On Fri, 16 Nov 2018, Tim Chen wrote:
> +static const struct {
> + const char *option;
> + enum spectre_v2_app2app_mitigation_cmd cmd;
> + bool secure;
> +} app2app_options[] = {
> + { "off", SPECTRE_V2_APP2APP_CMD_NONE, false },
> + { "lite", SPECTRE_V2_APP2APP_CMD_LITE, false },
> + { "strict", SPECTRE_V2_APP2APP_CMD_STRICT, false },
> + { "auto", SPECTRE_V2_APP2APP_CMD_AUTO, false },
> + /*
> + * The "on" option is kept as last entry. It is implied by
> + * spectre_v2=on boot parameter and it is not checked
> + * in spectre_v2_app2app boot parameter.
> + */
> + { "on", SPECTRE_V2_APP2APP_CMD_FORCE, true },
FORCE is the same as STRICT. What's the point?
> @@ -376,6 +464,8 @@ static void __init spectre_v2_select_mitigation(void)
> {
> enum spectre_v2_mitigation_cmd cmd = spectre_v2_parse_cmdline();
> enum spectre_v2_mitigation mode = SPECTRE_V2_NONE;
> + enum spectre_v2_app2app_mitigation_cmd app2app_cmd;
> + enum spectre_v2_app2app_mitigation app2app_mode;
>
> /*
> * If the CPU is not affected and the command line mode is NONE or AUTO
> @@ -452,12 +542,6 @@ static void __init spectre_v2_select_mitigation(void)
> setup_force_cpu_cap(X86_FEATURE_RSB_CTXSW);
> pr_info("Spectre v2 / SpectreRSB mitigation: Filling RSB on context
> switch\n");
>
> - /* Initialize Indirect Branch Prediction Barrier if supported */
> - if (boot_cpu_has(X86_FEATURE_IBPB)) {
> - setup_force_cpu_cap(X86_FEATURE_USE_IBPB);
> - pr_info("Spectre v2 mitigation: Enabling Indirect Branch
> Prediction Barrier\n");
> - }
> -
> /*
> * Retpoline means the kernel is safe because it has no indirect
> * branches. Enhanced IBRS protects firmware too, so, enable restricted
> @@ -474,6 +558,43 @@ static void __init spectre_v2_select_mitigation(void)
> pr_info("Enabling Restricted Speculation for firmware calls\n");
> }
>
> + app2app_mode = SPECTRE_V2_APP2APP_NONE;
> + if (!boot_cpu_has(X86_FEATURE_IBPB) ||
> + !boot_cpu_has(X86_FEATURE_STIBP))
> + goto set_app2app_mode;
So before that change IBPB was usable without STIBP, now not longer. What's
the rationale?
This patch changes a gazillion things at once and is completely
unreviewable.
Thanks,
tglx
