KVM: s390: interrupt: fix virtual-physical confusion for next alert GISA

We sometimes put a virtual address in next_alert, which should always be
a physical address, since it is shared with hardware.

This currently works, because virtual and physical addresses are
the same.

Add phys_to_virt() to resolve the virtual-physical confusion.
Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Reviewed-by: Michael Mueller <mimu@linux.ibm.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
Link: https://lore.kernel.org/r/20230223162236.51569-1-nrb@linux.ibm.com
Message-Id: <20230223162236.51569-1-nrb@linux.ibm.com>

arch/s390/kvm/interrupt.c

@@ -305,7 +305,7 @@ static inline u8 gisa_get_ipm_or_restore_iam(struct kvm_s390_gisa_interrupt *gi)
 
 static inline int gisa_in_alert_list(struct kvm_s390_gisa *gisa)
 {
-	return READ_ONCE(gisa->next_alert) != (u32)(u64)gisa;
+	return READ_ONCE(gisa->next_alert) != (u32)virt_to_phys(gisa);
 }
 
 static inline void gisa_set_ipm_gisc(struct kvm_s390_gisa *gisa, u32 gisc)
@@ -3168,7 +3168,7 @@ void kvm_s390_gisa_init(struct kvm *kvm)
 	hrtimer_init(&gi->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
 	gi->timer.function = gisa_vcpu_kicker;
 	memset(gi->origin, 0, sizeof(struct kvm_s390_gisa));
-	gi->origin->next_alert = (u32)(u64)gi->origin;
+	gi->origin->next_alert = (u32)virt_to_phys(gi->origin);
 	VM_EVENT(kvm, 3, "gisa 0x%pK initialized", gi->origin);
 }