KVM: s390: abstract access to the VCPU cpu timer

We want to manually step the cpu timer in certain scenarios in the future.
Let's abstract any access to the cpu timer, so we can hide the complexity
internally.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/kvm/interrupt.c

@@ -182,8 +182,9 @@ static int cpu_timer_interrupts_enabled(struct kvm_vcpu *vcpu)
 
 static int cpu_timer_irq_pending(struct kvm_vcpu *vcpu)
 {
-	return (vcpu->arch.sie_block->cputm >> 63) &&
-	       cpu_timer_interrupts_enabled(vcpu);
+	if (!cpu_timer_interrupts_enabled(vcpu))
+		return 0;
+	return kvm_s390_get_cpu_timer(vcpu) >> 63;
 }
 
 static inline int is_ioirq(unsigned long irq_type)

arch/s390/kvm/kvm-s390.c

@@ -1429,6 +1429,18 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 	return 0;
 }
 
+/* set the cpu timer - may only be called from the VCPU thread itself */
+void kvm_s390_set_cpu_timer(struct kvm_vcpu *vcpu, __u64 cputm)
+{
+	vcpu->arch.sie_block->cputm = cputm;
+}
+
+/* get the cpu timer - can also be called from other VCPU threads */
+__u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu)
+{
+	return vcpu->arch.sie_block->cputm;
+}
+
 void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 {
 	/* Save host register state */
@@ -1476,7 +1488,7 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
 	vcpu->arch.sie_block->gpsw.mask = 0UL;
 	vcpu->arch.sie_block->gpsw.addr = 0UL;
 	kvm_s390_set_prefix(vcpu, 0);
-	vcpu->arch.sie_block->cputm     = 0UL;
+	kvm_s390_set_cpu_timer(vcpu, 0);
 	vcpu->arch.sie_block->ckc       = 0UL;
 	vcpu->arch.sie_block->todpr     = 0;
 	memset(vcpu->arch.sie_block->gcr, 0, 16 * sizeof(__u64));
@@ -1723,7 +1735,7 @@ static int kvm_arch_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
 			     (u64 __user *)reg->addr);
 		break;
 	case KVM_REG_S390_CPU_TIMER:
-		r = put_user(vcpu->arch.sie_block->cputm,
+		r = put_user(kvm_s390_get_cpu_timer(vcpu),
 			     (u64 __user *)reg->addr);
 		break;
 	case KVM_REG_S390_CLOCK_COMP:
@@ -1761,6 +1773,7 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
 					   struct kvm_one_reg *reg)
 {
 	int r = -EINVAL;
+	__u64 val;
 
 	switch (reg->id) {
 	case KVM_REG_S390_TODPR:
@@ -1772,8 +1785,9 @@ static int kvm_arch_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
 			     (u64 __user *)reg->addr);
 		break;
 	case KVM_REG_S390_CPU_TIMER:
-		r = get_user(vcpu->arch.sie_block->cputm,
-			     (u64 __user *)reg->addr);
+		r = get_user(val, (u64 __user *)reg->addr);
+		if (!r)
+			kvm_s390_set_cpu_timer(vcpu, val);
 		break;
 	case KVM_REG_S390_CLOCK_COMP:
 		r = get_user(vcpu->arch.sie_block->ckc,
@@ -2290,7 +2304,7 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 		kvm_make_request(KVM_REQ_TLB_FLUSH, vcpu);
 	}
 	if (kvm_run->kvm_dirty_regs & KVM_SYNC_ARCH0) {
-		vcpu->arch.sie_block->cputm = kvm_run->s.regs.cputm;
+		kvm_s390_set_cpu_timer(vcpu, kvm_run->s.regs.cputm);
 		vcpu->arch.sie_block->ckc = kvm_run->s.regs.ckc;
 		vcpu->arch.sie_block->todpr = kvm_run->s.regs.todpr;
 		vcpu->arch.sie_block->pp = kvm_run->s.regs.pp;
@@ -2312,7 +2326,7 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 	kvm_run->psw_addr = vcpu->arch.sie_block->gpsw.addr;
 	kvm_run->s.regs.prefix = kvm_s390_get_prefix(vcpu);
 	memcpy(&kvm_run->s.regs.crs, &vcpu->arch.sie_block->gcr, 128);
-	kvm_run->s.regs.cputm = vcpu->arch.sie_block->cputm;
+	kvm_run->s.regs.cputm = kvm_s390_get_cpu_timer(vcpu);
 	kvm_run->s.regs.ckc = vcpu->arch.sie_block->ckc;
 	kvm_run->s.regs.todpr = vcpu->arch.sie_block->todpr;
 	kvm_run->s.regs.pp = vcpu->arch.sie_block->pp;
@@ -2383,7 +2397,7 @@ int kvm_s390_store_status_unloaded(struct kvm_vcpu *vcpu, unsigned long gpa)
 	unsigned char archmode = 1;
 	freg_t fprs[NUM_FPRS];
 	unsigned int px;
-	u64 clkcomp;
+	u64 clkcomp, cputm;
 	int rc;
 
 	px = kvm_s390_get_prefix(vcpu);
@@ -2417,8 +2431,9 @@ int kvm_s390_store_status_unloaded(struct kvm_vcpu *vcpu, unsigned long gpa)
 			      &vcpu->run->s.regs.fpc, 4);
 	rc |= write_guest_abs(vcpu, gpa + __LC_TOD_PROGREG_SAVE_AREA,
 			      &vcpu->arch.sie_block->todpr, 4);
+	cputm = kvm_s390_get_cpu_timer(vcpu);
 	rc |= write_guest_abs(vcpu, gpa + __LC_CPU_TIMER_SAVE_AREA,
-			      &vcpu->arch.sie_block->cputm, 8);
+			      &cputm, 8);
 	clkcomp = vcpu->arch.sie_block->ckc >> 8;
 	rc |= write_guest_abs(vcpu, gpa + __LC_CLOCK_COMP_SAVE_AREA,
 			      &clkcomp, 8);

arch/s390/kvm/kvm-s390.h

@@ -263,6 +263,8 @@ int kvm_s390_vcpu_setup_cmma(struct kvm_vcpu *vcpu);
 void kvm_s390_vcpu_unsetup_cmma(struct kvm_vcpu *vcpu);
 unsigned long kvm_s390_fac_list_mask_size(void);
 extern unsigned long kvm_s390_fac_list_mask[];
+void kvm_s390_set_cpu_timer(struct kvm_vcpu *vcpu, __u64 cputm);
+__u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu);
 
 /* implemented in diag.c */
 int kvm_s390_handle_diag(struct kvm_vcpu *vcpu);