KVM: s390: infrastructure to kick vcpus out of guest state

To ensure vcpu's come out of guest context in certain cases this patch adds a
s390 specific way to kick them out of guest context. Currently it kicks them
out to rerun the vcpu_run path in the s390 code, but the mechanism itself is
expandable and with a new flag we could also add e.g. kicks to userspace etc.

Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>

5 files changed, 54 insertions, 27 deletions

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 1cd02f6073a0..0a784f6f9c90 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -182,8 +182,9 @@ struct kvm_s390_interrupt_info {
 };
 
 /* for local_interrupt.action_flags */
-#define ACTION_STORE_ON_STOP 1
-#define ACTION_STOP_ON_STOP  2
+#define ACTION_STORE_ON_STOP            (1<<0)
+#define ACTION_STOP_ON_STOP             (1<<1)
+#define ACTION_RELOADVCPU_ON_STOP       (1<<2)
 
 struct kvm_s390_local_interrupt {
         spinlock_t lock;
diff --git a/arch/s390/kvm/intercept.c b/arch/s390/kvm/intercept.c
index 98997ccba501..0732ab4305f4 100644
--- a/arch/s390/kvm/intercept.c
+++ b/arch/s390/kvm/intercept.c
@@ -128,7 +128,7 @@ static int handle_noop(struct kvm_vcpu *vcpu)
 
 static int handle_stop(struct kvm_vcpu *vcpu)
 {
-        int rc;
+        int rc = 0;
 
         vcpu->stat.exit_stop_request++;
         atomic_clear_mask(CPUSTAT_RUNNING, &vcpu->arch.sie_block->cpuflags);
@@ -141,12 +141,18 @@ static int handle_stop(struct kvm_vcpu *vcpu)
                         rc = -ENOTSUPP;
         }
 
+        if (vcpu->arch.local_int.action_bits & ACTION_RELOADVCPU_ON_STOP) {
+                vcpu->arch.local_int.action_bits &= ~ACTION_RELOADVCPU_ON_STOP;
+                rc = SIE_INTERCEPT_RERUNVCPU;
+                vcpu->run->exit_reason = KVM_EXIT_INTR;
+        }
+
         if (vcpu->arch.local_int.action_bits & ACTION_STOP_ON_STOP) {
                 vcpu->arch.local_int.action_bits &= ~ACTION_STOP_ON_STOP;
                 VCPU_EVENT(vcpu, 3, "%s", "cpu stopped");
                 rc = -ENOTSUPP;
-        } else
-                rc = 0;
+        }
+
         spin_unlock_bh(&vcpu->arch.local_int.lock);
         return rc;
 }
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 90d9d1ba258b..1d65f6277166 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -490,6 +490,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
 
         vcpu_load(vcpu);
 
+rerun_vcpu:
         /* verify, that memory has been registered */
         if (!vcpu->kvm->arch.guest_memsize) {
                 vcpu_put(vcpu);
@@ -509,6 +510,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                 vcpu->arch.sie_block->gpsw.addr = kvm_run->s390_sieic.addr;
                 break;
         case KVM_EXIT_UNKNOWN:
+        case KVM_EXIT_INTR:
         case KVM_EXIT_S390_RESET:
                 break;
         default:
@@ -522,6 +524,9 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                 rc = kvm_handle_sie_intercept(vcpu);
         } while (!signal_pending(current) && !rc);
 
+        if (rc == SIE_INTERCEPT_RERUNVCPU)
+                goto rerun_vcpu;
+
         if (signal_pending(current) && !rc)
                 rc = -EINTR;
 
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 748fee872323..2072cd4a013e 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -20,6 +20,8 @@
 
 typedef int (*intercept_handler_t)(struct kvm_vcpu *vcpu);
 
+/* negativ values are error codes, positive values for internal conditions */
+#define SIE_INTERCEPT_RERUNVCPU         (1<<0)
 int kvm_handle_sie_intercept(struct kvm_vcpu *vcpu);
 
 #define VM_EVENT(d_kvm, d_loglevel, d_string, d_args...)\
@@ -50,6 +52,7 @@ int kvm_s390_inject_vm(struct kvm *kvm,
 int kvm_s390_inject_vcpu(struct kvm_vcpu *vcpu,
                 struct kvm_s390_interrupt *s390int);
 int kvm_s390_inject_program_int(struct kvm_vcpu *vcpu, u16 code);
+int kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action);
 
