Re: [PATCH v8 02/40] x86/sev: detect/setup SEV/SME features earlier in boot

Venu Busireddy
2021-12-13T22:37:34Z

On 2021-12-10 09:42:54 -0600, Brijesh Singh wrote:
> From: Michael Roth <michael.roth@amd.com>
>
> sme_enable() handles feature detection for both SEV and SME. Future
> patches will also use it for SEV-SNP feature detection/setup, which
> will need to be done immediately after the first #VC handler is set up.
> Move it now in preparation.
>
> Signed-off-by: Michael Roth <michael.roth@amd.com>
> Signed-off-by: Brijesh Singh <brijesh.singh@amd.com>

Reviewed-by: Venu Busireddy <venu.busireddy@oracle.com>

> ---
> arch/x86/kernel/head64.c | 3 ---
> arch/x86/kernel/head_64.S | 13 +++++++++++++
> 2 files changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index 3be9dd213dad..b01f64e8389b 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -192,9 +192,6 @@ unsigned long __head __startup_64(unsigned long physaddr,
> if (load_delta & ~PMD_PAGE_MASK)
> for (;;);
>
> - /* Activate Secure Memory Encryption (SME) if supported and enabled */
> - sme_enable(bp);
> -
> /* Include the SME encryption mask in the fixup value */
> load_delta += sme_get_me_mask();
>
> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
> index d8b3ebd2bb85..99de8fd461e8 100644
> --- a/arch/x86/kernel/head_64.S
> +++ b/arch/x86/kernel/head_64.S
> @@ -69,6 +69,19 @@ SYM_CODE_START_NOALIGN(startup_64)
> call startup_64_setup_env
> popq %rsi
>
> +#ifdef CONFIG_AMD_MEM_ENCRYPT
> + /*
> + * Activate SEV/SME memory encryption if supported/enabled. This needs to
> + * be done now, since this also includes setup of the SEV-SNP CPUID table,
> + * which needs to be done before any CPUID instructions are executed in
> + * subsequent code.
> + */
> + movq %rsi, %rdi
> + pushq %rsi
> + call sme_enable
> + popq %rsi
> +#endif
> +
> /* Now switch to __KERNEL_CS so IRET works reliably */
> pushq $__KERNEL_CS
> leaq .Lon_kernel_cs(%rip), %rax
> --
> 2.25.1
>