Messages in this thread | | | Subject | Re: [PATCH v1 03/11] x86/cpufeatures: Add TDX Guest CPU feature | From | "Kuppuswamy, Sathyanarayanan" <> | Date | Thu, 10 Jun 2021 07:28:20 -0700 |
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Hi,
On 6/10/21 5:28 AM, Borislav Petkov wrote: > On Tue, Jun 01, 2021 at 07:21:28PM -0700, Kuppuswamy Sathyanarayanan wrote: >> 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 > > I'm assuming that 0 is ECX?
Correct. I will clarify it in commit log.
> >> 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 > ^ > Fullstop.
Will fix it in next version.
> >> 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 */ > > What's the name of the feature bit? "TDX guest"? Why not only > X86_FEATURE_TDX and then you can have "tdx" in cpuinfo?
Make sense. I can change it to "TDX". I guess we will not a feature bit for "tdx host"
> >> >> /* 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> > > As before - put the include at the top.
I will change it.
> >> +void __init tdx_early_init(void); >> + >> +#else // !CONFIG_INTEL_TDX_GUEST > > No need for that // - comment
I will remove it in next version.
> >> 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]; > > Shorten that array name to "sig" so that you don't have to break the > cpuid_count() line below.
I will fix it in next version.
> >> + >> + 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; > > or simply: > > return !memcmp(...
Got it. I will change it in next version.
> >> +} >> + >> +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"); > > Use pr_fmt in this file: > > #undef pr_fmt > #define pr_fmt(fmt) "x86/tdx: " fmt > > and then do > > pr_info("Guest initialized\n");
Patch titled "x86/tdx: Add __tdx_module_call() and __tdx_hypercall() helper functions" add it. It makes sense to move it to this patch.
> > Thx. >
-- Sathyanarayanan Kuppuswamy Linux Kernel Developer
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