On 14.09.2017 12:48, Greg Kurz wrote: > 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.
By the way, what about the other CAPs that rely on hv_enabled? grepping through the QEMU sources, I can see: cap_ppc_smt = kvm_check_extension(s, KVM_CAP_PPC_SMT); cap_htab_fd = kvm_check_extension(s, KVM_CAP_PPC_HTAB_FD); int ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS); return kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU); !kvm_check_extension(cs->kvm_state, KVM_CAP_SW_TLB)) { ... do we need to fix them, too? Thomas