linux-kernel - Re: [RFC][PATCH 11/17] x86/cpu: Remove all SRSO interface nonsense

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Message-ID: <20230809140530.bijq3asl26d2pu7u@treble>
Date:   Wed, 9 Aug 2023 10:05:30 -0400
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, David.Kaplan@....com,
        Andrew.Cooper3@...rix.com, gregkh@...uxfoundation.org
Subject: Re: [RFC][PATCH 11/17] x86/cpu: Remove all SRSO interface nonsense

On Wed, Aug 09, 2023 at 09:12:29AM +0200, Peter Zijlstra wrote:
> @@ -2607,26 +2447,26 @@ static ssize_t srbds_show_state(char *bu
>  static ssize_t retbleed_show_state(char *buf)
>  {
>  	if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET ||
> +	    retbleed_mitigation == RETBLEED_MITIGATION_UNRET_SRSO ||
> +	    retbleed_mitigation == RETBLEED_MITIGATION_UNRET_SRSO_ALIAS ||
>  	    retbleed_mitigation == RETBLEED_MITIGATION_IBPB) {

These retbleed_show_state() changes probably belong in that other patch
which adds the retbleed= cmdline options.

> +
>  		if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD &&
>  		    boot_cpu_data.x86_vendor != X86_VENDOR_HYGON)
>  			return sysfs_emit(buf, "Vulnerable: untrained return thunk / IBPB on non-AMD based uarch\n");
>  
> -		return sysfs_emit(buf, "%s; SMT %s\n", retbleed_strings[retbleed_mitigation],
> +		return sysfs_emit(buf, "%s; SMT %s%s\n", retbleed_strings[retbleed_mitigation],
>  				  !sched_smt_active() ? "disabled" :
>  				  spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||
>  				  spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT_PREFERRED ?
> -				  "enabled with STIBP protection" : "vulnerable");
> -	}
> +				  "enabled with STIBP protection" : "vulnerable",
> +				  cpu_has_ibpb_brtype_microcode() ? "" : ", no SRSO microcode");

Hm?  What does missing microcode have to do with SMT?

-- 
Josh