From 7f8b7e7f4ccbbd1fb8badddfabd28c955aea87b4 Mon Sep 17 00:00:00 2001 From: Tom Lendacky Date: Mon, 17 Jul 2017 16:10:10 -0500 Subject: [PATCH] x86/mm: Add support for early encryption/decryption of memory MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add support to be able to either encrypt or decrypt data in place during the early stages of booting the kernel. This does not change the memory encryption attribute - it is used for ensuring that data present in either an encrypted or decrypted memory area is in the proper state (for example the initrd will have been loaded by the boot loader and will not be encrypted, but the memory that it resides in is marked as encrypted). Signed-off-by: Tom Lendacky Reviewed-by: Thomas Gleixner Reviewed-by: Borislav Petkov Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Borislav Petkov Cc: Brijesh Singh Cc: Dave Young Cc: Dmitry Vyukov Cc: Jonathan Corbet Cc: Konrad Rzeszutek Wilk Cc: Larry Woodman Cc: Linus Torvalds Cc: Matt Fleming Cc: Michael S. Tsirkin Cc: Paolo Bonzini Cc: Peter Zijlstra Cc: Radim Krčmář Cc: Rik van Riel Cc: Toshimitsu Kani Cc: kasan-dev@googlegroups.com Cc: kvm@vger.kernel.org Cc: linux-arch@vger.kernel.org Cc: linux-doc@vger.kernel.org Cc: linux-efi@vger.kernel.org Cc: linux-mm@kvack.org Link: http://lkml.kernel.org/r/f9968e9432cd6c4b57ef245729be04ff18852225.1500319216.git.thomas.lendacky@amd.com Signed-off-by: Ingo Molnar --- arch/x86/include/asm/mem_encrypt.h | 10 +++++ arch/x86/mm/mem_encrypt.c | 76 ++++++++++++++++++++++++++++++++++++++ 2 files changed, 86 insertions(+) diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h index dbae7a5..8baa35b 100644 --- a/arch/x86/include/asm/mem_encrypt.h +++ b/arch/x86/include/asm/mem_encrypt.h @@ -21,6 +21,11 @@ extern unsigned long sme_me_mask; +void __init sme_early_encrypt(resource_size_t paddr, + unsigned long size); +void __init sme_early_decrypt(resource_size_t paddr, + unsigned long size); + void __init sme_early_init(void); void __init sme_encrypt_kernel(void); @@ -30,6 +35,11 @@ void __init sme_enable(void); #define sme_me_mask 0UL +static inline void __init sme_early_encrypt(resource_size_t paddr, + unsigned long size) { } +static inline void __init sme_early_decrypt(resource_size_t paddr, + unsigned long size) { } + static inline void __init sme_early_init(void) { } static inline void __init sme_encrypt_kernel(void) { } diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index f973d3d..54bb73c 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -14,6 +14,9 @@ #include #include +#include +#include + /* * Since SME related variables are set early in the boot process they must * reside in the .data section so as not to be zeroed out when the .bss @@ -22,6 +25,79 @@ unsigned long sme_me_mask __section(.data) = 0; EXPORT_SYMBOL_GPL(sme_me_mask); +/* Buffer used for early in-place encryption by BSP, no locking needed */ +static char sme_early_buffer[PAGE_SIZE] __aligned(PAGE_SIZE); + +/* + * This routine does not change the underlying encryption setting of the + * page(s) that map this memory. It assumes that eventually the memory is + * meant to be accessed as either encrypted or decrypted but the contents + * are currently not in the desired state. + * + * This routine follows the steps outlined in the AMD64 Architecture + * Programmer's Manual Volume 2, Section 7.10.8 Encrypt-in-Place. + */ +static void __init __sme_early_enc_dec(resource_size_t paddr, + unsigned long size, bool enc) +{ + void *src, *dst; + size_t len; + + if (!sme_me_mask) + return; + + local_flush_tlb(); + wbinvd(); + + /* + * There are limited number of early mapping slots, so map (at most) + * one page at time. + */ + while (size) { + len = min_t(size_t, sizeof(sme_early_buffer), size); + + /* + * Create mappings for the current and desired format of + * the memory. Use a write-protected mapping for the source. + */ + src = enc ? early_memremap_decrypted_wp(paddr, len) : + early_memremap_encrypted_wp(paddr, len); + + dst = enc ? early_memremap_encrypted(paddr, len) : + early_memremap_decrypted(paddr, len); + + /* + * If a mapping can't be obtained to perform the operation, + * then eventual access of that area in the desired mode + * will cause a crash. + */ + BUG_ON(!src || !dst); + + /* + * Use a temporary buffer, of cache-line multiple size, to + * avoid data corruption as documented in the APM. + */ + memcpy(sme_early_buffer, src, len); + memcpy(dst, sme_early_buffer, len); + + early_memunmap(dst, len); + early_memunmap(src, len); + + paddr += len; + size -= len; + } +} + +void __init sme_early_encrypt(resource_size_t paddr, unsigned long size) +{ + __sme_early_enc_dec(paddr, size, true); +} + +void __init sme_early_decrypt(resource_size_t paddr, unsigned long size) +{ + __sme_early_enc_dec(paddr, size, false); +} + void __init sme_early_init(void) { unsigned int i; -- 2.7.4