Hi Amit, One comment below ... Amit Machhiwal <amachhiw@xxxxxxxxxxxxx> writes: > Currently, rebooting a pseries nested qemu-kvm guest (L2) results in > below error as L1 qemu sends PVR value 'arch_compat' == 0 via > ppc_set_compat ioctl. This triggers a condition failure in > kvmppc_set_arch_compat() resulting in an EINVAL. ... > > diff --git a/arch/powerpc/kvm/book3s_hv_nestedv2.c b/arch/powerpc/kvm/book3s_hv_nestedv2.c > index 5378eb40b162..6042bdc70230 100644 > --- a/arch/powerpc/kvm/book3s_hv_nestedv2.c > +++ b/arch/powerpc/kvm/book3s_hv_nestedv2.c > @@ -347,8 +348,26 @@ static int gs_msg_ops_vcpu_fill_info(struct kvmppc_gs_buff *gsb, > break; > } > case KVMPPC_GSID_LOGICAL_PVR: > - rc = kvmppc_gse_put_u32(gsb, iden, > - vcpu->arch.vcore->arch_compat); > + /* > + * Though 'arch_compat == 0' would mean the default > + * compatibility, arch_compat, being a Guest Wide > + * Element, cannot be filled with a value of 0 in GSB > + * as this would result into a kernel trap. > + * Hence, when `arch_compat == 0`, arch_compat should > + * default to L1's PVR. > + * > + * Rework this when PowerVM supports a value of 0 > + * for arch_compat for KVM API v2. > + */ Is there an actual plan that PowerVM will support this in future? If so, how will a future kernel know that it's running on a version of PowerVM that does support arch_compat == 0? Similarly how will we know when it's OK to drop support for this workaround? cheers
