6 files changed, 48 insertions, 54 deletions
diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index bb82a906e51e..81f1b974c06a 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -2453,6 +2453,11 @@ return ENOEXEC for that vcpu.
 Note that because some registers reflect machine topology, all vcpus
 should be created before this ioctl is invoked.
+Userspace can call this function multiple times for a given vcpu, including
+after the vcpu has been run. This will reset the vcpu to its initial
+state. All calls to this function after the initial call must use the same
+target and same set of feature flags, otherwise EINVAL will be returned.
 Possible features:
        - KVM_ARM_VCPU_POWER_OFF: Starts the CPU in a power-off state.
          Depends on KVM_CAP_ARM_PSCI.  If not set, the CPU will be powered on
diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
index 53036e21756b..254e0650e48b 100644
--- a/arch/arm/include/asm/kvm_host.h
+++ b/arch/arm/include/asm/kvm_host.h
@@ -150,8 +150,6 @@ struct kvm_vcpu_stat {
        u32 halt_wakeup;
 };
-int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
-                        const struct kvm_vcpu_init *init);
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
 int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c
index 24c9ca4076b2..4043769583e7 100644
--- a/arch/arm/kvm/arm.c
+++ b/arch/arm/kvm/arm.c
@@ -263,6 +263,7 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
 {
        /* Force users to call KVM_ARM_VCPU_INIT */
        vcpu->arch.target = -1;
+        bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
        /* Set up the timer */
        kvm_timer_vcpu_init(vcpu);
@@ -649,6 +650,48 @@ int kvm_vm_ioctl_irq_line(struct kvm *kvm, struct kvm_irq_level *irq_level,
        return -EINVAL;
 }
+static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
+                               const struct kvm_vcpu_init *init)
+{
+        unsigned int i;
+        int phys_target = kvm_target_cpu();
+        if (init->target != phys_target)
+                return -EINVAL;
+        /*
+         * Secondary and subsequent calls to KVM_ARM_VCPU_INIT must
+         * use the same target.
+         */
+        if (vcpu->arch.target != -1 && vcpu->arch.target != init->target)
+                return -EINVAL;
+        /* -ENOENT for unknown features, -EINVAL for invalid combinations. */
+        for (i = 0; i < sizeof(init->features) * 8; i++) {
+                bool set = (init->features[i / 32] & (1 << (i % 32)));
+                if (set && i >= KVM_VCPU_MAX_FEATURES)
+                        return -ENOENT;
+                /*
+                 * Secondary and subsequent calls to KVM_ARM_VCPU_INIT must
+                 * use the same feature set.
+                 */
+                if (vcpu->arch.target != -1 && i < KVM_VCPU_MAX_FEATURES &&
+                    test_bit(i, vcpu->arch.features) != set)
+                        return -EINVAL;
+                if (set)
+                        set_bit(i, vcpu->arch.features);
+        }
+        vcpu->arch.target = phys_target;
+        /* Now we know what it is, we can reset it. */
+        return kvm_reset_vcpu(vcpu);
+}
 static int kvm_arch_vcpu_ioctl_vcpu_init(struct kvm_vcpu *vcpu,
                                         struct kvm_vcpu_init *init)
 {
diff --git a/arch/arm/kvm/guest.c b/arch/arm/kvm/guest.c
index 8c97208b9b97..384bab67c462 100644
--- a/arch/arm/kvm/guest.c
+++ b/arch/arm/kvm/guest.c
@@ -273,31 +273,6 @@ int __attribute_const__ kvm_target_cpu(void)
        }
 }
-int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
-                        const struct kvm_vcpu_init *init)
-{
-        unsigned int i;
-        /* We can only cope with guest==host and only on A15/A7 (for now). */
-        if (init->target != kvm_target_cpu())
-                return -EINVAL;
-        vcpu->arch.target = init->target;
-        bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
-        /* -ENOENT for unknown features, -EINVAL for invalid combinations. */
-        for (i = 0; i < sizeof(init->features) * 8; i++) {
-                if (test_bit(i, (void *)init->features)) {
-                        if (i >= KVM_VCPU_MAX_FEATURES)
-                                return -ENOENT;
-                        set_bit(i, vcpu->arch.features);
-                }
-        }
-        /* Now we know what it is, we can reset it. */
-        return kvm_reset_vcpu(vcpu);
-}
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
 {
        int target = kvm_target_cpu();
diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 2012c4ba8d67..65c615294589 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -165,8 +165,6 @@ struct kvm_vcpu_stat {
        u32 halt_wakeup;
 };
-int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
-                        const struct kvm_vcpu_init *init);
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init);
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
 int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 84d5959ff874..9535bd555d1d 100644
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -296,31 +296,6 @@ int __attribute_const__ kvm_target_cpu(void)
        return -EINVAL;
 }
-int kvm_vcpu_set_target(struct kvm_vcpu *vcpu,
-                        const struct kvm_vcpu_init *init)
-{
-        unsigned int i;
-        int phys_target = kvm_target_cpu();
-        if (init->target != phys_target)
-                return -EINVAL;
-        vcpu->arch.target = phys_target;
-        bitmap_zero(vcpu->arch.features, KVM_VCPU_MAX_FEATURES);
-        /* -ENOENT for unknown features, -EINVAL for invalid combinations. */
-        for (i = 0; i < sizeof(init->features) * 8; i++) {
-                if (init->features[i / 32] & (1 << (i % 32))) {
-                        if (i >= KVM_VCPU_MAX_FEATURES)
-                                return -ENOENT;
-                        set_bit(i, vcpu->arch.features);
-                }
-        }
-        /* Now we know what it is, we can reset it. */
-        return kvm_reset_vcpu(vcpu);
-}
 int kvm_vcpu_preferred_target(struct kvm_vcpu_init *init)
 {
        int target = kvm_target_cpu();