Re: [RFC PATCH 3/4] KVM: x86/tdx: Do VMXON and TDX-Module initialization during tdx_init()

[Chao Gao <chao.gao@intel.com>]

>-static int __tdx_enable(void)
>+static __init int tdx_enable(void)
> {
>+	enum cpuhp_state state;
> 	int ret;
> 
>+	if (!cpu_feature_enabled(X86_FEATURE_XSAVE)) {
>+		pr_err("XSAVE is required for TDX\n");
>+		return -EINVAL;
>+	}
>+
>+	if (!cpu_feature_enabled(X86_FEATURE_MOVDIR64B)) {
>+		pr_err("MOVDIR64B is required for TDX\n");
>+		return -EINVAL;
>+	}
>+
>+	if (!cpu_feature_enabled(X86_FEATURE_SELFSNOOP)) {
>+		pr_err("Self-snoop is required for TDX\n");
>+		return -ENODEV;
>+	}
>+
>+	state = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "virt/tdx:online",
>+				  tdx_online_cpu, tdx_offline_cpu);
>+	if (state < 0)
>+		return state;
>+
> 	ret = init_tdx_module();

...

>@@ -1445,11 +1462,6 @@ void __init tdx_init(void)
> 		return;
> 	}
> 
>-#if defined(CONFIG_ACPI) && defined(CONFIG_SUSPEND)
>-	pr_info("Disable ACPI S3. Turn off TDX in the BIOS to use ACPI S3.\n");
>-	acpi_suspend_lowlevel = NULL;
>-#endif
>-
> 	/*
> 	 * Just use the first TDX KeyID as the 'global KeyID' and
> 	 * leave the rest for TDX guests.
>@@ -1458,22 +1470,30 @@ void __init tdx_init(void)
> 	tdx_guest_keyid_start = tdx_keyid_start + 1;
> 	tdx_nr_guest_keyids = nr_tdx_keyids - 1;
> 
>+	err = tdx_enable();
>+	if (err)
>+		goto err_enable;

IIRC, existing TDX modules require all CPUs to have completed per-CPU
initialization before TDMR/PAMT initialization.

But at this point, APs are not online, so tdx_enable() will fail here.