diff --git a/arch/s390/include/asm/lowcore.h b/arch/s390/include/asm/lowcore.h
index 47bde5a20a41..11213c8bfca5 100644
--- a/arch/s390/include/asm/lowcore.h
+++ b/arch/s390/include/asm/lowcore.h
@@ -124,7 +124,8 @@ struct lowcore {
 	/* Restart function and parameter. */
 	__u64	restart_fn;			/* 0x0370 */
 	__u64	restart_data;			/* 0x0378 */
-	__u64	restart_source;			/* 0x0380 */
+	__u32	restart_source;			/* 0x0380 */
+	__u32	restart_flags;			/* 0x0384 */
 
 	/* Address space pointer. */
 	__u64	kernel_asce;			/* 0x0388 */
diff --git a/arch/s390/include/asm/processor.h b/arch/s390/include/asm/processor.h
index ddc7858bbce4..879b8e3f609c 100644
--- a/arch/s390/include/asm/processor.h
+++ b/arch/s390/include/asm/processor.h
@@ -26,6 +26,8 @@
 #define _CIF_MCCK_GUEST		BIT(CIF_MCCK_GUEST)
 #define _CIF_DEDICATED_CPU	BIT(CIF_DEDICATED_CPU)
 
+#define RESTART_FLAG_CTLREGS	_AC(1 << 0, U)
+
 #ifndef __ASSEMBLY__
 
 #include <linux/cpumask.h>
diff --git a/arch/s390/kernel/asm-offsets.c b/arch/s390/kernel/asm-offsets.c
index 77ff2130cb04..dc53b0452ce2 100644
--- a/arch/s390/kernel/asm-offsets.c
+++ b/arch/s390/kernel/asm-offsets.c
@@ -116,6 +116,7 @@ int main(void)
 	OFFSET(__LC_RESTART_FN, lowcore, restart_fn);
 	OFFSET(__LC_RESTART_DATA, lowcore, restart_data);
 	OFFSET(__LC_RESTART_SOURCE, lowcore, restart_source);
+	OFFSET(__LC_RESTART_FLAGS, lowcore, restart_flags);
 	OFFSET(__LC_KERNEL_ASCE, lowcore, kernel_asce);
 	OFFSET(__LC_USER_ASCE, lowcore, user_asce);
 	OFFSET(__LC_LPP, lowcore, lpp);
diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S
index 5a2f70cbd3a9..b9716a7e326d 100644
--- a/arch/s390/kernel/entry.S
+++ b/arch/s390/kernel/entry.S
@@ -624,12 +624,15 @@ ENTRY(mcck_int_handler)
 4:	j	4b
 ENDPROC(mcck_int_handler)
 
-#
-# PSW restart interrupt handler
-#
 ENTRY(restart_int_handler)
 	ALTERNATIVE "", ".insn s,0xb2800000,_LPP_OFFSET", 40
 	stg	%r15,__LC_SAVE_AREA_RESTART
+	TSTMSK	__LC_RESTART_FLAGS,RESTART_FLAG_CTLREGS,4
+	jz	0f
+	la	%r15,4095
+	lctlg	%c0,%c15,__LC_CREGS_SAVE_AREA-4095(%r15)
+0:	larl	%r15,.Lstosm_tmp
+	stosm	0(%r15),0x04			# turn dat on, keep irqs off
 	lg	%r15,__LC_RESTART_STACK
 	xc	STACK_FRAME_OVERHEAD(__PT_SIZE,%r15),STACK_FRAME_OVERHEAD(%r15)
 	stmg	%r0,%r14,STACK_FRAME_OVERHEAD+__PT_R0(%r15)
@@ -638,7 +641,7 @@ ENTRY(restart_int_handler)
 	xc	0(STACK_FRAME_OVERHEAD,%r15),0(%r15)
 	lg	%r1,__LC_RESTART_FN		# load fn, parm & source cpu
 	lg	%r2,__LC_RESTART_DATA
-	lg	%r3,__LC_RESTART_SOURCE
+	lgf	%r3,__LC_RESTART_SOURCE
 	ltgr	%r3,%r3				# test source cpu address
 	jm	1f				# negative -> skip source stop
 0:	sigp	%r4,%r3,SIGP_SENSE		# sigp sense to source cpu
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 50e2c21e0ec9..911cd3912351 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -179,8 +179,6 @@ static inline int __diag308(unsigned long subcode, void *addr)
 
 int diag308(unsigned long subcode, void *addr)
 {
-	if (IS_ENABLED(CONFIG_KASAN))
-		__arch_local_irq_stosm(0x04); /* enable DAT */
 	diag_stat_inc(DIAG_STAT_X308);
 	return __diag308(subcode, addr);
 }
@@ -1843,7 +1841,6 @@ static struct kobj_attribute on_restart_attr = __ATTR_RW(on_restart);
 
 static void __do_restart(void *ignore)
 {
-	__arch_local_irq_stosm(0x04); /* enable DAT */
 	smp_send_stop();
 #ifdef CONFIG_CRASH_DUMP
 	crash_kexec(NULL);
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 1005a6935fbe..c1fbc979e0e8 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -263,7 +263,6 @@ static void __do_machine_kexec(void *data)
  */
 static void __machine_kexec(void *data)
 {
-	__arch_local_irq_stosm(0x04); /* enable DAT */
 	pfault_fini();
 	tracing_off();
 	debug_locks_off();
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index ff0f9e838916..ee23908f1b96 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -421,7 +421,7 @@ static void __init setup_lowcore_dat_off(void)
 	lc->restart_stack = (unsigned long) restart_stack;
 	lc->restart_fn = (unsigned long) do_restart;
 	lc->restart_data = 0;
-	lc->restart_source = -1UL;
+	lc->restart_source = -1U;
 
