x86/platform: Control warm reset setup via legacy feature flag

Allow to turn off the setup of BIOS-managed warm reset via a new flag in
x86_legacy_features. Besides the UV1, the upcoming jailhose guest support
needs this switched off.

Signed-off-by: Jan Kiszka <[e-mail]>
Signed-off-by: Thomas Gleixner <[e-mail]>
Cc: [e-mail]
Link: https://lkml.kernel.org/r/44[e-mail]

arch/x86/include/asm/x86_init.h

···
 struct x86_legacy_features {
 	enum x86_legacy_i8042_state i8042;
 	int rtc;
+	int warm_reset;
 	int no_vga;
 	int reserve_bios_regions;
 	struct x86_legacy_devices devices;

arch/x86/kernel/apic/x2apic_uv_x.c

···
 	} else if (!strcmp(oem_table_id, "UVH")) {
 		/* Only UV1 systems: */
 		uv_system_type = UV_NON_UNIQUE_APIC;
+		x86_platform.legacy.warm_reset = 0;
 		__this_cpu_write(x2apic_extra_bits, pnodeid << uvh_apicid.s.pnode_shift);
 		uv_set_apicid_hibit();
 		uv_apic = 1;

arch/x86/kernel/platform-quirks.c

···
 {
 	x86_platform.legacy.i8042 = X86_LEGACY_I8042_EXPECTED_PRESENT;
 	x86_platform.legacy.rtc = 1;
+	x86_platform.legacy.warm_reset = 1;
 	x86_platform.legacy.reserve_bios_regions = 0;
 	x86_platform.legacy.devices.pnpbios = 1;
 

arch/x86/kernel/smpboot.c

···
 	 * the targeted processor.
 	 */
 
-	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
+	if (x86_platform.legacy.warm_reset) {
 
 		pr_debug("Setting warm reset code and vector.\n");
 
···
 	/* mark "stuck" area as not stuck */
 	*trampoline_status = 0;
 
-	if (get_uv_system_type() != UV_NON_UNIQUE_APIC) {
+	if (x86_platform.legacy.warm_reset) {
 		/*
 		 * Cleanup possible dangling ends...
 		 */