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112 lines
2.2 KiB
112 lines
2.2 KiB
/* SPDX-License-Identifier: GPL-2.0-only */ |
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/* |
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* AMD Memory Encryption Support |
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* |
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* Copyright (C) 2017 Advanced Micro Devices, Inc. |
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* |
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* Author: Tom Lendacky <thomas.lendacky@amd.com> |
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*/ |
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#include <linux/linkage.h> |
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#include <asm/processor-flags.h> |
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#include <asm/msr.h> |
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#include <asm/asm-offsets.h> |
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.text |
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.code32 |
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SYM_FUNC_START(get_sev_encryption_bit) |
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xor %eax, %eax |
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#ifdef CONFIG_AMD_MEM_ENCRYPT |
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push %ebx |
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push %ecx |
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push %edx |
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movl $0x80000000, %eax /* CPUID to check the highest leaf */ |
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cpuid |
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cmpl $0x8000001f, %eax /* See if 0x8000001f is available */ |
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jb .Lno_sev |
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/* |
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* Check for the SEV feature: |
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* CPUID Fn8000_001F[EAX] - Bit 1 |
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* CPUID Fn8000_001F[EBX] - Bits 5:0 |
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* Pagetable bit position used to indicate encryption |
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*/ |
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movl $0x8000001f, %eax |
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cpuid |
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bt $1, %eax /* Check if SEV is available */ |
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jnc .Lno_sev |
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movl $MSR_AMD64_SEV, %ecx /* Read the SEV MSR */ |
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rdmsr |
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bt $MSR_AMD64_SEV_ENABLED_BIT, %eax /* Check if SEV is active */ |
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jnc .Lno_sev |
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movl %ebx, %eax |
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andl $0x3f, %eax /* Return the encryption bit location */ |
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jmp .Lsev_exit |
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.Lno_sev: |
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xor %eax, %eax |
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.Lsev_exit: |
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pop %edx |
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pop %ecx |
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pop %ebx |
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#endif /* CONFIG_AMD_MEM_ENCRYPT */ |
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ret |
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SYM_FUNC_END(get_sev_encryption_bit) |
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.code64 |
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#include "../../kernel/sev_verify_cbit.S" |
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SYM_FUNC_START(set_sev_encryption_mask) |
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#ifdef CONFIG_AMD_MEM_ENCRYPT |
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push %rbp |
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push %rdx |
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movq %rsp, %rbp /* Save current stack pointer */ |
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call get_sev_encryption_bit /* Get the encryption bit position */ |
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testl %eax, %eax |
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jz .Lno_sev_mask |
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bts %rax, sme_me_mask(%rip) /* Create the encryption mask */ |
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/* |
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* Read MSR_AMD64_SEV again and store it to sev_status. Can't do this in |
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* get_sev_encryption_bit() because this function is 32-bit code and |
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* shared between 64-bit and 32-bit boot path. |
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*/ |
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movl $MSR_AMD64_SEV, %ecx /* Read the SEV MSR */ |
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rdmsr |
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/* Store MSR value in sev_status */ |
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shlq $32, %rdx |
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orq %rdx, %rax |
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movq %rax, sev_status(%rip) |
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.Lno_sev_mask: |
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movq %rbp, %rsp /* Restore original stack pointer */ |
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pop %rdx |
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pop %rbp |
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#endif |
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xor %rax, %rax |
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ret |
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SYM_FUNC_END(set_sev_encryption_mask) |
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.data |
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#ifdef CONFIG_AMD_MEM_ENCRYPT |
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.balign 8 |
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SYM_DATA(sme_me_mask, .quad 0) |
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SYM_DATA(sev_status, .quad 0) |
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SYM_DATA(sev_check_data, .quad 0) |
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#endif
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