 	mcck_stack = (unsigned long)memblock_alloc(THREAD_SIZE, THREAD_SIZE);
 	if (!mcck_stack)
@@ -450,12 +450,19 @@ static void __init setup_lowcore_dat_off(void)
 
 static void __init setup_lowcore_dat_on(void)
 {
+	struct lowcore *lc = lowcore_ptr[0];
+
 	__ctl_clear_bit(0, 28);
 	S390_lowcore.external_new_psw.mask |= PSW_MASK_DAT;
 	S390_lowcore.svc_new_psw.mask |= PSW_MASK_DAT;
 	S390_lowcore.program_new_psw.mask |= PSW_MASK_DAT;
 	S390_lowcore.io_new_psw.mask |= PSW_MASK_DAT;
+	__ctl_store(S390_lowcore.cregs_save_area, 0, 15);
 	__ctl_set_bit(0, 28);
+	mem_assign_absolute(S390_lowcore.restart_flags, RESTART_FLAG_CTLREGS);
+	mem_assign_absolute(S390_lowcore.program_new_psw, lc->program_new_psw);
+	memcpy_absolute(&S390_lowcore.cregs_save_area, lc->cregs_save_area,
+			sizeof(S390_lowcore.cregs_save_area));
 }
 
 static struct resource code_resource = {
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 8984711f72ed..8e8ace899407 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -252,6 +252,7 @@ static void pcpu_prepare_secondary(struct pcpu *pcpu, int cpu)
 	cpumask_set_cpu(cpu, &init_mm.context.cpu_attach_mask);
 	cpumask_set_cpu(cpu, mm_cpumask(&init_mm));
 	lc->cpu_nr = cpu;
+	lc->restart_flags = RESTART_FLAG_CTLREGS;
 	lc->spinlock_lockval = arch_spin_lockval(cpu);
 	lc->spinlock_index = 0;
 	lc->percpu_offset = __per_cpu_offset[cpu];
@@ -297,7 +298,7 @@ static void pcpu_start_fn(struct pcpu *pcpu, void (*func)(void *), void *data)
 	lc->restart_stack = lc->nodat_stack;
 	lc->restart_fn = (unsigned long) func;
 	lc->restart_data = (unsigned long) data;
-	lc->restart_source = -1UL;
+	lc->restart_source = -1U;
 	pcpu_sigp_retry(pcpu, SIGP_RESTART, 0);
 }
 
@@ -311,12 +312,12 @@ static void __pcpu_delegate(pcpu_delegate_fn *func, void *data)
 	func(data);	/* should not return */
 }
 
-static void __no_sanitize_address pcpu_delegate(struct pcpu *pcpu,
-						pcpu_delegate_fn *func,
-						void *data, unsigned long stack)
+static void pcpu_delegate(struct pcpu *pcpu,
+			  pcpu_delegate_fn *func,
+			  void *data, unsigned long stack)
 {
 	struct lowcore *lc = lowcore_ptr[pcpu - pcpu_devices];
-	unsigned long source_cpu = stap();
+	unsigned int source_cpu = stap();
 
 	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
 	if (pcpu->address == source_cpu) {
@@ -569,6 +570,9 @@ static void smp_ctl_bit_callback(void *info)
 	__ctl_load(cregs, 0, 15);
 }
 
+static DEFINE_SPINLOCK(ctl_lock);
+static unsigned long ctlreg;
+
 /*
  * Set a bit in a control register of all cpus
  */
@@ -576,6 +580,11 @@ void smp_ctl_set_bit(int cr, int bit)
 {
 	struct ec_creg_mask_parms parms = { 1UL << bit, -1UL, cr };
 
+	spin_lock(&ctl_lock);
+	memcpy_absolute(&ctlreg, &S390_lowcore.cregs_save_area[cr], sizeof(ctlreg));
+	__set_bit(bit, &ctlreg);
+	memcpy_absolute(&S390_lowcore.cregs_save_area[cr], &ctlreg, sizeof(ctlreg));
+	spin_unlock(&ctl_lock);
 	on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 }
 EXPORT_SYMBOL(smp_ctl_set_bit);
@@ -587,6 +596,11 @@ void smp_ctl_clear_bit(int cr, int bit)
 {
 	struct ec_creg_mask_parms parms = { 0, ~(1UL << bit), cr };
 
+	spin_lock(&ctl_lock);
+	memcpy_absolute(&ctlreg, &S390_lowcore.cregs_save_area[cr], sizeof(ctlreg));
+	__clear_bit(bit, &ctlreg);
+	memcpy_absolute(&S390_lowcore.cregs_save_area[cr], &ctlreg, sizeof(ctlreg));
+	spin_unlock(&ctl_lock);
 	on_each_cpu(smp_ctl_bit_callback, &parms, 1);
 }
 EXPORT_SYMBOL(smp_ctl_clear_bit);
@@ -895,14 +909,13 @@ static void smp_init_secondary(void)
 /*
  *	Activate a secondary processor.
  */
-static void __no_sanitize_address smp_start_secondary(void *cpuvoid)
+static void smp_start_secondary(void *cpuvoid)
 {
 	S390_lowcore.restart_stack = (unsigned long) restart_stack;
 	S390_lowcore.restart_fn = (unsigned long) do_restart;
 	S390_lowcore.restart_data = 0;
-	S390_lowcore.restart_source = -1UL;
-	__ctl_load(S390_lowcore.cregs_save_area, 0, 15);
-	__load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT);
+	S390_lowcore.restart_source = -1U;
+	S390_lowcore.restart_flags = 0;
 	call_on_stack_noreturn(smp_init_secondary, S390_lowcore.kernel_stack);
 }
 
