diff options
| -rw-r--r-- | arch/x86/include/asm/mem_encrypt.h | 6 | ||||
| -rw-r--r-- | arch/x86/mm/Makefile | 1 | ||||
| -rw-r--r-- | arch/x86/mm/mem_encrypt.c | 310 | ||||
| -rw-r--r-- | arch/x86/mm/mem_encrypt_boot.S | 149 |
4 files changed, 466 insertions, 0 deletions
diff --git a/arch/x86/include/asm/mem_encrypt.h b/arch/x86/include/asm/mem_encrypt.h index 70e55f6b9adf..7122c365c2a3 100644 --- a/arch/x86/include/asm/mem_encrypt.h +++ b/arch/x86/include/asm/mem_encrypt.h @@ -21,6 +21,12 @@ extern unsigned long sme_me_mask; +void sme_encrypt_execute(unsigned long encrypted_kernel_vaddr, + unsigned long decrypted_kernel_vaddr, + unsigned long kernel_len, + unsigned long encryption_wa, + unsigned long encryption_pgd); + void __init sme_early_encrypt(resource_size_t paddr, unsigned long size); void __init sme_early_decrypt(resource_size_t paddr, diff --git a/arch/x86/mm/Makefile b/arch/x86/mm/Makefile index a94a7b663d5f..72bf8c01c6e3 100644 --- a/arch/x86/mm/Makefile +++ b/arch/x86/mm/Makefile @@ -40,3 +40,4 @@ obj-$(CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS) += pkeys.o obj-$(CONFIG_RANDOMIZE_MEMORY) += kaslr.o obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt.o +obj-$(CONFIG_AMD_MEM_ENCRYPT) += mem_encrypt_boot.o diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index a7400ec8538b..e5d543938b0f 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -21,6 +21,8 @@ #include <asm/setup.h> #include <asm/bootparam.h> #include <asm/set_memory.h> +#include <asm/cacheflush.h> +#include <asm/sections.h> /* * Since SME related variables are set early in the boot process they must @@ -199,8 +201,316 @@ void swiotlb_set_mem_attributes(void *vaddr, unsigned long size) set_memory_decrypted((unsigned long)vaddr, size >> PAGE_SHIFT); } +static void __init sme_clear_pgd(pgd_t *pgd_base, unsigned long start, + unsigned long end) +{ + unsigned long pgd_start, pgd_end, pgd_size; + pgd_t *pgd_p; + + pgd_start = start & PGDIR_MASK; + pgd_end = end & PGDIR_MASK; + + pgd_size = (((pgd_end - pgd_start) / PGDIR_SIZE) + 1); + pgd_size *= sizeof(pgd_t); + + pgd_p = pgd_base + pgd_index(start); + + memset(pgd_p, 0, pgd_size); +} + +#define PGD_FLAGS _KERNPG_TABLE_NOENC +#define P4D_FLAGS _KERNPG_TABLE_NOENC +#define PUD_FLAGS _KERNPG_TABLE_NOENC +#define PMD_FLAGS (__PAGE_KERNEL_LARGE_EXEC & ~_PAGE_GLOBAL) + +static void __init *sme_populate_pgd(pgd_t *pgd_base, void *pgtable_area, + unsigned long vaddr, pmdval_t pmd_val) +{ + pgd_t *pgd_p; + p4d_t *p4d_p; + pud_t *pud_p; + pmd_t *pmd_p; + + pgd_p = pgd_base + pgd_index(vaddr); + if (native_pgd_val(*pgd_p)) { + if (IS_ENABLED(CONFIG_X86_5LEVEL)) + p4d_p = (p4d_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK); + else + pud_p = (pud_t *)(native_pgd_val(*pgd_p) & ~PTE_FLAGS_MASK); + } else { + pgd_t pgd; + + if (IS_ENABLED(CONFIG_X86_5LEVEL)) { + p4d_p = pgtable_area; + memset(p4d_p, 0, sizeof(*p4d_p) * PTRS_PER_P4D); + pgtable_area += sizeof(*p4d_p) * PTRS_PER_P4D; + + pgd = native_make_pgd((pgdval_t)p4d_p + PGD_FLAGS); + } else { + pud_p = pgtable_area; + memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD); + pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD; + + pgd = native_make_pgd((pgdval_t)pud_p + PGD_FLAGS); + } + native_set_pgd(pgd_p, pgd); + } + + if (IS_ENABLED(CONFIG_X86_5LEVEL)) { + p4d_p += p4d_index(vaddr); + if (native_p4d_val(*p4d_p)) { + pud_p = (pud_t *)(native_p4d_val(*p4d_p) & ~PTE_FLAGS_MASK); + } else { + p4d_t p4d; + + pud_p = pgtable_area; + memset(pud_p, 0, sizeof(*pud_p) * PTRS_PER_PUD); + pgtable_area += sizeof(*pud_p) * PTRS_PER_PUD; + + p4d = native_make_p4d((pudval_t)pud_p + P4D_FLAGS); + native_set_p4d(p4d_p, p4d); + } + } + + pud_p += pud_index(vaddr); + if (native_pud_val(*pud_p)) { + if (native_pud_val(*pud_p) & _PAGE_PSE) + goto out; + + pmd_p = (pmd_t *)(native_pud_val(*pud_p) & ~PTE_FLAGS_MASK); + } else { + pud_t pud; + + pmd_p = pgtable_area; + memset(pmd_p, 0, sizeof(*pmd_p) * PTRS_PER_PMD); + pgtable_area += sizeof(*pmd_p) * PTRS_PER_PMD; + + pud = native_make_pud((pmdval_t)pmd_p + PUD_FLAGS); + native_set_pud(pud_p, pud); + } + + pmd_p += pmd_index(vaddr); + if (!native_pmd_val(*pmd_p) || !(native_pmd_val(*pmd_p) & _PAGE_PSE)) + native_set_pmd(pmd_p, native_make_pmd(pmd_val)); + +out: + return pgtable_area; +} + +static unsigned long __init sme_pgtable_calc(unsigned long len) +{ + unsigned long p4d_size, pud_size, pmd_size; + unsigned long total; + + /* + * Perform a relatively simplistic calculation of the pagetable + * entries that are needed. That mappings will be covered by 2MB + * PMD entries so we can conservatively calculate the required + * number of P4D, PUD and PMD structures needed to perform the + * mappings. Incrementing the count for each covers the case where + * the addresses cross entries. + */ + if (IS_ENABLED(CONFIG_X86_5LEVEL)) { + p4d_size = (ALIGN(len, PGDIR_SIZE) / PGDIR_SIZE) + 1; + p4d_size *= sizeof(p4d_t) * PTRS_PER_P4D; + pud_size = (ALIGN(len, P4D_SIZE) / P4D_SIZE) + 1; + pud_size *= sizeof(pud_t) * PTRS_PER_PUD; + } else { + p4d_size = 0; + pud_size = (ALIGN(len, PGDIR_SIZE) / PGDIR_SIZE) + 1; + pud_size *= sizeof(pud_t) * PTRS_PER_PUD; + } + pmd_size = (ALIGN(len, PUD_SIZE) / PUD_SIZE) + 1; + pmd_size *= sizeof(pmd_t) * PTRS_PER_PMD; + + total = p4d_size + pud_size + pmd_size; + + /* + * Now calculate the added pagetable structures needed to populate + * the new pagetables. + */ + if (IS_ENABLED(CONFIG_X86_5LEVEL)) { + p4d_size = ALIGN(total, PGDIR_SIZE) / PGDIR_SIZE; + p4d_size *= sizeof(p4d_t) * PTRS_PER_P4D; + pud_size = ALIGN(total, P4D_SIZE) / P4D_SIZE; + pud_size *= sizeof(pud_t) * PTRS_PER_PUD; + } else { + p4d_size = 0; + pud_size = ALIGN(total, PGDIR_SIZE) / PGDIR_SIZE; + pud_size *= sizeof(pud_t) * PTRS_PER_PUD; + } + pmd_size = ALIGN(total, PUD_SIZE) / PUD_SIZE; + pmd_size *= sizeof(pmd_t) * PTRS_PER_PMD; + + total += p4d_size + pud_size + pmd_size; + + return total; +} + void __init sme_encrypt_kernel(void) { + unsigned long workarea_start, workarea_end, workarea_len; + unsigned long execute_start, execute_end, execute_len; + unsigned long kernel_start, kernel_end, kernel_len; + unsigned long pgtable_area_len; + unsigned long paddr, pmd_flags; + unsigned long decrypted_base; + void *pgtable_area; + pgd_t *pgd; + + if (!sme_active()) + return; + + /* + * Prepare