Re: [PATCH v2] x86/fpu: Disable shstk if no CET_USER state

[Dave Hansen]

On 4/8/26 07:30, David Kaplan wrote:
> +	if (boot_cpu_has(X86_FEATURE_USER_SHSTK) &&
> +	    !(fpu_kernel_cfg.max_features & XFEATURE_MASK_CET_USER)) {
> +		/*
> +		 * The kernel relies on XSAVES/XRSTORS to context switch shadow
> +		 * stack state.  If this isn't present, disable user shadow
> +		 * stacks.
> +		 */
> +		pr_err("x86/fpu: CET_USER not supported in xstate when CET is supported.  Disabling shadow stacks.\n");
> +		setup_clear_cpu_cap(X86_FEATURE_USER_SHSTK);
> +	}

Are there any more of these? I'm wondering if we want a table that's
effectively the reverse of xsave_cpuid_features[].

Maybe X86_FEATURE_ENQCMD at least?