# Re: \[PATCH v28 04/32\] x86/cpufeatures: Introduce CPU setup and option parsing for CET

- From: Yu, Yu-cheng \<hidden\>
- Date: 2021-08-10 15:40:43 
- List: linux-mm
- Page: https://ratatoskr.run/linux-mm/2021/08/1473382
- Thread: https://ratatoskr.run/linux-doc/2021/07/1455208/t.md

```text
On 8/9/2021 9:06 AM, Borislav Petkov wrote:
> On Thu, Jul 22, 2021 at 01:51:51PM -0700, Yu-cheng Yu wrote:
>>   /*
>>    * Some CPU features depend on higher CPUID levels, which may not always
>>    * be available due to CPUID level capping or broken virtualization
>> @@ -1249,6 +1257,11 @@ static void __init cpu_parse_early_param(void)
>>   	if (cmdline_find_option_bool(boot_command_line, "noxsaves"))
>>   		setup_clear_cpu_cap(X86_FEATURE_XSAVES);
>>   
>> +	if (cmdline_find_option_bool(boot_command_line, "no_user_shstk"))
>> +		setup_clear_cpu_cap(X86_FEATURE_SHSTK);
>> +	if (cmdline_find_option_bool(boot_command_line, "no_user_ibt"))
>> +		setup_clear_cpu_cap(X86_FEATURE_IBT);
>
> Patch 1 says:
>
> "Disabling shadow stack also disables IBT."
>
> I don't see that here.
>

We have X86_FEATURE_IBT dependent on X86_FEATURE_SHSTK (patch #3).

```