for encrypting the kernel by building new pagetables with + * the necessary attributes needed to encrypt the kernel in place. + * + * One range of virtual addresses will map the memory occupied + * by the kernel as encrypted. + * + * Another range of virtual addresses will map the memory occupied + * by the kernel as decrypted and write-protected. + * + * The use of write-protect attribute will prevent any of the + * memory from being cached. + */ + + /* Physical addresses gives us the identity mapped virtual addresses */ + kernel_start = __pa_symbol(_text); + kernel_end = ALIGN(__pa_symbol(_end), PMD_PAGE_SIZE); + kernel_len = kernel_end - kernel_start; + + /* Set the encryption workarea to be immediately after the kernel */ + workarea_start = kernel_end; + + /* + * Calculate required number of workarea bytes needed: + * executable encryption area size: + * stack page (PAGE_SIZE) + * encryption routine page (PAGE_SIZE) + * intermediate copy buffer (PMD_PAGE_SIZE) + * pagetable structures for the encryption of the kernel + * pagetable structures for workarea (in case not currently mapped) + */ + execute_start = workarea_start; + execute_end = execute_start + (PAGE_SIZE * 2) + PMD_PAGE_SIZE; + execute_len = execute_end - execute_start; + + /* + * One PGD for both encrypted and decrypted mappings and a set of + * PUDs and PMDs for each of the encrypted and decrypted mappings. + */ + pgtable_area_len = sizeof(pgd_t) * PTRS_PER_PGD; + pgtable_area_len += sme_pgtable_calc(execute_end - kernel_start) * 2; + + /* PUDs and PMDs needed in the current pagetables for the workarea */ + pgtable_area_len += sme_pgtable_calc(execute_len + pgtable_area_len); + + /* + * The total workarea includes the executable encryption area and + * the pagetable area. + */ + workarea_len = execute_len + pgtable_area_len; + workarea_end = workarea_start + workarea_len; + + /* + * Set the address to the start of where newly created pagetable + * structures (PGDs, PUDs and PMDs) will be allocated. New pagetable + * structures are created when the workarea is added to the current + * pagetables and when the new encrypted and decrypted kernel + * mappings are populated. + */ + pgtable_area = (void *)execute_end; + + /* + * Make sure the current pagetable structure has entries for + * addressing the workarea. + */ + pgd = (pgd_t *)native_read_cr3_pa(); + paddr = workarea_start; + while (paddr < workarea_end) { + pgtable_area = sme_populate_pgd(pgd, pgtable_area, + paddr, + paddr + PMD_FLAGS); + + paddr += PMD_PAGE_SIZE; + } + + /* Flush the TLB - no globals so cr3 is enough */ + native_write_cr3(__native_read_cr3()); + + /* + * A new pagetable structure is being built to allow for the kernel + * to be encrypted. It starts with an empty PGD that will then be + * populated with new PUDs and PMDs as the encrypted and decrypted + * kernel mappings are created. + */ + pgd = pgtable_area; + memset(pgd, 0, sizeof(*pgd) * PTRS_PER_PGD); + pgtable_area += sizeof(*pgd) * PTRS_PER_PGD; + + /* Add encrypted kernel (identity) mappings */ + pmd_flags = PMD_FLAGS | _PAGE_ENC; + paddr = kernel_start; + while (paddr < kernel_end) { + pgtable_area = sme_populate_pgd(pgd, pgtable_area, + paddr, + paddr + pmd_flags); + + paddr += PMD_PAGE_SIZE; + } + + /* + * A different PGD index/entry must be used to get different + * pagetable entries for the decrypted mapping. Choose the next + * PGD index and convert it to a virtual address to be used as + * the base of the mapping. + */ + decrypted_base = (pgd_index(workarea_end) + 1) & (PTRS_PER_PGD - 1); + decrypted_base <<= PGDIR_SHIFT; + + /* Add decrypted, write-protected kernel (non-identity) mappings */ + pmd_flags = (PMD_FLAGS & ~_PAGE_CACHE_MASK) | (_PAGE_PAT | _PAGE_PWT); + paddr = kernel_start; + while (paddr < kernel_end) { + pgtable_area = sme_populate_pgd(pgd, pgtable_area, + paddr + decrypted_base, + paddr + pmd_flags); + + paddr += PMD_PAGE_SIZE; + } + + /* Add decrypted workarea mappings to both kernel mappings */ + paddr = workarea_start; + while (paddr < workarea_end) { + pgtable_area = sme_populate_pgd(pgd, pgtable_area, + paddr, + paddr + PMD_FLAGS); + + pgtable_area = sme_populate_pgd(pgd, pgtable_area, + paddr + decrypted_base, + paddr + PMD_FLAGS); + + paddr += PMD_PAGE_SIZE; + } + + /* Perform the encryption */ + sme_encrypt_execute(kernel_start, kernel_start + decrypted_base, + kernel_len, workarea_start, (unsigned long)pgd); + + /* + * At this point we are running encrypted. Remove the mappings for + * the decrypted areas - all that is needed for this is to remove + * the PGD entry/entries. + */ + sme_clear_pgd(pgd, kernel_start + decrypted_base, + kernel_end + decrypted_base); + + sme_clear_pgd(pgd, workarea_start + decrypted_base, + workarea_end + decrypted_base); + + /* Flush the TLB - no globals so cr3 is enough */ + native_write_cr3(__native_read_cr3()); } void __init sme_enable(void) diff --git a/arch/x86/mm/mem_encrypt_boot.S b/arch/x86/mm/mem_encrypt_boot.S new file mode 100644 index 000000000000..b327e0472448 --- /dev/null +++ b/arch/x86/mm/mem_encrypt_boot.S @@ -0,0 +1,149 @@ +/* + * AMD Memory Encryption Support + * + * Copyright (C) 2016 Advanced Micro Devices, Inc. + * + * Author: Tom Lendacky <thomas.lendacky@amd.com> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/linkage.h> +#include <asm/pgtable.h> +#include <asm/page.h> +#include <asm/processor-flags.h> +#include <asm/msr-index.h> +#include <asm/frame.h> + + .text + .code64 +ENTRY(sme_encrypt_execute) + + /* + * Entry parameters: + * RDI - virtual address for the encrypted kernel mapping + * RSI - virtual address for the decrypted kernel mapping + * RDX - length of kernel + * RCX - virtual address of the encryption workarea, including: + * - stack page (PAGE_SIZE) + * - encryption routine page (PAGE_SIZE) + * - intermediate copy buffer (PMD_PAGE_SIZE) + * R8 - physcial address of the pagetables to use for encryption + */ + + FRAME_BEGIN /* RBP now has original stack pointer */ + + /* Set up a one page stack in the non-encrypted memory area */ + movq %rcx, %rax /* Workarea stack page */ + leaq PAGE_SIZE(%rax), %rsp /* Set new stack pointer */ + addq $PAGE_SIZE, %rax /* Workarea encryption routine */ + + push %r12 + movq %rdi, %r10 /* Encrypted kernel */ + movq %rsi, %r11 /* Decrypted kernel */ + movq %rdx, %r12 /* Kernel length */ + + /* Copy encryption routine into the workarea */ + movq %rax, %rdi /* Workarea encryption routine */ + leaq __enc_copy(%rip), %rsi /* Encryption routine */ + movq $(.L__enc_copy_end - __enc_copy), %rcx /* Encryption routine length */ + rep movsb + + /* Setup registers for call */ + movq %r10, %rdi /* Encrypted kernel */ + movq %r11, %rsi /* Decrypted kernel */ + movq %r8, %rdx /* Pagetables used for encryption */ + movq %r12, %rcx /* Kernel length */ + movq %rax, %r8 /* Workarea encryption routine */ + addq $PAGE_SIZE, %r8 /* Workarea intermediate copy buffer */ + + call *%rax /* Call the encryption routine */ + + pop %r12 + + movq %rbp, %rsp /* Restore original stack pointer */ + FRAME_END + + ret +ENDPROC(sme_encrypt_execute) + +ENTRY(__enc_copy) +/* + * Routine used to encrypt kernel. + * This routine must be run outside of the kernel proper since + * the kernel will be encrypted during the process. So this + * routine is defined here and then copied to an area outside + * of the kernel where it will remain and run decrypted + * during execution. + * + * On entry the registers must be: + * RDI - virtual address for the encrypted kernel mapping + * RSI - virtual address for the decrypted kernel mapping + * RDX - address of the pagetables to use for encryption + * RCX - length of kernel + * R8 - intermediate copy buffer + * + * RAX - points to this routine + * + * The kernel will be encrypted by copying from the non-encrypted + * kernel space to an intermediate buffer and then copying from the + * intermediate buffer back to the encrypted kernel space. The physical + * addresses of the two kernel space mappings are the same which + * results in the kernel being encrypted "in place". + */ + /* Enable the new page tables */ + mov %rdx, %cr3 + + /* Flush any global TLBs */ + mov %cr4, %rdx + andq $~X86_CR4_PGE, %rdx + mov %rdx, %cr4 + orq $X86_CR4_PGE, %rdx + mov %rdx, %cr4 + + /* Set the PAT register PA5 entry to write-protect */ + push %rcx + movl $MSR_IA32_CR_PAT, %ecx + rdmsr + push %rdx /* Save original PAT value */ + andl $0xffff00ff, %edx /* Clear PA5 */ + orl $0x00000500, %edx /* Set PA5 to WP */ + wrmsr + pop %rdx /* RDX contains original PAT value */ + pop %rcx + + movq %rcx, %r9 /* Save kernel length */ + movq %rdi, %r10 /* Save encrypted kernel address */ + movq %rsi, %r11 /* Save decrypted kernel address */ + + wbinvd /* Invalidate any cache entries */ + + /* Copy/encrypt 2MB at a time */ +1: + movq %r11, %rsi /* Source - decrypted kernel */ + movq %r8, %rdi /* Dest - intermediate copy buffer */ + movq $PMD_PAGE_SIZE, %rcx /* 2MB length */ + rep movsb + + movq %r8, %rsi /* Source - intermediate copy buffer */ + movq %r10, %rdi /* Dest - encrypted kernel */ + movq $PMD_PAGE_SIZE, %rcx /* 2MB length */ + rep movsb + + addq $PMD_PAGE_SIZE, %r11 + addq $PMD_PAGE_SIZE, %r10 + subq $PMD_PAGE_SIZE, %r9 /* Kernel length decrement */ + jnz 1b /* Kernel length not zero? */ + + /* Restore PAT register */ + push %rdx /* Save original PAT value */ + movl $MSR_IA32_CR_PAT, %ecx + rdmsr + pop %rdx /* Restore original PAT value */ + wrmsr + + ret +.L__enc_copy_end: +ENDPROC(__enc_copy) |