Re: [PATCH v3 6/7] x86/cpu, kvm: Support AMD Automatic IBRS

[Pawan Gupta]

On Tue, Nov 29, 2022 at 05:58:15PM -0600, Kim Phillips wrote:
> --- a/arch/x86/kernel/cpu/common.c
> +++ b/arch/x86/kernel/cpu/common.c
> @@ -1406,6 +1406,14 @@ static void __init cpu_set_bug_bits(struct cpuinfo_x86 *c)
> 	    !(ia32_cap & ARCH_CAP_PBRSB_NO))
> 		setup_force_cpu_bug(X86_BUG_EIBRS_PBRSB);
>
> +	/*
> +	 * AMD's AutoIBRS is equivalent to Intel's eIBRS - use the Intel flag only
> +	 * after IBRS_ENHANCED bugs such as BUG_EIBRS_PBRSB above have been
> +	 * determined.
> +	 */

Minor comment, setting NO_EIBRS_PBRSB in cpu_vuln_whitelist for
non-EIBRS CPUs also (AMD and others) can remove this order dependency.

> +	if (cpu_has(c, X86_FEATURE_AUTOIBRS))
> +		setup_force_cpu_cap(X86_FEATURE_IBRS_ENHANCED);