG_INTEL_TDX_GUEST
+
+void __init tdx_early_init(void);
+
+#else
+
+static inline void tdx_early_init(void) { };
+
+#endif /* CONFIG_INTEL_TDX_GUEST */
+
+#endif /* _ASM_X86_TDX_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index f91403a78594..159fccfece65 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -29,6 +29,7 @@ KASAN_SANITIZE_dumpstack_$(BITS).o := n
KASAN_SANITIZE_stacktrace.o := n
KASAN_SANITIZE_paravirt.o := n
KASAN_SANITIZE_sev.o := n
+KASAN_SANITIZE_tdx.o := n
# With some compiler versions the generated code results in boot hangs, caused
# by several compilation units. To be safe, disable all instrumentation.
@@ -127,6 +128,7 @@ obj-$(CONFIG_PARAVIRT_CLOCK) += pvclock.o
obj-$(CONFIG_X86_PMEM_LEGACY_DEVICE) += pmem.o
obj-$(CONFIG_JAILHOUSE_GUEST) += jailhouse.o
+obj-$(CONFIG_INTEL_TDX_GUEST) += tdx.o
obj-$(CONFIG_EISA) += eisa.o
obj-$(CONFIG_PCSPKR_PLATFORM) += pcspeaker.o
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index f98c76a1d16c..10c2568d7c42 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -40,6 +40,7 @@
#include <asm/extable.h>
#include <asm/trapnr.h>
#include <asm/sev.h>
+#include <asm/tdx.h>
/*
* Manage page tables very early on.
@@ -495,6 +496,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
copy_bootdata(__va(real_mode_data));
+ tdx_early_init();
+
/*
* Load microcode early on BSP.
*/
diff --git a/arch/x86/kernel/tdx.c b/arch/x86/kernel/tdx.c
new file mode 100644
index 000000000000..39dd1515b131
--- /dev/null
+++ b/arch/x86/kernel/tdx.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2020 Intel Corporation */
+
+#undef pr_fmt
+#define pr_fmt(fmt) "x86/tdx: " fmt
+
+#include <asm/tdx.h>
+
+static inline bool cpuid_has_tdx_guest(void)
+{
+ u32 eax, sig[3];
+
+ if (cpuid_eax(0) < TDX_CPUID_LEAF_ID)
+ return false;
+
+ cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]);
+
+ return !memcmp("IntelTDX ", sig, 12);
+}
+
+void __init tdx_early_init(void)
+{
+ if (!cpuid_has_tdx_guest())
+ return;
+
+ setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
+
+ pr_info("Guest initialized\n");
+}
--
2.25.1
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