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    SubjectRe: [RFC PATCH v2 07/20] x86: Provide general kernel support for memory encryption
    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/head64.c b/arch/x86/kernel/head64.c
    > index 54a2372..88c7bae 100644
    > --- a/arch/x86/kernel/head64.c
    > +++ b/arch/x86/kernel/head64.c
    > @@ -28,6 +28,7 @@
    > #include <asm/bootparam_utils.h>
    > #include <asm/microcode.h>
    > #include <asm/kasan.h>
    > +#include <asm/mem_encrypt.h>
    >
    > /*
    > * Manage page tables very early on.
    > @@ -42,7 +43,7 @@ static void __init reset_early_page_tables(void)
    > {
    > memset(early_level4_pgt, 0, sizeof(pgd_t)*(PTRS_PER_PGD-1));
    > next_early_pgt = 0;
    > - write_cr3(__pa_nodebug(early_level4_pgt));
    > + write_cr3(__sme_pa_nodebug(early_level4_pgt));
    > }
    >
    > /* Create a new PMD entry */
    > @@ -54,7 +55,7 @@ int __init early_make_pgtable(unsigned long address)
    > pmdval_t pmd, *pmd_p;
    >
    > /* Invalid address or early pgt is done ? */
    > - if (physaddr >= MAXMEM || read_cr3() != __pa_nodebug(early_level4_pgt))
    > + if (physaddr >= MAXMEM || read_cr3() != __sme_pa_nodebug(early_level4_pgt))
    > return -1;
    >
    > again:
    > @@ -157,6 +158,11 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
    >
    > clear_page(init_level4_pgt);
    >
    > + /* Update the early_pmd_flags with the memory encryption mask */
    > + early_pmd_flags |= _PAGE_ENC;
    > +
    > + sme_early_init();
    > +

    So maybe this comes later but you're setting _PAGE_ENC unconditionally
    *before* sme_early_init().

    I think you should set it in sme_early_init() and iff SME is enabled.

    --
    Regards/Gruss,
    Boris.

    ECO tip #101: Trim your mails when you reply.

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