From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 87A19CCA47C for ; Tue, 14 Jun 2022 12:03:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356597AbiFNMD0 (ORCPT ); Tue, 14 Jun 2022 08:03:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54398 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1356279AbiFNMCq (ORCPT ); Tue, 14 Jun 2022 08:02:46 -0400 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F2D519032; Tue, 14 Jun 2022 05:02:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1655208163; x=1686744163; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=osAsv6UVE+6nsQGbK3e34qgPjlvTm/Mjt61vlC9yscs=; b=OnXGTPpQcotuupJ0mLcD6VlY/I9Cq0OFFd85NzQr7ymBuYdrxG2AfPej Bc0xl9qsy2U73T/4JldC0nv/KY4qQ4v+N6z0Jc4FiD96uf4d79O2MRaOb o8DT/2+qp8bhYbh6V2c+RQVa96Ne+em5RDU6uxJo1kNXWcUD8PRQ8Pr1z kZ0FY9ePoOOOE11Aq9O8XXZIJ4gKCli34xBkU7b8Y8KCg+zt66sk4LlnS OkpTkHx4fYAPF5it67iS6Ibu8CRGQfcrI9Rc4BVV6OTDQdR4SkGulaVF1 iXfq2rYyOc9hIN5IVDHJ5WC38zg6xHiVX4UKMaWMP+HnJoEbEYpEVgllB g==; X-IronPort-AV: E=McAfee;i="6400,9594,10377"; a="304007633" X-IronPort-AV: E=Sophos;i="5.91,300,1647327600"; d="scan'208";a="304007633" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Jun 2022 05:02:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.91,300,1647327600"; d="scan'208";a="652001295" Received: from black.fi.intel.com ([10.237.72.28]) by fmsmga004.fm.intel.com with ESMTP; 14 Jun 2022 05:02:36 -0700 Received: by black.fi.intel.com (Postfix, from userid 1000) id ACA37710; Tue, 14 Jun 2022 15:02:32 +0300 (EEST) From: "Kirill A. Shutemov" To: Borislav Petkov , Andy Lutomirski , Sean Christopherson , Andrew Morton , Joerg Roedel , Ard Biesheuvel Cc: Andi Kleen , Kuppuswamy Sathyanarayanan , David Rientjes , Vlastimil Babka , Tom Lendacky , Thomas Gleixner , Peter Zijlstra , Paolo Bonzini , Ingo Molnar , Varad Gautam , Dario Faggioli , Dave Hansen , Mike Rapoport , David Hildenbrand , marcelo.cerri@canonical.com, tim.gardner@canonical.com, khalid.elmously@canonical.com, philip.cox@canonical.com, x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, "Kirill A. Shutemov" Subject: [PATCHv7 06/14] efi/x86: Implement support for unaccepted memory Date: Tue, 14 Jun 2022 15:02:23 +0300 Message-Id: <20220614120231.48165-7-kirill.shutemov@linux.intel.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220614120231.48165-1-kirill.shutemov@linux.intel.com> References: <20220614120231.48165-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org UEFI Specification version 2.9 introduces the concept of memory acceptance: Some Virtual Machine platforms, such as Intel TDX or AMD SEV-SNP, requiring memory to be accepted before it can be used by the guest. Accepting happens via a protocol specific for the Virtual Machine platform. Accepting memory is costly and it makes VMM allocate memory for the accepted guest physical address range. It's better to postpone memory acceptance until memory is needed. It lowers boot time and reduces memory overhead. The kernel needs to know what memory has been accepted. Firmware communicates this information via memory map: a new memory type -- EFI_UNACCEPTED_MEMORY -- indicates such memory. Range-based tracking works fine for firmware, but it gets bulky for the kernel: e820 has to be modified on every page acceptance. It leads to table fragmentation, but there's a limited number of entries in the e820 table