Messages in this thread Patch in this message | | | From | Kuppuswamy Sathyanarayanan <> | Subject | [PATCH v1 03/11] x86/cpufeatures: Add TDX Guest CPU feature | Date | Tue, 1 Jun 2021 19:18:27 -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(0x21, 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> Reviewed-by: Andi Kleen <ak@linux.intel.com> Reviewed-by: Tony Luck <tony.luck@intel.com> --- 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 | 30 ++++++++++++++++++++++++++++++ 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 ac37830ae941..dddc3a27cc8a 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..679500e807f3 --- /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 + +#define TDX_CPUID_LEAF_ID 0x21 + +#ifdef CONFIG_INTEL_TDX_GUEST + +#include <asm/cpufeature.h> + +void __init tdx_early_init(void); + +#else // !CONFIG_INTEL_TDX_GUEST + +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 0f66682ac02a..af09ce93a641 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -126,6 +126,7 @@ 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..5b14b72e41c5 --- /dev/null +++ b/arch/x86/kernel/tdx.c @@ -0,0 +1,30 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2020 Intel Corporation */ + +#include <asm/tdx.h> + +static inline bool cpuid_has_tdx_guest(void) +{ + u32 eax, signature[3]; + + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) + return false; + + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &signature[0], + &signature[1], &signature[2]); + + if (memcmp("IntelTDX ", signature, 12)) + return false; + + return true; +} + +void __init tdx_early_init(void) +{ + if (!cpuid_has_tdx_guest()) + return; + + setup_force_cpu_cap(X86_FEATURE_TDX_GUEST); + + pr_info("TDX guest is initialized\n"); +} -- 2.25.1
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