[Qemu-ppc] [PATCH] ppc/kvm: use kvm_vm_check_extension() in kvmppc_is_pr()

[Greg Kurz]

If the host has both KVM PR and KVM HV loaded and we pass:

        -machine pseries,accel=kvm,kvm-type=PR

the kvmppc_is_pr() returns false instead of true. Since the helper
is mostly used as fallback, it doesn't have any real impact with
recent kernels. A notable exception is the workaround to allow
migration between compatible hosts with different PVRs (eg, POWER8
and POWER8E), since KVM still doesn't provide a way to check if a
specific PVR is supported (see commit c363a37a450f for details).

According to the official KVM API documentation [1], KVM_PPC_GET_PVINFO
is "vm ioctl", but we check it as a global ioctl. The following function
in KVM is hence called with kvm == NULL and considers we're in HV mode.

int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
{
        int r;
        /* Assume we're using HV mode when the HV module is loaded */
        int hv_enabled = kvmppc_hv_ops ? 1 : 0;

        if (kvm) {
                /*
                 * Hooray - we know which VM type we're running on. Depend on
                 * that rather than the guess above.
                 */
                hv_enabled = is_kvmppc_hv_enabled(kvm);
        }

Let's use kvm_vm_check_extension() to fix the issue.

[1] https://www.kernel.org/doc/Documentation/virtual/kvm/api.txt

Signed-off-by: Greg Kurz <address@hidden>
---
 target/ppc/kvm.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 6442dfcb95b3..1deaf106d2b9 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -120,7 +120,7 @@ static void kvm_kick_cpu(void *opaque)
 static bool kvmppc_is_pr(KVMState *ks)
 {
     /* Assume KVM-PR if the GET_PVINFO capability is available */
-    return kvm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
+    return kvm_vm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
 }
 
 static int kvm_ppc_register_host_cpu_type(void);