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    SubjectRe: [PATCH v9 04/38] x86/CPU/AMD: Add the Secure Memory Encryption CPU feature
    On Tue, Jul 11, 2017 at 01:07:46AM -0400, Brian Gerst wrote:
    > > If I make the scattered feature support conditional on CONFIG_X86_64
    > > (based on comment below) then cpu_has() will always be false unless
    > > CONFIG_X86_64 is enabled. So this won't need to be wrapped by the
    > > #ifdef.
    >
    > If you change it to use cpu_feature_enabled(), gcc will see that it is
    > disabled and eliminate the dead code at compile time.

    Just do this:

    if (cpu_has(c, X86_FEATURE_SME)) {
    if (IS_ENABLED(CONFIG_X86_32)) {
    clear_cpu_cap(c, X86_FEATURE_SME);
    } else {
    u64 msr;

    /* Check if SME is enabled */
    rdmsrl(MSR_K8_SYSCFG, msr);
    if (!(msr & MSR_K8_SYSCFG_MEM_ENCRYPT))
    clear_cpu_cap(c, X86_FEATURE_SME);
    }
    }

    so that it is explicit that we disable it on 32-bit and we can save us
    the ifdeffery elsewhere.

    Thanks.

    --
    Regards/Gruss,
    Boris.

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

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