KVM: s390: interpretive execution of SIGP EXTERNAL CALL

If the sigp interpretation facility is installed, most SIGP EXTERNAL CALL
operations will be interpreted instead of intercepted. A partial execution
interception will occurr at the sending cpu only if the target cpu is in the
wait state ("W" bit in the cpuflags set). Instruction interception will only
happen in error cases (e.g. cpu addr invalid).

As a sending cpu might set the external call interrupt pending flags at the
target cpu at every point in time, we can't handle this kind of interrupt using
our kvm interrupt injection mechanism. The injection will be done automatically
by the SIE when preparing the start of the target cpu.

Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
CC: Thomas Huth <thuth@linux.vnet.ibm.com>
[Adopt external call injection to check for sigp interpretion]
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

arch/s390/include/asm/kvm_host.h

@@ -32,8 +32,10 @@
 #define KVM_NR_IRQCHIPS 1
 #define KVM_IRQCHIP_NUM_PINS 4096
 
+#define SIGP_CTRL_C	0x00800000
+
 struct sca_entry {
-	atomic_t scn;
+	atomic_t ctrl;
 	__u32	reserved;
 	__u64	sda;
 	__u64	reserved2[2];

arch/s390/kvm/intercept.c

@@ -272,6 +272,8 @@ static int handle_external_interrupt(struct kvm_vcpu *vcpu)
 		irq.type = KVM_S390_INT_CPU_TIMER;
 		break;
 	case EXT_IRQ_EXTERNAL_CALL:
+		if (kvm_s390_si_ext_call_pending(vcpu))
+			return 0;
 		irq.type = KVM_S390_INT_EXTERNAL_CALL;
 		irq.parm = vcpu->arch.sie_block->extcpuaddr;
 		break;
@@ -323,6 +325,8 @@ static int handle_partial_execution(struct kvm_vcpu *vcpu)
 {
 	if (vcpu->arch.sie_block->ipa == 0xb254)	/* MVPG */
 		return handle_mvpg_pei(vcpu);
+	if (vcpu->arch.sie_block->ipa >> 8 == 0xae)	/* SIGP */
+		return kvm_s390_handle_sigp_pei(vcpu);
 
 	return -EOPNOTSUPP;
 }

arch/s390/kvm/interrupt.c

@@ -148,9 +148,8 @@ static void __unset_cpu_idle(struct kvm_vcpu *vcpu)
 
 static void __reset_intercept_indicators(struct kvm_vcpu *vcpu)
 {
-	atomic_clear_mask(CPUSTAT_ECALL_PEND |
-		CPUSTAT_IO_INT | CPUSTAT_EXT_INT | CPUSTAT_STOP_INT,
-		&vcpu->arch.sie_block->cpuflags);
+	atomic_clear_mask(CPUSTAT_IO_INT | CPUSTAT_EXT_INT | CPUSTAT_STOP_INT,
+			  &vcpu->arch.sie_block->cpuflags);
 	vcpu->arch.sie_block->lctl = 0x0000;
 	vcpu->arch.sie_block->ictl &= ~(ICTL_LPSW | ICTL_STCTL | ICTL_PINT);
 
@@ -524,6 +523,20 @@ static void deliver_ckc_interrupt(struct kvm_vcpu *vcpu)
 	}
 }
 
+/* Check whether SIGP interpretation facility has an external call pending */
+int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu)
+{
+	atomic_t *sigp_ctrl = &vcpu->kvm->arch.sca->cpu[vcpu->vcpu_id].ctrl;
+
+	if (!psw_extint_disabled(vcpu) &&
+	    (vcpu->arch.sie_block->gcr[0] & 0x2000ul) &&
+	    (atomic_read(sigp_ctrl) & SIGP_CTRL_C) &&
+	    (atomic_read(&vcpu->arch.sie_block->cpuflags) & CPUSTAT_ECALL_PEND))
+		return 1;
+
+	return 0;
+}
+
 int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
 {
 	struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
@@ -554,6 +567,9 @@ int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu)
 	if (!rc && kvm_cpu_has_pending_timer(vcpu))
 		rc = 1;
 
+	if (!rc && kvm_s390_si_ext_call_pending(vcpu))
+		rc = 1;
+
 	return rc;
 }
 
@@ -610,7 +626,8 @@ no_timer:
 	while (list_empty(&vcpu->arch.local_int.list) &&
 		list_empty(&vcpu->arch.local_int.float_int->list) &&
 		(!vcpu->arch.local_int.timer_due) &&
-		!signal_pending(current)) {
+		!signal_pending(current) &&
+		!kvm_s390_si_ext_call_pending(vcpu)) {
 		set_current_state(TASK_INTERRUPTIBLE);
 		spin_unlock_bh(&vcpu->arch.local_int.lock);
 		spin_unlock(&vcpu->arch.local_int.float_int->lock);
@@ -667,6 +684,11 @@ void kvm_s390_clear_local_irqs(struct kvm_vcpu *vcpu)
 	}
 	atomic_set(&li->active, 0);
 	spin_unlock_bh(&li->lock);
+
+	/* clear pending external calls set by sigp interpretation facility */
+	atomic_clear_mask(CPUSTAT_ECALL_PEND, &vcpu->arch.sie_block->cpuflags);
+	atomic_clear_mask(SIGP_CTRL_C,
+			  &vcpu->kvm->arch.sca->cpu[vcpu->vcpu_id].ctrl);
 }
 