 /* implemented in priv.c */
 int kvm_s390_handle_b2(struct kvm_vcpu *vcpu);
diff --git a/arch/s390/kvm/sigp.c b/arch/s390/kvm/sigp.c
index 0ef81d6776e9..21897b0f8a36 100644
--- a/arch/s390/kvm/sigp.c
+++ b/arch/s390/kvm/sigp.c
@@ -1,7 +1,7 @@
 /*
  * sigp.c - handlinge interprocessor communication
  *
- * Copyright IBM Corp. 2008
+ * Copyright IBM Corp. 2008,2009
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License (version 2 only)
@@ -9,6 +9,7 @@
  *
  *    Author(s): Carsten Otte <cotte@de.ibm.com>
  *               Christian Borntraeger <borntraeger@de.ibm.com>
+ *               Christian Ehrhardt <ehrhardt@de.ibm.com>
  */
 
 #include <linux/kvm.h>
@@ -107,46 +108,57 @@ unlock:
         return rc;
 }
 
-static int __sigp_stop(struct kvm_vcpu *vcpu, u16 cpu_addr, int store)
+static int __inject_sigp_stop(struct kvm_s390_local_interrupt *li, int action)
 {
-        struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
-        struct kvm_s390_local_interrupt *li;
         struct kvm_s390_interrupt_info *inti;
-        int rc;
-
-        if (cpu_addr >= KVM_MAX_VCPUS)
-                return 3; /* not operational */
 
         inti = kzalloc(sizeof(*inti), GFP_KERNEL);
         if (!inti)
                 return -ENOMEM;
-
         inti->type = KVM_S390_SIGP_STOP;
 
-        spin_lock(&fi->lock);
-        li = fi->local_int[cpu_addr];
-        if (li == NULL) {
-                rc = 3; /* not operational */
-                kfree(inti);
-                goto unlock;
-        }
         spin_lock_bh(&li->lock);
         list_add_tail(&inti->list, &li->list);
         atomic_set(&li->active, 1);
         atomic_set_mask(CPUSTAT_STOP_INT, li->cpuflags);
-        if (store)
-                li->action_bits |= ACTION_STORE_ON_STOP;
-        li->action_bits |= ACTION_STOP_ON_STOP;
+        li->action_bits |= action;
         if (waitqueue_active(&li->wq))
                 wake_up_interruptible(&li->wq);
         spin_unlock_bh(&li->lock);
-        rc = 0; /* order accepted */
+
+        return 0; /* order accepted */
+}
+
+static int __sigp_stop(struct kvm_vcpu *vcpu, u16 cpu_addr, int action)
+{
+        struct kvm_s390_float_interrupt *fi = &vcpu->kvm->arch.float_int;
+        struct kvm_s390_local_interrupt *li;
+        int rc;
+
+        if (cpu_addr >= KVM_MAX_VCPUS)
+                return 3; /* not operational */
+
+        spin_lock(&fi->lock);
+        li = fi->local_int[cpu_addr];
+        if (li == NULL) {
+                rc = 3; /* not operational */
+                goto unlock;
+        }
+
+        rc = __inject_sigp_stop(li, action);
+
 unlock:
         spin_unlock(&fi->lock);
         VCPU_EVENT(vcpu, 4, "sent sigp stop to cpu %x", cpu_addr);
         return rc;
 }
 
+int kvm_s390_inject_sigp_stop(struct kvm_vcpu *vcpu, int action)
+{
+        struct kvm_s390_local_interrupt *li = &vcpu->arch.local_int;
+        return __inject_sigp_stop(li, action);
+}
+
 static int __sigp_set_arch(struct kvm_vcpu *vcpu, u32 parameter)
 {
         int rc;
@@ -262,11 +274,11 @@ int kvm_s390_handle_sigp(struct kvm_vcpu *vcpu)
                 break;
         case SIGP_STOP:
                 vcpu->stat.instruction_sigp_stop++;
-                rc = __sigp_stop(vcpu, cpu_addr, 0);
+                rc = __sigp_stop(vcpu, cpu_addr, ACTION_STOP_ON_STOP);
                 break;
         case SIGP_STOP_STORE_STATUS:
                 vcpu->stat.instruction_sigp_stop++;
-                rc = __sigp_stop(vcpu, cpu_addr, 1);
+                rc = __sigp_stop(vcpu, cpu_addr, ACTION_STORE_ON_STOP);
                 break;
         case SIGP_SET_ARCH:
                 vcpu->stat.instruction_sigp_arch++;