target-ppc: Add helper for KVM_PPC_RTAS_DEFINE_TOKEN

Recent PowerKVM allows the kernel to intercept some RTAS calls from the
guest directly.  This is used to implement the more efficient in-kernel
XICS for example.  qemu is still responsible for assigning the RTAS token
numbers however, and needs to tell the kernel which RTAS function name is
assigned to a given token value.  This patch adds a convenience wrapper for
the KVM_PPC_RTAS_DEFINE_TOKEN ioctl() which is used for this purpose.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
Acked-by: NDavid Gibson <david@gibson.dropbear.id.au>
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/kvm.c

@@ -1789,6 +1789,20 @@ static int kvm_ppc_register_host_cpu_type(void)
     return 0;
 }
 
+int kvmppc_define_rtas_kernel_token(uint32_t token, const char *function)
+{
+    struct kvm_rtas_token_args args = {
+        .token = token,
+    };
+
+    if (!kvm_check_extension(kvm_state, KVM_CAP_PPC_RTAS)) {
+        return -ENOENT;
+    }
+
+    strncpy(args.name, function, sizeof(args.name));
+
+    return kvm_vm_ioctl(kvm_state, KVM_PPC_RTAS_DEFINE_TOKEN, &args);
+}
 
 int kvmppc_get_htab_fd(bool write)
 {

target-ppc/kvm_ppc.h

@@ -38,6 +38,7 @@ uint64_t kvmppc_rma_size(uint64_t current_size, unsigned int hash_shift);
 #endif /* !CONFIG_USER_ONLY */
 int kvmppc_fixup_cpu(PowerPCCPU *cpu);
 bool kvmppc_has_cap_epr(void);
+int kvmppc_define_rtas_kernel_token(uint32_t token, const char *function);
 int kvmppc_get_htab_fd(bool write);
 int kvmppc_save_htab(QEMUFile *f, int fd, size_t bufsize, int64_t max_ns);
 int kvmppc_load_htab_chunk(QEMUFile *f, int fd, uint32_t index,
@@ -164,6 +165,12 @@ static inline bool kvmppc_has_cap_epr(void)
     return false;
 }
 
+static inline int kvmppc_define_rtas_kernel_token(uint32_t token,
+                                                  const char *function)
+{
+    return -1;
+}
+
 static inline int kvmppc_get_htab_fd(bool write)
 {
     return -1;