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08 Dec 2022 22:53:05 -0800 From: Kai Huang To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: linux-mm@kvack.org, dave.hansen@intel.com, peterz@infradead.org, tglx@linutronix.de, seanjc@google.com, pbonzini@redhat.com, dan.j.williams@intel.com, rafael.j.wysocki@intel.com, kirill.shutemov@linux.intel.com, ying.huang@intel.com, reinette.chatre@intel.com, len.brown@intel.com, tony.luck@intel.com, ak@linux.intel.com, isaku.yamahata@intel.com, chao.gao@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, bagasdotme@gmail.com, sagis@google.com, imammedo@redhat.com, kai.huang@intel.com Subject: [PATCH v8 02/16] x86/virt/tdx: Detect TDX during kernel boot Date: Fri, 9 Dec 2022 19:52:23 +1300 Message-Id: <75317b5b6f29e77b98455b0401bd903964f50814.1670566861.git.kai.huang@intel.com> X-Mailer: git-send-email 2.38.1 In-Reply-To: References: MIME-Version: 1.0 X-Rspamd-Queue-Id: 956FB1C0002 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: skxtoynyo789owdokw66row4ianesko3 X-HE-Tag: 1670568791-939360 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Intel Trust Domain Extensions (TDX) protects guest VMs from malicious host and certain physical attacks. A CPU-attested software module called 'the TDX module' runs inside a new isolated memory range as a trusted hypervisor to manage and run protected VMs. Pre-TDX Intel hardware has support for a memory encryption architecture called MKTME. The memory encryption hardware underpinning MKTME is also used for Intel TDX. TDX ends up "stealing" some of the physical address space from the MKTME architecture for crypto-protection to VMs. The BIOS is responsible for partitioning the "KeyID" space between legacy MKTME and TDX. The KeyIDs reserved for TDX are called 'TDX private KeyIDs' or 'TDX KeyIDs' for short. TDX doesn't trust the BIOS. During machine boot, TDX verifies the TDX private KeyIDs are consistently and correctly programmed by the BIOS across all CPU packages before it enables TDX on any CPU core. A valid TDX private KeyID range on BSP indicates TDX has been enabled by the BIOS, otherwise the BIOS is buggy. The TDX module is expected to be loaded by the BIOS when it enables TDX, but the kernel needs to properly initialize it before it can be used to create and run any TDX guests. The TDX module will be initialized by the KVM subsystem when KVM wants to use TDX. Add a new early_initcall(tdx_init) to detect the TDX private KeyIDs. Both TDX module initialization and creating TDX guest require to use TDX private KeyID. Also add a function to report whether TDX is enabled by the BIOS (TDX KeyID range is valid). Similar to AMD SME, kexec() will use it to determine whether cache flush is needed. To start to support TDX, create a new arch/x86/virt/vmx/tdx/tdx.c for TDX host kernel support. Add a new Kconfig option CONFIG_INTEL_TDX_HOST to opt-in TDX host kernel support (to distinguish with TDX guest kernel support). So far only KVM uses TDX. Make the new config option depend on KVM_INTEL. Reviewed-by: Kirill A. Shutemov Signed-off-by: Kai Huang --- v7 -> v8: (address Dave's comments) - Improved changelog: - "KVM user" -> "The TDX module will be initialized by KVM when ..." - Changed "tdx_int" part to "Just say what this patch is doing" - Fixed the last sentence of "kexec()" paragraph - detect_tdx() -> record_keyid_partitioning() - Improved how to calculate tdx_keyid_start. - tdx_keyid_num -> nr_tdx_keyids. - Improved dmesg printing. - Add comment to clear_tdx(). v6 -> v7: - No change. v5 -> v6: - Removed SEAMRR detection to make code simpler. - Removed the 'default N' in the KVM_TDX_HOST Kconfig (Kirill). - Changed to use 'obj-y' in arch/x86/virt/vmx/tdx/Makefile (Kirill). --- arch/x86/Kconfig | 12 +++++ arch/x86/Makefile | 2 + arch/x86/include/asm/tdx.h | 7 +++ arch/x86/virt/Makefile | 2 + arch/x86/virt/vmx/Makefile | 2 + arch/x86/virt/vmx/tdx/Makefile | 2 + arch/x86/virt/vmx/tdx/tdx.c | 90 ++++++++++++++++++++++++++++++++++ arch/x86/virt/vmx/tdx/tdx.h | 15 ++++++ 8 files changed, 132 insertions(+) create mode 100644 arch/x86/virt/Makefile create mode 100644 arch/x86/virt/vmx/Makefile create mode 100644 arch/x86/virt/vmx/tdx/Makefile create mode 100644 arch/x86/virt/vmx/tdx/tdx.c create mode 100644 arch/x86/virt/vmx/tdx/tdx.h diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 67745ceab0db..cced4ef3bfb2 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1953,6 +1953,18 @@ config X86_SGX If unsure, say N. +config INTEL_TDX_HOST + bool "Intel Trust Domain Extensions (TDX) host support" + depends on CPU_SUP_INTEL + depends on X86_64 + depends on KVM_INTEL + help + Intel Trust Domain Extensions (TDX) protects