Re: [PATCH v4 6/7] x86/cpu: Support AMD Automatic IBRS

[Dave Hansen]

On 11/30/22 17:50, Kim Phillips wrote:
> @@ -1240,8 +1240,11 @@ static const struct {
>  	{ "retpoline,lfence",	SPECTRE_V2_CMD_RETPOLINE_LFENCE,  false },
>  	{ "retpoline,generic",	SPECTRE_V2_CMD_RETPOLINE_GENERIC, false },
>  	{ "eibrs",		SPECTRE_V2_CMD_EIBRS,		  false },
> +	{ "autoibrs",		SPECTRE_V2_CMD_EIBRS,		  false },
>  	{ "eibrs,lfence",	SPECTRE_V2_CMD_EIBRS_LFENCE,	  false },
> +	{ "autoibrs,lfence",	SPECTRE_V2_CMD_EIBRS_LFENCE,	  false },
>  	{ "eibrs,retpoline",	SPECTRE_V2_CMD_EIBRS_RETPOLINE,	  false },
> +	{ "autoibrs,retpoline",	SPECTRE_V2_CMD_EIBRS_RETPOLINE,	  false },
>  	{ "auto",		SPECTRE_V2_CMD_AUTO,		  false },
>  	{ "ibrs",		SPECTRE_V2_CMD_IBRS,              false },

I don't think we should expose "autoibrs" to end users like this.
"eibrs" means always-on IBRS.  Intel did it first, so gets to name it.
Those are the rules, and it's why we call it "x86_64" and not whatever
Intel's silly name for it was.

Also, expanding the strings:

> +	[SPECTRE_V2_EIBRS_RETPOLINE]		= "Mitigation: Enhanced / Automatic IBRS + Retpolines",

is fine, but adding new user-visible options that we have to document is
not.