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 <jan.kiszka@siemens.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: jailhouse-dev@googlegroups.com
Link: https://lkml.kernel.org/r/44376558129d70a2c1527959811371ef4b82e829.1511770314.git.jan.kiszka@siemens.com

arch/x86/include/asm/x86_init.h

@@ -212,6 +212,7 @@ enum x86_legacy_i8042_state {
 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

@@ -316,6 +316,7 @@ static int __init uv_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
 	} 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

@@ -9,6 +9,7 @@ void __init x86_early_init_platform_quirks(void)
 {
 	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

@@ -934,7 +934,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle,
 	 * 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");
 
@@ -1006,7 +1006,7 @@ static int do_boot_cpu(int apicid, int cpu, struct task_struct *idle,
 	/* 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...
 		 */