Re: [PATCH 14/29] x86/ibt: Add IBT feature, MSR and #CP handling

[Edgecombe, Rick P]

On Fri, 2022-02-18 at 17:49 +0100, Peter Zijlstra wrote:
> +static __always_inline void setup_cet(struct cpuinfo_x86 *c)
> +{
> +       u64 msr;
> +
> +       if (!IS_ENABLED(CONFIG_X86_IBT) ||
> +           !cpu_feature_enabled(X86_FEATURE_IBT))
> +               return;
> +
> +       cr4_set_bits(X86_CR4_CET);
> +
> +       rdmsrl(MSR_IA32_S_CET, msr);
> +       if (cpu_feature_enabled(X86_FEATURE_IBT))

It must be true because of the above check.

> +               msr |= CET_ENDBR_EN;
> +       wrmsrl(MSR_IA32_S_CET, msr);
> +
> +       if (!ibt_selftest()) {
> +               pr_err("IBT selftest: Failed!\n");
> +               setup_clear_cpu_cap(X86_FEATURE_IBT);
> +       }
> +}
> +