lkml.org 
[lkml]   [2021]   [Oct]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v8 03/11] x86/cpufeatures: Add TDX Guest CPU feature
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

\
 
 \ /
  Last update: 2021-10-06 16:26    [W:0.052 / U:0.192 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site