Messages in this thread | | | Date | Tue, 11 Jul 2017 07:56:59 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH v9 04/38] x86/CPU/AMD: Add the Secure Memory Encryption CPU feature |
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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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