Messages in this thread Patch in this message | | | From | Kuppuswamy Sathyanarayanan <> | Subject | [PATCH v10 03/11] x86/cpufeatures: Add TDX Guest CPU feature | Date | Fri, 8 Oct 2021 22:37:39 -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 v9: * Added inline definition of is_tdx_guest() for !CONFIG_INTEL_TDX_GUEST case.
Changes since v8: * Changed is_tdx_guest variable to is_tdx_guest() function. * Added -fno-stack-protector and -pg for tdx.c * Fixed tdx_early_init() related comments in x86_64_start_kernel() as per review suggestion.
Changes since v7: * Add comments for the order of tdx_early_init() call. * Similar to AMD (sme_me_mask) added a global variable is_tdx_guest for Intel TDX related checks. * Changed pr_fmt from "x86/tdx: " to "tdx:"
arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/include/asm/tdx.h | 22 +++++++++++++++++ arch/x86/kernel/Makefile | 4 ++++ arch/x86/kernel/head64.c | 9 +++++++ arch/x86/kernel/tdx.c | 38 ++++++++++++++++++++++++++++++ 5 files changed, 74 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..96ffce7bc530 --- /dev/null +++ b/arch/x86/include/asm/tdx.h @@ -0,0 +1,22 @@ +/* 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 + +bool is_tdx_guest(void); +void __init tdx_early_init(void); + +#else + +static inline bool is_tdx_guest(void) { return false; } +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 2ff3e600f426..8c9a9214dd34 100644 --- a/arch/x86/kernel/Makefile +++ b/arch/x86/kernel/Makefile @@ -22,6 +22,7 @@ CFLAGS_REMOVE_early_printk.o = -pg CFLAGS_REMOVE_head64.o = -pg CFLAGS_REMOVE_sev.o = -pg CFLAGS_REMOVE_cc_platform.o = -pg +CFLAGS_REMOVE_tdx.o = -pg endif KASAN_SANITIZE_head$(BITS).o := n @@ -31,6 +32,7 @@ KASAN_SANITIZE_stacktrace.o := n KASAN_SANITIZE_paravirt.o := n KASAN_SANITIZE_sev.o := n KASAN_SANITIZE_cc_platform.o := n +KASAN_SANITIZE_tdx.o := n # With some compiler versions the generated code results in boot hangs, caused # by several compilation units. To be safe, disable all instrumentation. @@ -50,6 +52,7 @@ KCOV_INSTRUMENT := n CFLAGS_head$(BITS).o += -fno-stack-protector CFLAGS_cc_platform.o += -fno-stack-protector +CFLAGS_tdx.o += -fno-stack-protector CFLAGS_irq.o := -I $(srctree)/$(src)/../include/asm/trace @@ -130,6 +133,7 @@ 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..a5ee90df2aba 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. @@ -500,6 +501,14 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data) copy_bootdata(__va(real_mode_data)); + /* + * A future dependency on cmdline parameters is expected (for + * adding debug options). So the order of calling it should be + * after copy_bootdata() (in which command line parameter is + * initialized). + */ + 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..88bf12788684 --- /dev/null +++ b/arch/x86/kernel/tdx.c @@ -0,0 +1,38 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2020 Intel Corporation */ + +#undef pr_fmt +#define pr_fmt(fmt) "tdx: " fmt + +#include <asm/tdx.h> + +bool is_tdx_guest(void) +{ + static int tdx_guest = -1; + u32 eax, sig[3]; + + if (tdx_guest >= 0) + goto done; + + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) { + tdx_guest = 0; + goto done; + } + + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]); + + tdx_guest = !memcmp("IntelTDX ", sig, 12); + +done: + return !!tdx_guest; +} + +void __init tdx_early_init(void) +{ + if (!is_tdx_guest()) + return; + + setup_force_cpu_cap(X86_FEATURE_TDX_GUEST); + + pr_info("Guest initialized\n"); +} -- 2.25.1
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