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, 113 insertions, 1 deletions

diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
index e402999..556fd59 100644
--- a/arch/powerpc/include/asm/kvm_para.h
+++ b/arch/powerpc/include/asm/kvm_para.h
@@ -21,6 +21,7 @@
 #define __POWERPC_KVM_PARA_H__
 
 #include <linux/types.h>
+#include <linux/of.h>
 
 struct kvm_vcpu_arch_shared {
 	__u64 sprg0;
@@ -34,16 +35,127 @@ struct kvm_vcpu_arch_shared {
 	__u32 dsisr;
 };
 
+#define KVM_SC_MAGIC_R0		0x4b564d21 /* "KVM!" */
+#define HC_VENDOR_KVM		(42 << 16)
+#define HC_EV_SUCCESS		0
+#define HC_EV_UNIMPLEMENTED	12
+
 #ifdef __KERNEL__
 
+#ifdef CONFIG_KVM_GUEST
+
+static inline int kvm_para_available(void)
+{
+	struct device_node *hyper_node;
+
+	hyper_node = of_find_node_by_path("/hypervisor");
+	if (!hyper_node)
+		return 0;
+
+	if (!of_device_is_compatible(hyper_node, "linux,kvm"))
+		return 0;
+
+	return 1;
+}
+
+extern unsigned long kvm_hypercall(unsigned long *in,
+				   unsigned long *out,
+				   unsigned long nr);
+
+#else
+
 static inline int kvm_para_available(void)
 {
 	return 0;
 }
 
+static unsigned long kvm_hypercall(unsigned long *in,
+				   unsigned long *out,
+				   unsigned long nr)
+{
+	return HC_EV_UNIMPLEMENTED;
+}
+
+#endif
+
+static inline long kvm_hypercall0_1(unsigned int nr, unsigned long *r2)
+{
+	unsigned long in[8];
+	unsigned long out[8];
+	unsigned long r;
+
+	r = kvm_hypercall(in, out, nr | HC_VENDOR_KVM);
+	*r2 = out[0];
+
+	return r;
+}
+
+static inline long kvm_hypercall0(unsigned int nr)
+{
+	unsigned long in[8];
+	unsigned long out[8];
+
+	return kvm_hypercall(in, out, nr | HC_VENDOR_KVM);
+}
+
+static inline long kvm_hypercall1(unsigned int nr, unsigned long p1)
+{
+	unsigned long in[8];
+	unsigned long out[8];
+
+	in[0] = p1;
+	return kvm_hypercall(in, out, nr | HC_VENDOR_KVM);
+}
+
+static inline long kvm_hypercall2(unsigned int nr, unsigned long p1,
+				  unsigned long p2)
+{
+	unsigned long in[8];
+	unsigned long out[8];
+
+	in[0] = p1;
+	in[1] = p2;
+	return kvm_hypercall(in, out, nr | HC_VENDOR_KVM);
+}
+
+static inline long kvm_hypercall3(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3)
+{
+	unsigned long in[8];
+	unsigned long out[8];
+
+	in[0] = p1;
+	in[1] = p2;
+	in[2] = p3;
+	return kvm_hypercall(in, out, nr | HC_VENDOR_KVM);
+}
+
+static inline long kvm_hypercall4(unsigned int nr, unsigned long p1,
+				  unsigned long p2, unsigned long p3,
+				  unsigned long p4)
+{
+	unsigned long in[8];
+	unsigned long out[8];
+
+	in[0] = p1;
+	in[1] = p2;
+	in[2] = p3;
+	in[3] = p4;
+	return kvm_hypercall(in, out, nr | HC_VENDOR_KVM);
+}
+
+
 static inline unsigned int kvm_arch_para_features(void)
 {
-	return 0;
+	unsigned long r;
+
+	if (!kvm_para_available())
+		return 0;
+
+	if(kvm_hypercall0_1(KVM_HC_FEATURES, &r))
+		return 0;
+
+	return r;
 }
 
 #endif /* __KERNEL__ */