KVM: PPC: Enable compatibility mode

The host kernel implements a KVM_REG_PPC_ARCH_COMPAT register which
this uses to enable a compatibility mode if any chosen.

This sets the KVM_REG_PPC_ARCH_COMPAT register in KVM. ppc_set_compat()
signals the caller if the mode cannot be enabled by the host kernel.
Signed-off-by: NAlexey Kardashevskiy <aik@ozlabs.ru>
[agraf: fix TCG compat setting]
Signed-off-by: NAlexander Graf <agraf@suse.de>

target-ppc/kvm.c

@@ -1514,6 +1514,11 @@ void kvmppc_set_papr(PowerPCCPU *cpu)
     cap_papr = 1;
 }
 
+int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version)
+{
+    return kvm_set_one_reg(CPU(cpu), KVM_REG_PPC_ARCH_COMPAT, &cpu_version);
+}
+
 void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy)
 {
     CPUState *cs = CPU(cpu);

target-ppc/kvm_ppc.h

@@ -23,6 +23,7 @@ int kvmppc_get_hasidle(CPUPPCState *env);
 int kvmppc_get_hypercall(CPUPPCState *env, uint8_t *buf, int buf_len);
 int kvmppc_set_interrupt(PowerPCCPU *cpu, int irq, int level);
 void kvmppc_set_papr(PowerPCCPU *cpu);
+int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version);
 void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy);
 int kvmppc_smt_threads(void);
 int kvmppc_clear_tsr_bits(PowerPCCPU *cpu, uint32_t tsr_bits);
@@ -95,6 +96,11 @@ static inline void kvmppc_set_papr(PowerPCCPU *cpu)
 {
 }
 
+static inline int kvmppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version)
+{
+    return 0;
+}
+
 static inline void kvmppc_set_mpic_proxy(PowerPCCPU *cpu, int mpic_proxy)
 {
 }

target-ppc/translate_init.c

@@ -8970,6 +8970,11 @@ int ppc_set_compat(PowerPCCPU *cpu, uint32_t cpu_version)
         break;
     }
 
+    if (kvm_enabled() && kvmppc_set_compat(cpu, cpu->max_compat) < 0) {
+        error_report("Unable to set compatibility mode in KVM");
+        ret = -1;
+    }
+
     return ret;
 }