[MODERATED] Re: [PATCH 4/9] TAA 4

On Wed, Oct 23, 2019 at 11:30:45AM +0200, speck for Pawan Gupta wrote:
> diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
> index 885d4ac2111a..f8b8afc8f5b5 100644
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1128,6 +1128,21 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
>  	if (!cpu_matches(NO_SWAPGS))
>  		setup_force_cpu_bug(X86_BUG_SWAPGS);
>  
> +	/*
> +	 * When the CPU is not mitigated for TAA (TAA_NO=0) set TAA bug when:
> +	 *	- TSX is supported or
> +	 *	- TSX_CTRL is present
> +	 *
> +	 * TSX_CTRL check is needed for cases when TSX could be disabled before
> +	 * the kernel boot e.g. kexec.
> +	 * TSX_CTRL check alone is not sufficient for cases when the microcode
> +	 * update is not present or running as guest that don't get TSX_CTRL.
> +	 */
> +	if (!(ia32_cap & ARCH_CAP_TAA_NO) &&
> +	    (cpu_has(c, X86_FEATURE_RTM) ||
> +	     (ia32_cap & ARCH_CAP_TSX_CTRL_MSR)))
> +		setup_force_cpu_bug(X86_BUG_TAA);
> +

As I said before this would be a lot nicer if we could just add NO_TAA
to the cpu_vuln_whitelist.

-- 
Josh