On Mon, Aug 22, 2016 at 05:39:08PM -0500, Tom Lendacky wrote: > This patch adds the support to check if SME has been enabled and if the > mem_encrypt=on command line option is set. If both of these conditions > are true, then the encryption mask is set and the kernel is encrypted > "in place." > > Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx> > --- > Documentation/kernel-parameters.txt | 3 > arch/x86/kernel/asm-offsets.c | 2 > arch/x86/kernel/mem_encrypt.S | 302 +++++++++++++++++++++++++++++++++++ > arch/x86/mm/mem_encrypt.c | 2 > 4 files changed, 309 insertions(+) > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 46c030a..a1986c8 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -2268,6 +2268,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > memory contents and reserves bad memory > regions that are detected. > > + mem_encrypt=on [X86_64] Enable memory encryption on processors > + that support this feature. > + > meye.*= [HW] Set MotionEye Camera parameters > See Documentation/video4linux/meye.txt. > > diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c > index 2bd5c6f..e485ada 100644 > --- a/arch/x86/kernel/asm-offsets.c > +++ b/arch/x86/kernel/asm-offsets.c > @@ -85,6 +85,8 @@ void common(void) { > OFFSET(BP_init_size, boot_params, hdr.init_size); > OFFSET(BP_pref_address, boot_params, hdr.pref_address); > OFFSET(BP_code32_start, boot_params, hdr.code32_start); > + OFFSET(BP_cmd_line_ptr, boot_params, hdr.cmd_line_ptr); > + OFFSET(BP_ext_cmd_line_ptr, boot_params, ext_cmd_line_ptr); > > BLANK(); > DEFINE(PTREGS_SIZE, sizeof(struct pt_regs)); > diff --git a/arch/x86/kernel/mem_encrypt.S b/arch/x86/kernel/mem_encrypt.S > index f2e0536..bf9f6a9 100644 > --- a/arch/x86/kernel/mem_encrypt.S > +++ b/arch/x86/kernel/mem_encrypt.S > @@ -12,13 +12,230 @@ > > #include <linux/linkage.h> > > +#include <asm/processor-flags.h> > +#include <asm/pgtable.h> > +#include <asm/page.h> > +#include <asm/msr.h> > +#include <asm/asm-offsets.h> > + > .text > .code64 > ENTRY(sme_enable) > +#ifdef CONFIG_AMD_MEM_ENCRYPT > + /* Check for AMD processor */ > + xorl %eax, %eax > + cpuid > + cmpl $0x68747541, %ebx # AuthenticAMD > + jne .Lmem_encrypt_exit > + cmpl $0x69746e65, %edx > + jne .Lmem_encrypt_exit > + cmpl $0x444d4163, %ecx > + jne .Lmem_encrypt_exit > + > + /* Check for memory encryption leaf */ > + movl $0x80000000, %eax > + cpuid > + cmpl $0x8000001f, %eax > + jb .Lmem_encrypt_exit > + > + /* > + * Check for memory encryption feature: > + * CPUID Fn8000_001F[EAX] - Bit 0 > + * Secure Memory Encryption support > + * CPUID Fn8000_001F[EBX] - Bits 5:0 > + * Pagetable bit position used to indicate encryption > + * CPUID Fn8000_001F[EBX] - Bits 11:6 > + * Reduction in physical address space (in bits) when enabled > + */ > + movl $0x8000001f, %eax > + cpuid > + bt $0, %eax > + jnc .Lmem_encrypt_exit > + > + /* Check if BIOS/UEFI has allowed memory encryption */ > + movl $MSR_K8_SYSCFG, %ecx > + rdmsr > + bt $MSR_K8_SYSCFG_MEM_ENCRYPT_BIT, %eax > + jnc .Lmem_encrypt_exit Like other people suggested, it would be great if this were in C. Should be actually readable :) > + > + /* Check for the mem_encrypt=on command line option */ > + push %rsi /* Save RSI (real_mode_data) */ > + push %rbx /* Save CPUID information */ > + movl BP_ext_cmd_line_ptr(%rsi), %ecx > + shlq $32, %rcx > + movl BP_cmd_line_ptr(%rsi), %edi > + addq %rcx, %rdi > + leaq mem_encrypt_enable_option(%rip), %rsi > + call cmdline_find_option_bool > + pop %rbx /* Restore CPUID information */ > + pop %rsi /* Restore RSI (real_mode_data) */ > + testl %eax, %eax > + jz .Lno_mem_encrypt This too. > + > + /* Set memory encryption mask */ > + movl %ebx, %ecx > + andl $0x3f, %ecx > + bts %ecx, sme_me_mask(%rip) > + > +.Lno_mem_encrypt: > + /* > + * BIOS/UEFI has allowed memory encryption so we need to set > + * the amount of physical address space reduction even if > + * the user decides not to use memory encryption. > + */ > + movl %ebx, %ecx > + shrl $6, %ecx > + andl $0x3f, %ecx > + movb %cl, sme_me_loss(%rip) > + > +.Lmem_encrypt_exit: > +#endif /* CONFIG_AMD_MEM_ENCRYPT */ > + > ret > ENDPROC(sme_enable) > > ENTRY(sme_encrypt_kernel) This should be doable too but I guess you'll have to try it to see. ... > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c > index 2f28d87..1154353 100644 > --- a/arch/x86/mm/mem_encrypt.c > +++ b/arch/x86/mm/mem_encrypt.c > @@ -183,6 +183,8 @@ void __init mem_encrypt_init(void) > > /* Make SWIOTLB use an unencrypted DMA area */ > swiotlb_clear_encryption(); > + > + pr_info("memory encryption active\n"); Let's make it more official with nice caps and so on... pr_info("AMD Secure Memory Encryption active.\n"); -- Regards/Gruss, Boris. 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