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    Subject[PATCH v8 02/40] x86/sev: detect/setup SEV/SME features earlier in boot
    Date
    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>
    ---
    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
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