From: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx> Since KVM isn't equipped to handle closure of vcpu fd from userspace(QEMU) correctly, certain work arounds have to be employed to allow reuse of vcpu array slot in KVM during cpu hot plug/unplug from guest. One such proposed workaround is to park the vcpu fd in userspace during cpu unplug and reuse it later during next hotplug. More details can be found here: KVM: https://www.mail-archive.com/kvm@xxxxxxxxxxxxxxx/msg102839.html QEMU: http://lists.gnu.org/archive/html/qemu-devel/2014-12/msg00859.html In order to support this workaround with PowerPC KVM, don't create or initialize ICP if the vCPU is found to be already associated with an ICP. Signed-off-by: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxx> --- arch/powerpc/kvm/book3s_xics.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kvm/book3s_xics.c b/arch/powerpc/kvm/book3s_xics.c index a4a8d9f..ead3a35 100644 --- a/arch/powerpc/kvm/book3s_xics.c +++ b/arch/powerpc/kvm/book3s_xics.c @@ -1313,8 +1313,13 @@ int kvmppc_xics_connect_vcpu(struct kvm_device *dev, struct kvm_vcpu *vcpu, return -EPERM; if (xics->kvm != vcpu->kvm) return -EPERM; - if (vcpu->arch.irq_type) - return -EBUSY; + + /* + * If irq_type is already set, don't reinialize but + * return success allowing this vcpu to be reused. + */ + if (vcpu->arch.irq_type != KVMPPC_IRQ_DEFAULT) + return 0; r = kvmppc_xics_create_icp(vcpu, xcpu); if (!r) -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