Another option is to mark such memory as usable in e820 and track if the range has been accepted in a bitmap. One bit in the bitmap represents 2MiB in the address space: one 4k page is enough to track 64GiB or physical address space. In the worst-case scenario -- a huge hole in the middle of the address space -- It needs 256MiB to handle 4PiB of the address space. Any unaccepted memory that is not aligned to 2M gets accepted upfront. The bitmap is allocated and constructed in the EFI stub and passed down to the kernel via boot_params. allocate_e820() allocates the bitmap if unaccepted memory is present, according to the maximum address in the memory map. The same boot_params.unaccepted_memory can be used to pass the bitmap between two kernels on kexec, but the use-case is not yet implemented. The implementation requires some basic helpers in boot stub. They provided by linux/ includes in the main kernel image, but is not present in boot stub. Create copy of required functionality in the boot stub. Signed-off-by: Kirill A. Shutemov --- Documentation/x86/zero-page.rst | 1 + arch/x86/boot/compressed/Makefile | 1 + arch/x86/boot/compressed/mem.c | 68 ++++++++++++++++++++++++ arch/x86/include/asm/unaccepted_memory.h | 10 ++++ arch/x86/include/uapi/asm/bootparam.h | 2 +- drivers/firmware/efi/Kconfig | 14 +++++ drivers/firmware/efi/efi.c | 1 + drivers/firmware/efi/libstub/x86-stub.c | 68 ++++++++++++++++++++++++ include/linux/efi.h | 3 +- 9 files changed, 166 insertions(+), 2 deletions(-) create mode 100644 arch/x86/boot/compressed/mem.c create mode 100644 arch/x86/include/asm/unaccepted_memory.h diff --git a/Documentation/x86/zero-page.rst b/Documentation/x86/zero-page.rst index 45aa9cceb4f1..f21905e61ade 100644 --- a/Documentation/x86/zero-page.rst +++ b/Documentation/x86/zero-page.rst @@ -20,6 +20,7 @@ Offset/Size Proto Name Meaning 060/010 ALL ist_info Intel SpeedStep (IST) BIOS support information (struct ist_info) 070/008 ALL acpi_rsdp_addr Physical address of ACPI RSDP table +078/008 ALL unaccepted_memory Bitmap of unaccepted memory (1bit == 2M) 080/010 ALL hd0_info hd0 disk parameter, OBSOLETE!! 090/010 ALL hd1_info hd1 disk parameter, OBSOLETE!! 0A0/010 ALL sys_desc_table System description table (struct sys_desc_table), diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 19e1905dcbf6..67732478323f 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -102,6 +102,7 @@ endif vmlinux-objs-$(CONFIG_ACPI) += $(obj)/acpi.o vmlinux-objs-$(CONFIG_INTEL_TDX_GUEST) += $(obj)/tdx.o $(obj)/tdcall.o +vmlinux-objs-$(CONFIG_UNACCEPTED_MEMORY) += $(obj)/bitmap.o $(obj)/mem.o vmlinux-objs-$(CONFIG_EFI_MIXED) += $(obj)/efi_thunk_$(BITS).o vmlinux-objs-$(CONFIG_EFI) += $(obj)/efi.o diff --git a/arch/x86/boot/compressed/mem.c b/arch/x86/boot/compressed/mem.c new file mode 100644 index 000000000000..415df0d3bc81 --- /dev/null +++ b/arch/x86/boot/compressed/mem.c @@ -0,0 +1,68 @@ +// SPDX-License-Identifier: GPL-2.0-only + +#include "../cpuflags.h" +#include "bitmap.h" +#include "error.h" +#include "math.h" + +#define PMD_SHIFT 21 +#define PMD_SIZE (_AC(1, UL) << PMD_SHIFT) +#define PMD_MASK (~(PMD_SIZE - 1)) + +static inline void __accept_memory(phys_addr_t start, phys_addr_t end) +{ + /* Platform-specific memory-acceptance call goes here */ + error("Cannot accept memory"); +} + +/* + * The accepted memory bitmap only works at