Messages in this thread Patch in this message | | | From | Kuppuswamy Sathyanarayanan <> | Subject | [PATCH v4 03/11] x86/cpufeatures: Add TDX Guest CPU feature | Date | Mon, 19 Jul 2021 17:40:49 -0700 |
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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@linux.intel.com> ---
Changes since v3: * Fixed order of string cpuid_count() call.
Changes since v2: * Fixed debug prints as per Borislav suggestion.
Changes since v1: * Fixed commit log issues reported by Borislav. * Moved header file include to the start of tdx.h. * Added pr_fmt for TDX. * Simplified cpuid_has_tdx_guest() implementation as per Borislav comments.
arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/tdx.h | 20 ++++++++++++++++++++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/head64.c | 3 +++ arch/x86/kernel/tdx.c | 29 +++++++++++++++++++++++++++++ 5 files changed, 54 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 3e625c61f008..b49110bd50d9 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -127,6 +127,7 @@ 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 de01903c3735..d1a4942ae160 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. @@ -491,6 +492,8 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) kasan_early_init(); + tdx_early_init(); + idt_setup_early_handler(); copy_bootdata(__va(real_mode_data)); 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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