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    SubjectRe: [RFC PATCH v2 07/20] x86: Provide general kernel support for memory encryption
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    On 09/05/2016 10:22 AM, Borislav Petkov wrote:
    > On Mon, Aug 22, 2016 at 05:36:46PM -0500, Tom Lendacky wrote:
    >> Adding general kernel support for memory encryption includes:
    >> - Modify and create some page table macros to include the Secure Memory
    >> Encryption (SME) memory encryption mask
    >> - Update kernel boot support to call an SME routine that checks for and
    >> sets the SME capability (the SME routine will grow later and for now
    >> is just a stub routine)
    >> - Update kernel boot support to call an SME routine that encrypts the
    >> kernel (the SME routine will grow later and for now is just a stub
    >> routine)
    >> - Provide an SME initialization routine to update the protection map with
    >> the memory encryption mask so that it is used by default
    >>
    >> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
    >
    > ...
    >
    >> diff --git a/arch/x86/kernel/head_64.S b/arch/x86/kernel/head_64.S
    >> index c98a559..30f7715 100644
    >> --- a/arch/x86/kernel/head_64.S
    >> +++ b/arch/x86/kernel/head_64.S
    >> @@ -95,6 +95,13 @@ startup_64:
    >> jnz bad_address
    >>
    >> /*
    >> + * Enable memory encryption (if available). Add the memory encryption
    >> + * mask to %rbp to include it in the the page table fixup.
    >> + */
    >> + call sme_enable
    >> + addq sme_me_mask(%rip), %rbp
    >> +
    >> + /*
    >> * Fixup the physical addresses in the page table
    >> */
    >> addq %rbp, early_level4_pgt + (L4_START_KERNEL*8)(%rip)
    >> @@ -116,7 +123,8 @@ startup_64:
    >> movq %rdi, %rax
    >> shrq $PGDIR_SHIFT, %rax
    >>
    >> - leaq (4096 + _KERNPG_TABLE)(%rbx), %rdx
    >> + leaq (4096 + __KERNPG_TABLE)(%rbx), %rdx
    >> + addq sme_me_mask(%rip), %rdx /* Apply mem encryption mask */
    >
    > Please add comments over the line and not at the side...

    Ok, will do.

    Thanks,
    Tom

    >

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