PMD_SIZE granularity. If a request + * comes in to mark memory as unaccepted which is not PMD_SIZE-aligned, simply + * accept the memory now since it can not be *marked* as unaccepted. + */ +void process_unaccepted_memory(struct boot_params *params, u64 start, u64 end) +{ + /* + * Accept small regions that might not be able to be represented + * in the bitmap. This is a bit imprecise and may accept some + * areas that could have been represented in the bitmap instead. + * + * Consider case like this: + * + * | 4k | 2044k | 2048k | + * ^ 0x0 ^ 2MB ^ 4MB + * + * all memory in the range is unaccepted, except for the first 4k. + * The second 2M can be represented in the bitmap, but kernel accept it + * right away. The imprecision makes the code simpler by ensuring that + * at least one bit will be set int the bitmap below. + */ + if (end - start < 2 * PMD_SIZE) { + __accept_memory(start, end); + return; + } + + /* + * No matter how the start and end are aligned, at least one unaccepted + * PMD_SIZE area will remain. + */ + + /* Immediately accept a unaccepted_memory, + start / PMD_SIZE, (end - start) / PMD_SIZE); +} diff --git a/arch/x86/include/asm/unaccepted_memory.h b/arch/x86/include/asm/unaccepted_memory.h new file mode 100644 index 000000000000..df0736d32858 --- /dev/null +++ b/arch/x86/include/asm/unaccepted_memory.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2020 Intel Corporation */ +#ifndef _ASM_X86_UNACCEPTED_MEMORY_H +#define _ASM_X86_UNACCEPTED_MEMORY_H + +struct boot_params; + +void process_unaccepted_memory(struct boot_params *params, u64 start, u64 num); + +#endif diff --git a/arch/x86/include/uapi/asm/bootparam.h b/arch/x86/include/uapi/asm/bootparam.h index bea5cdcdf532..c62f6ee4b6f0 100644 --- a/arch/x86/include/uapi/asm/bootparam.h +++ b/arch/x86/include/uapi/asm/bootparam.h @@ -180,7 +180,7 @@ struct boot_params { __u64 tboot_addr; /* 0x058 */ struct ist_info ist_info; /* 0x060 */ __u64 acpi_rsdp_addr; /* 0x070 */ - __u8 _pad3[8]; /* 0x078 */ + __u64 unaccepted_memory; /* 0x078 */ __u8 hd0_info[16]; /* obsolete! */ /* 0x080 */ __u8 hd1_info[16]; /* obsolete! */ /* 0x090 */ struct sys_desc_table sys_desc_table; /* obsolete! */ /* 0x0a0 */ diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig index 7aa4717cdcac..e1270beff4dc 100644 --- a/drivers/firmware/efi/Kconfig +++ b/drivers/firmware/efi/Kconfig @@ -305,6 +305,20 @@ config EFI_COCO_SECRET virt/coco/efi_secret module to access the secrets, which in turn allows userspace programs to access the injected secrets. +config UNACCEPTED_MEMORY + bool + depends on EFI_STUB + help + Some Virtual Machine platforms, such as Intel TDX, require + some memory to be "accepted" by the guest before it can be used. + This mechanism helps prevent malicious hosts from making changes + to guest memory. + + UEFI specification v2.9 introduced EFI_UNACCEPTED_MEMORY memory type. + + This option adds support for unaccepted memory and makes such memory + usable by the kernel. + config EFI_EMBEDDED_FIRMWARE bool select CRYPTO_LIB_SHA256 diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c index 860534bcfdac..34d1ca870420 100644 --- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -758,6 +758,7 @@ static __initdata char memory_type_name[][13] = { "MMIO Port", "PAL Code", "Persistent", + "Unaccepted", }; char * __init efi_md_typeattr_format(char *buf, size_t size, diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index 504955368934..b91c89100b2d 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -15,6 +15,7 @@ #include #include #include +#include #include "efistub.h" @@ -607,6 +608,17 @@ setup_e820(struct boot_params *params, struct setup_data *e820ext, u32 e820ext_s e820_type = E820_TYPE_PMEM; break; + case EFI_UNACCEPTED_MEMORY: + if (!IS_ENABLED(CONFIG_UNACCEPTED_MEMORY)) { + efi_warn_once("The system has unaccepted memory," + " but kernel does not support it\n"); + efi_warn_once("Consider enabling CONFIG_UNACCEPTED_MEMORY\n"); + continue; + } + e820_type = E820_TYPE_RAM; + process_unaccepted_memory(params, d->phys_addr, + d->phys_addr + PAGE_SIZE * d->num_pages); + break; default: continue; } @@ -671,6 +683,59 @@ static efi_status_t alloc_e820ext(u32 nr_desc, struct setup_data **e820ext, return status; } +static efi_status_t allocate_unaccepted_memory(struct boot_params *params, + __u32 nr_desc, + struct efi_boot_memmap *map) +{ + unsigned long *mem = NULL; + u64 size, max_addr = 0; + efi_status_t status; + bool found = false; + int i; + + /* Check if there's any unaccepted memory and find the max address */ + for (i = 0; i < nr_desc; i++) { + efi_memory_desc_t *d; + + d = efi_early_memdesc_ptr(*map->map, *map->desc_size, i); + if (d->type == EFI_UNACCEPTED_MEMORY) + found = true; + if (d->phys_addr + d->num_pages * PAGE_SIZE > max_addr) + max_addr = d->phys_addr + d->num_pages * PAGE_SIZE; + } + + if (!found) { + params->unaccepted_memory = 0; + return EFI_SUCCESS; + } + + /* + * If unaccepted memory is present allocate a bitmap to track what + * memory has to be accepted before access. + * + * One bit in the bitmap represents 2MiB in the address space: + * A 4k bitmap can track 64GiB of physical address space. + * + * In the worst case scenario -- a huge hole in the middle of the + * address space -- It needs 256MiB to handle 4PiB of the address + * space. + * + * TODO: handle situation if params->unaccepted_memory is already set. + * It's required to deal with kexec. + * + * The bitmap will be populated in setup_e820() according to the memory + * map after efi_exit_boot_services(). + */ + size = DIV_ROUND_UP(max_addr, PMD_SIZE * BITS_PER_BYTE); + status = efi_allocate_pages(size, (unsigned long *)&mem, ULONG_MAX); + if (status == EFI_SUCCESS) { + memset(mem, 0, size); + params->unaccepted_memory = (unsigned long)mem; + } + + return status; +} + static efi_status_t allocate_e820(struct boot_params *params, struct efi_boot_memmap *map, struct setup_data **e820ext, @@ -691,6 +756,9 @@ static efi_status_t allocate_e820(struct boot_params *params, status = alloc_e820ext(nr_e820ext, e820ext, e820ext_size); } + if (IS_ENABLED(CONFIG_UNACCEPTED_MEMORY) && status == EFI_SUCCESS) + status = allocate_unaccepted_memory(params, nr_desc, map); + efi_bs_call(free_pool, *map->map); return status; } diff --git a/include/linux/efi.h b/include/linux/efi.h index 7d9b0bb47eb3..9c2fa94f2f93 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -108,7 +108,8 @@ typedef struct { #define EFI_MEMORY_MAPPED_IO_PORT_SPACE 12 #define EFI_PAL_CODE 13 #define EFI_PERSISTENT_MEMORY 14 -#define EFI_MAX_MEMORY_TYPE 15 +#define EFI_UNACCEPTED_MEMORY 15 +#define EFI_MAX_MEMORY_TYPE 16 /* Attribute values: */ #define EFI_MEMORY_UC ((u64)0x0000000000000001ULL) /* uncached */ -- 2.35.1