Messages in this thread | | | Date | Wed, 6 Oct 2021 07:25:59 -0700 | From | Josh Poimboeuf <> | Subject | Re: [PATCH v8 03/11] x86/cpufeatures: Add TDX Guest CPU feature |
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On Mon, Oct 04, 2021 at 07:51:57PM -0700, Kuppuswamy Sathyanarayanan wrote: > +/* > + * Allocate it in the data region to avoid zeroing it during > + * BSS initialization. It is mainly used in cc_platform_has() > + * call during early boot call. > + */ > +u64 __section(".data") is_tdx_guest = 0;
Actually this should be __ro_after_init, since it never changes after it's initialized. As a bonus you won't have to worry about it getting placed in BSS and the comment and initializer can go away.
> + > +static void __init is_tdx_guest_init(void) > +{ > + u32 eax, sig[3]; > + > + if (cpuid_eax(0) < TDX_CPUID_LEAF_ID) { > + is_tdx_guest = 0; > + return; > + } > + > + cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax, &sig[0], &sig[2], &sig[1]); > + > + is_tdx_guest = !memcmp("IntelTDX ", sig, 12); > +} > + > +void __init tdx_early_init(void) > +{ > + is_tdx_guest_init(); > + > + if (!is_tdx_guest) > + return; > + > + setup_force_cpu_cap(X86_FEATURE_TDX_GUEST);
setup_force_cpu_cap() sets a bit in 'cpu_caps_set' which is in BSS, which gets cleared later right? So this presumably doesn't fully work as expected. Maybe it can be set in init_intel(), based on 'is_tdx_guest'.
-- Josh
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