On Fri, Jun 16, 2017 at 01:56:39PM -0500, Tom Lendacky wrote:
> Add support to check if SME has been enabled and if memory encryption
> should be activated (checking of command line option based on the
> configuration of the default state). If memory encryption is to be
> activated, then the encryption mask is set and the kernel is encrypted
> "in place."
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> ---
> arch/x86/include/asm/mem_encrypt.h | 6 ++-
> arch/x86/kernel/head64.c | 4 +-
> arch/x86/mm/mem_encrypt.c | 86 +++++++++++++++++++++++++++++++++++-
> 3 files changed, 90 insertions(+), 6 deletions(-)
...
> +/*
> + * Some SME functions run very early causing issues with the stack-protector
> + * support. Provide a way to turn off this support on a per-function basis.
> + */
> +#define SME_NOSTACKP __attribute__((__optimize__("no-stack-protector")))
__nostackp
just like the others in include/linux/compiler-gcc.h.
> +
> +static char sme_cmdline_arg[] __initdata = "mem_encrypt";
> +static char sme_cmdline_on[] __initdata = "on";
> +static char sme_cmdline_off[] __initdata = "off";
>
> /*
> * Since SME related variables are set early in the boot process they must
> @@ -200,6 +215,8 @@ void __init mem_encrypt_init(void)
>
> /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
> swiotlb_update_mem_attributes();
> +
> + pr_info("AMD Secure Memory Encryption (SME) active\n");
> }
>
> void swiotlb_set_mem_attributes(void *vaddr, unsigned long size)
> @@ -527,8 +544,73 @@ void __init sme_encrypt_kernel(void)
> native_write_cr3(__native_read_cr3());
> }
>
> -void __init sme_enable(void)
> +void __init SME_NOSTACKP sme_enable(struct boot_params *bp)
> {
> + const char *cmdline_ptr, *cmdline_arg, *cmdline_on, *cmdline_off;
> + unsigned int eax, ebx, ecx, edx;
> + bool active_by_default;
> + unsigned long me_mask;
> + char buffer[16];
> + u64 msr;
> +
> + /* Check for the SME support leaf */
> + eax = 0x80000000;
> + ecx = 0;
> + native_cpuid(&eax, &ebx, &ecx, &edx);
> + if (eax < 0x8000001f)
> + return;
> +
> + /*
> + * Check for the SME 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
> + */
> + eax = 0x8000001f;
> + ecx = 0;
> + native_cpuid(&eax, &ebx, &ecx, &edx);
> + if (!(eax & 1))
> + return;
> +
> + me_mask = 1UL << (ebx & 0x3f);
> +
> + /* Check if SME is enabled */
> + msr = __rdmsr(MSR_K8_SYSCFG);
> + if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
> + return;
> +
> + /*
> + * Fixups have not been applied to phys_base yet and we're running
> + * identity mapped, so we must obtain the address to the SME command
> + * line argument data using rip-relative addressing.
> + */
> + asm ("lea sme_cmdline_arg(%%rip), %0"
> + : "=r" (cmdline_arg)
> + : "p" (sme_cmdline_arg));
> + asm ("lea sme_cmdline_on(%%rip), %0"
> + : "=r" (cmdline_on)
> + : "p" (sme_cmdline_on));
> + asm ("lea sme_cmdline_off(%%rip), %0"
> + : "=r" (cmdline_off)
> + : "p" (sme_cmdline_off));
> +
> + if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT))
> + active_by_default = true;
> + else
> + active_by_default = false;
> +
> + cmdline_ptr = (const char *)((u64)bp->hdr.cmd_line_ptr |
> + ((u64)bp->ext_cmd_line_ptr << 32));
> +
> + cmdline_find_option(cmdline_ptr, cmdline_arg, buffer, sizeof(buffer));
> +
> + if (strncmp(buffer, cmdline_on, sizeof(buffer)) == 0)
if (!strncmp(...
> + sme_me_mask = me_mask;
> + else if (strncmp(buffer, cmdline_off, sizeof(buffer)) == 0)
else if (!strncmp(...
--
Regards/Gruss,
Boris.
Good mailing practices for 400: avoid top-posting and trim the reply.
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