KVM: PPC: Implement hypervisor interface

To communicate with KVM directly we need to plumb some sort of interface
between the guest and KVM. Usually those interfaces use hypercalls.

This hypercall implementation is described in the last patch of the series
in a special documentation file. Please read that for further information.

This patch implements stubs to handle KVM PPC hypercalls on the host and
guest side alike.

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

1 files changed, 32 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index 22f6fa2982f2..a4cf4b47e232 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -42,6 +42,38 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *v)
 	       !!(v->arch.pending_exceptions);
 }
 
+int kvmppc_kvm_pv(struct kvm_vcpu *vcpu)
+{
+	int nr = kvmppc_get_gpr(vcpu, 11);
+	int r;
+	unsigned long __maybe_unused param1 = kvmppc_get_gpr(vcpu, 3);
+	unsigned long __maybe_unused param2 = kvmppc_get_gpr(vcpu, 4);
+	unsigned long __maybe_unused param3 = kvmppc_get_gpr(vcpu, 5);
+	unsigned long __maybe_unused param4 = kvmppc_get_gpr(vcpu, 6);
+	unsigned long r2 = 0;
+
+	if (!(vcpu->arch.shared->msr & MSR_SF)) {
+		/* 32 bit mode */
+		param1 &= 0xffffffff;
+		param2 &= 0xffffffff;
+		param3 &= 0xffffffff;
+		param4 &= 0xffffffff;
+	}
+
+	switch (nr) {
+	case HC_VENDOR_KVM | KVM_HC_FEATURES:
+		r = HC_EV_SUCCESS;
+
+		/* Second return value is in r4 */
+		kvmppc_set_gpr(vcpu, 4, r2);
+		break;
+	default:
+		r = HC_EV_UNIMPLEMENTED;
+		break;
+	}
+
+	return r;
+}
 
 int kvmppc_emulate_mmio(struct kvm_run *run, struct kvm_vcpu *vcpu)
 {