KVM: PPC: Add generic single register ioctls

Right now we transfer a static struct every time we want to get or set
registers. Unfortunately, over time we realize that there are more of
these than we thought of before and the extensibility and flexibility of
transferring a full struct every time is limited.

So this is a new approach to the problem. With these new ioctls, we can
get and set a single register that is identified by an ID. This allows for
very precise and limited transmittal of data. When we later realize that
it's a better idea to shove over multiple registers at once, we can reuse
most of the infrastructure and simply implement a GET_MANY_REGS / SET_MANY_REGS
interface.

Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

1 files changed, 41 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index f4380cb264e0..089c61bf0e16 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -217,6 +217,7 @@ int kvm_dev_ioctl_check_extension(long ext)
 	case KVM_CAP_PPC_UNSET_IRQ:
 	case KVM_CAP_PPC_IRQ_LEVEL:
 	case KVM_CAP_ENABLE_CAP:
+	case KVM_CAP_ONE_REG:
 		r = 1;
 		break;
 #ifndef CONFIG_KVM_BOOK3S_64_HV
@@ -645,6 +646,32 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
 	return r;
 }
 
+static int kvm_vcpu_ioctl_get_one_reg(struct kvm_vcpu *vcpu,
+				      struct kvm_one_reg *reg)
+{
+	int r = -EINVAL;
+
+	switch (reg->id) {
+	default:
+		break;
+	}
+
+	return r;
+}
+
+static int kvm_vcpu_ioctl_set_one_reg(struct kvm_vcpu *vcpu,
+				      struct kvm_one_reg *reg)
+{
+	int r = -EINVAL;
+
+	switch (reg->id) {
+	default:
+		break;
+	}
+
+	return r;
+}
+
 int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu,
                                     struct kvm_mp_state *mp_state)
 {
@@ -684,6 +711,20 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
 		break;
 	}
 
+	case KVM_SET_ONE_REG:
+	case KVM_GET_ONE_REG:
+	{
+		struct kvm_one_reg reg;
+		r = -EFAULT;
+		if (copy_from_user(&reg, argp, sizeof(reg)))
+			goto out;
+		if (ioctl == KVM_SET_ONE_REG)
+			r = kvm_vcpu_ioctl_set_one_reg(vcpu, &reg);
+		else
+			r = kvm_vcpu_ioctl_get_one_reg(vcpu, &reg);
+		break;
+	}
+
 #ifdef CONFIG_KVM_E500
 	case KVM_DIRTY_TLB: {
 		struct kvm_dirty_tlb dirty;