Messages in this thread Patch in this message | | | From | "Kirill A. Shutemov" <> | Subject | [PATCH 01/26] x86/tdx: Detect running as a TDX guest in early boot | Date | Tue, 14 Dec 2021 18:02:39 +0300 |
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From: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@linux.intel.com>
cc_platform_has() API is used in the kernel to enable confidential computing features. Since TDX guest is a confidential computing platform, it also needs to use this API.
In preparation of extending cc_platform_has() API to support TDX guest, use CPUID instruction to detect for TDX guests support in the early boot code (via tdx_early_init()). Since copy_bootdata() is the first user of cc_platform_has() API, detect the TDX guest status before it.
Since cc_plaform_has() API will be used frequently across the boot code, instead of repeatedly detecting the TDX guest status using the CPUID instruction, detect once and cache the result. Add a function (is_tdx_guest()) to read the cached TDX guest status in CC APIs.
Define a synthetic feature flag (X86_FEATURE_TDX_GUEST) and set this bit in a valid TDX guest platform. This feature bit will be used to do TDX-specific handling in some areas of the ARCH code where a function call to check for TDX guest status is not cost-effective (for example, TDX hypercall support).
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> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> --- arch/x86/Kconfig | 13 +++++++++ arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/disabled-features.h | 8 +++++- arch/x86/include/asm/tdx.h | 22 +++++++++++++++ arch/x86/kernel/Makefile | 1 + arch/x86/kernel/head64.c | 4 +++ arch/x86/kernel/tdx.c | 34 ++++++++++++++++++++++++ 7 files changed, 82 insertions(+), 1 deletion(-) create mode 100644 arch/x86/include/asm/tdx.h create mode 100644 arch/x86/kernel/tdx.c
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 793e9b42ace0..a61ac6f8821a 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -872,6 +872,19 @@ config ACRN_GUEST IOT with small footprint and real-time features. More details can be found in https://projectacrn.org/. +# TDX guest uses X2APIC for interrupt management. +config INTEL_TDX_GUEST + bool "Intel TDX (Trust Domain Extensions) - Guest Support" + depends on X86_64 && CPU_SUP_INTEL + depends on X86_X2APIC + help + Support running as a guest under Intel TDX. Without this support, + the guest kernel can not boot or run under TDX. + TDX includes memory encryption and integrity capabilities + which protect the confidentiality and integrity of guest + memory contents and CPU state. TDX guests are protected from + potential attacks from the VMM. + endif #HYPERVISOR_GUEST source "arch/x86/Kconfig.cpu" diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h index d5b5f2ab87a0..fb178544fd21 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) /* Intel Trust 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/disabled-features.h b/arch/x86/include/asm/disabled-features.h index 8f28fafa98b3..f556086e6093 100644 --- a/arch/x86/include/asm/disabled-features.h +++ b/arch/x86/include/asm/disabled-features.h @@ -65,6 +65,12 @@ # define DISABLE_SGX (1 << (X86_FEATURE_SGX & 31)) #endif +#ifdef CONFIG_INTEL_TDX_GUEST +# define DISABLE_TDX_GUEST 0 +#else +# define DISABLE_TDX_GUEST (1 << (X86_FEATURE_TDX_GUEST & 31)) +#endif + /* * Make sure to add features to the correct mask */ @@ -76,7 +82,7 @@ #define DISABLED_MASK5 0 #define DISABLED_MASK6 0 #define DISABLED_MASK7 (DISABLE_PTI) -#define DISABLED_MASK8 0 +#define DISABLED_MASK8 (DISABLE_TDX_GUEST) #define DISABLED_MASK9 (DISABLE_SMAP|DISABLE_SGX) #define DISABLED_MASK10 0 #define DISABLED_MASK11 0 diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h new file mode 100644 index 000000000000..686168941f92 --- /dev/null +++ b/arch/x86/include/asm/tdx.h @@ -0,0 +1,22 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2021-2022 Intel Corporation */ +#ifndef _ASM_X86_TDX_H +#define _ASM_X86_TDX_H + +#include <linux/init.h> + +#define TDX_CPUID_LEAF_ID 0x21 + +#ifdef CONFIG_INTEL_TDX_GUEST + +void __init tdx_early_init(void); +bool is_tdx_guest(void); + +#else + +static inline void tdx_early_init(void) { }; +static inline bool is_tdx_guest(void) { return false; } + +#endif /* CONFIG_INTEL_TDX_GUEST */ + +#endif /* _ASM_X86_TDX_H */ diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile index 2ff3e600f426..64f9babcfd95 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -130,6 +130,7 @@ 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 fc5371a7e9d1..66deb2611dc5 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. @@ -498,6 +499,9 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) idt_setup_early_handler(); + /* Needed before cc_platform_has() can be used for TDX: */ + tdx_early_init(); + 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..d32d9d9946d8 --- /dev/null +++ b/arch/x86/kernel/tdx.c @@ -0,0 +1,34 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2021-2022 Intel Corporation */ + +#undef pr_fmt +#define pr_fmt(fmt) "tdx: " fmt + +#include <linux/cpufeature.h> +#include <asm/tdx.h> + +static bool tdx_guest_detected __ro_after_init; + +bool is_tdx_guest(void) +{ + return tdx_guest_detected; +} + +void __init tdx_early_init(void) +{ + u32 eax, sig[3]; + + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) + return; + + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]); + + if (memcmp("IntelTDX ", sig, 12)) + return; + + tdx_guest_detected = true; + + setup_force_cpu_cap(X86_FEATURE_TDX_GUEST); + + pr_info("Guest detected\n"); +} -- 2.32.0
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