 void kvm_s390_deliver_pending_interrupts(struct kvm_vcpu *vcpu)

arch/s390/kvm/kvm-s390.c

@@ -633,7 +633,7 @@ int kvm_arch_vcpu_setup(struct kvm_vcpu *vcpu)
 		vcpu->arch.sie_block->ecb |= 0x10;
 
 	vcpu->arch.sie_block->ecb2  = 8;
-	vcpu->arch.sie_block->eca   = 0xC1002000U;
+	vcpu->arch.sie_block->eca   = 0xD1002000U;
 	if (sclp_has_siif())
 		vcpu->arch.sie_block->eca |= 1;
 	vcpu->arch.sie_block->fac   = (int) (long) vfacilities;

arch/s390/kvm/kvm-s390.h

@@ -154,6 +154,7 @@ int kvm_s390_handle_eb(struct kvm_vcpu *vcpu);
 
 /* implemented in sigp.c */
 int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu);
+int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu);
 
 /* implemented in kvm-s390.c */
 long kvm_arch_fault_in_page(struct kvm_vcpu *vcpu, gpa_t gpa, int writable);
@@ -214,6 +215,7 @@ static inline int kvm_s390_inject_prog_cond(struct kvm_vcpu *vcpu, int rc)
 int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu);
 int psw_extint_disabled(struct kvm_vcpu *vcpu);
 void kvm_s390_destroy_adapters(struct kvm *kvm);
+int kvm_s390_si_ext_call_pending(struct kvm_vcpu *vcpu);
 
 /* implemented in guestdbg.c */
 void kvm_s390_backup_guest_per_regs(struct kvm_vcpu *vcpu);

arch/s390/kvm/sigp.c

@@ -458,3 +458,38 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
 	kvm_s390_set_psw_cc(vcpu, rc);
 	return 0;
 }
+
+/*
+ * Handle SIGP partial execution interception.
+ *
+ * This interception will occur at the source cpu when a source cpu sends an
+ * external call to a target cpu and the target cpu has the WAIT bit set in
+ * its cpuflags. Interception will occurr after the interrupt indicator bits at
+ * the target cpu have been set. All error cases will lead to instruction
+ * interception, therefore nothing is to be checked or prepared.
+ */
+int kvm_s390_handle_sigp_pei(struct kvm_vcpu *vcpu)
+{
+	int r3 = vcpu->arch.sie_block->ipa & 0x000f;
+	u16 cpu_addr = vcpu->run->s.regs.gprs[r3];
+	struct kvm_vcpu *dest_vcpu;
+	u8 order_code = kvm_s390_get_base_disp_rs(vcpu);
+
+	trace_kvm_s390_handle_sigp_pei(vcpu, order_code, cpu_addr);
+
+	if (order_code == SIGP_EXTERNAL_CALL) {
+		dest_vcpu = kvm_get_vcpu(vcpu->kvm, cpu_addr);
+		BUG_ON(dest_vcpu == NULL);
+
+		spin_lock_bh(&dest_vcpu->arch.local_int.lock);
+		if (waitqueue_active(&dest_vcpu->wq))
+			wake_up_interruptible(&dest_vcpu->wq);
+		dest_vcpu->preempted = true;
+		spin_unlock_bh(&dest_vcpu->arch.local_int.lock);
+
+		kvm_s390_set_psw_cc(vcpu, SIGP_CC_ORDER_CODE_ACCEPTED);
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}

arch/s390/kvm/trace.h

@@ -239,6 +239,29 @@ TRACE_EVENT(kvm_s390_handle_sigp,
 			   __entry->cpu_addr, __entry->parameter)
 	);
 
+TRACE_EVENT(kvm_s390_handle_sigp_pei,
+	    TP_PROTO(VCPU_PROTO_COMMON, __u8 order_code, __u16 cpu_addr),
+	    TP_ARGS(VCPU_ARGS_COMMON, order_code, cpu_addr),
+
+	    TP_STRUCT__entry(
+		    VCPU_FIELD_COMMON
+		    __field(__u8, order_code)
+		    __field(__u16, cpu_addr)
+		    ),
+
+	    TP_fast_assign(
+		    VCPU_ASSIGN_COMMON
+		    __entry->order_code = order_code;
+		    __entry->cpu_addr = cpu_addr;
+		    ),
+
+	    VCPU_TP_PRINTK("handle sigp pei order %02x (%s), cpu address %04x",
+			   __entry->order_code,
+			   __print_symbolic(__entry->order_code,
+					    sigp_order_codes),
+			   __entry->cpu_addr)
+	);
+
 TRACE_EVENT(kvm_s390_handle_diag,
 	    TP_PROTO(VCPU_PROTO_COMMON, __u16 code),
 	    TP_ARGS(VCPU_ARGS_COMMON, code),