guest VMs from malicious + host and certain physical attacks. This option enables necessary TDX + support in host kernel to run protected VMs. + + If unsure, say N. + config EFI bool "EFI runtime service support" depends on ACPI diff --git a/arch/x86/Makefile b/arch/x86/Makefile index 415a5d138de4..38d3e8addc5f 100644 --- a/arch/x86/Makefile +++ b/arch/x86/Makefile @@ -246,6 +246,8 @@ archheaders: libs-y += arch/x86/lib/ +core-y += arch/x86/virt/ + # drivers-y are linked after core-y drivers-$(CONFIG_MATH_EMULATION) += arch/x86/math-emu/ drivers-$(CONFIG_PCI) += arch/x86/pci/ diff --git a/arch/x86/include/asm/tdx.h b/arch/x86/include/asm/tdx.h index 25fd6070dc0b..4dfe2e794411 100644 --- a/arch/x86/include/asm/tdx.h +++ b/arch/x86/include/asm/tdx.h @@ -94,5 +94,12 @@ static inline long tdx_kvm_hypercall(unsigned int nr, unsigned long p1, return -ENODEV; } #endif /* CONFIG_INTEL_TDX_GUEST && CONFIG_KVM_GUEST */ + +#ifdef CONFIG_INTEL_TDX_HOST +bool platform_tdx_enabled(void); +#else /* !CONFIG_INTEL_TDX_HOST */ +static inline bool platform_tdx_enabled(void) { return false; } +#endif /* CONFIG_INTEL_TDX_HOST */ + #endif /* !__ASSEMBLY__ */ #endif /* _ASM_X86_TDX_H */ diff --git a/arch/x86/virt/Makefile b/arch/x86/virt/Makefile new file mode 100644 index 000000000000..1e36502cd738 --- /dev/null +++ b/arch/x86/virt/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-y += vmx/ diff --git a/arch/x86/virt/vmx/Makefile b/arch/x86/virt/vmx/Makefile new file mode 100644 index 000000000000..feebda21d793 --- /dev/null +++ b/arch/x86/virt/vmx/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-$(CONFIG_INTEL_TDX_HOST) += tdx/ diff --git a/arch/x86/virt/vmx/tdx/Makefile b/arch/x86/virt/vmx/tdx/Makefile new file mode 100644 index 000000000000..93ca8b73e1f1 --- /dev/null +++ b/arch/x86/virt/vmx/tdx/Makefile @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +obj-y += tdx.o diff --git a/arch/x86/virt/vmx/tdx/tdx.c b/arch/x86/virt/vmx/tdx/tdx.c new file mode 100644 index 000000000000..292852773ced --- /dev/null +++ b/arch/x86/virt/vmx/tdx/tdx.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright(c) 2022 Intel Corporation. + * + * Intel Trusted Domain Extensions (TDX) support + */ + +#define pr_fmt(fmt) "tdx: " fmt + +#include +#include +#include +#include +#include +#include +#include +#include "tdx.h" + +static u32 tdx_keyid_start __ro_after_init; +static u32 nr_tdx_keyids __ro_after_init; + +/* + * tdx_keyid_start and nr_tdx_keyids indicate that TDX is uninitialized. + * This is used in TDX initialization error paths to take it from + * initialized -> uninitialized. + */ +static void __init clear_tdx(void) +{ + tdx_keyid_start = nr_tdx_keyids = 0; +} + +static int __init record_keyid_partitioning(void) +{ + u32 nr_mktme_keyids; + int ret; + + /* + * IA32_MKTME_KEYID_PARTIONING: + * Bit [31:0]: Number of MKTME KeyIDs. + * Bit [63:32]: Number of TDX private KeyIDs. + */ + ret = rdmsr_safe(MSR_IA32_MKTME_KEYID_PARTITIONING, &nr_mktme_keyids, + &nr_tdx_keyids); + if (ret) + return -ENODEV; + + if (!nr_tdx_keyids) + return -ENODEV; + + /* TDX KeyIDs start after the last MKTME KeyID. */ + tdx_keyid_start = nr_mktme_keyids + 1; + + pr_info("BIOS enabled: private KeyID range [%u, %u)\n", + tdx_keyid_start, tdx_keyid_start + nr_tdx_keyids); + + return 0; +} + +static int __init tdx_init(void) +{ + int err; + + err = record_keyid_partitioning(); + if (err) + return err; + + /* + * Initializing the TDX module requires one TDX private KeyID. + * If there's only one TDX KeyID then after module initialization + * KVM won't be able to run any TDX guest, which makes the whole + * thing worthless. Just disable TDX in this case. + */ + if (nr_tdx_keyids < 2) { + pr_info("initialization failed: too few private KeyIDs available (%d).\n", + nr_tdx_keyids); + goto no_tdx; + } + + return 0; +no_tdx: + clear_tdx(); + return -ENODEV; +} +early_initcall(tdx_init); + +/* Return whether the BIOS has enabled TDX */ +bool platform_tdx_enabled(void) +{ + return !!nr_tdx_keyids; +} diff --git a/arch/x86/virt/vmx/tdx/tdx.h b/arch/x86/virt/vmx/tdx/tdx.h new file mode 100644 index 000000000000..d00074abcb20 --- /dev/null +++ b/arch/x86/virt/vmx/tdx/tdx.h @@ -0,0 +1,15 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _X86_VIRT_TDX_H +#define _X86_VIRT_TDX_H + +/* + * This file contains both macros and data structures defined by the TDX + * architecture and Linux defined software data structures and functions. + * The two should not be mixed together for better readability. The + * architectural definitions come first. + */ + +/* MSR to report KeyID partitioning between MKTME and TDX */ +#define MSR_IA32_MKTME_KEYID_PARTITIONING 0x00000087 + +#endif