diff options
Diffstat (limited to 'arch/x86/boot/compressed/mem_encrypt.S')
| -rw-r--r-- | arch/x86/boot/compressed/mem_encrypt.S | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/arch/x86/boot/compressed/mem_encrypt.S b/arch/x86/boot/compressed/mem_encrypt.S new file mode 100644 index 000000000..a480356e0 --- /dev/null +++ b/arch/x86/boot/compressed/mem_encrypt.S @@ -0,0 +1,104 @@ +/* + * AMD Memory Encryption Support + * + * Copyright (C) 2017 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/processor-flags.h> +#include <asm/msr.h> +#include <asm/asm-offsets.h> + + .text + .code32 +ENTRY(get_sev_encryption_bit) + xor %eax, %eax + +#ifdef CONFIG_AMD_MEM_ENCRYPT + push %ebx + push %ecx + push %edx + + /* Check if running under a hypervisor */ + movl $1, %eax + cpuid + bt $31, %ecx /* Check the hypervisor bit */ + jnc .Lno_sev + + movl $0x80000000, %eax /* CPUID to check the highest leaf */ + cpuid + cmpl $0x8000001f, %eax /* See if 0x8000001f is available */ + jb .Lno_sev + + /* + * Check for the SEV feature: + * CPUID Fn8000_001F[EAX] - Bit 1 + * CPUID Fn8000_001F[EBX] - Bits 5:0 + * Pagetable bit position used to indicate encryption + */ + movl $0x8000001f, %eax + cpuid + bt $1, %eax /* Check if SEV is available */ + jnc .Lno_sev + + movl $MSR_AMD64_SEV, %ecx /* Read the SEV MSR */ + rdmsr + bt $MSR_AMD64_SEV_ENABLED_BIT, %eax /* Check if SEV is active */ + jnc .Lno_sev + + movl %ebx, %eax + andl $0x3f, %eax /* Return the encryption bit location */ + jmp .Lsev_exit + +.Lno_sev: + xor %eax, %eax + +.Lsev_exit: + pop %edx + pop %ecx + pop %ebx + +#endif /* CONFIG_AMD_MEM_ENCRYPT */ + + ret +ENDPROC(get_sev_encryption_bit) + + .code64 +ENTRY(set_sev_encryption_mask) +#ifdef CONFIG_AMD_MEM_ENCRYPT + push %rbp + push %rdx + + movq %rsp, %rbp /* Save current stack pointer */ + + call get_sev_encryption_bit /* Get the encryption bit position */ + testl %eax, %eax + jz .Lno_sev_mask + + bts %rax, sme_me_mask(%rip) /* Create the encryption mask */ + +.Lno_sev_mask: + movq %rbp, %rsp /* Restore original stack pointer */ + + pop %rdx + pop %rbp +#endif + + xor %rax, %rax + ret +ENDPROC(set_sev_encryption_mask) + + .data + +#ifdef CONFIG_AMD_MEM_ENCRYPT + .balign 8 +GLOBAL(sme_me_mask) + .quad 0 +#endif |