Re: [libvirt] [PATCHv2 01/16] qemu: Add KVM CPUs into cache only if KVM is present

On Wed, Nov 21, 2018 at 20:50:50 +0300, Roman Bolshakov wrote: > On Wed, Nov 21, 2018 at 05:04:07PM +0100, Jiri Denemark wrote: > > On Wed, Nov 21, 2018 at 17:01:44 +0300, Roman Bolshakov wrote: > > > diff --git a/src/qemu/qemu_capabilities.c b/src/qemu/qemu_capabilities.c > > > index fde27010e4..4ba8369e3a 100644 > > > --- a/src/qemu/qemu_capabilities.c > > > +++ b/src/qemu/qemu_capabilities.c > > > @@ -3467,11 +3467,13 @@ virQEMUCapsLoadCache(virArch hostArch, > > > } > > > VIR_FREE(str); > > > > > > - if (virQEMUCapsLoadHostCPUModelInfo(qemuCaps, ctxt, VIR_DOMAIN_VIRT_KVM) < 0 || > > > + if ((virQEMUCapsGet(qemuCaps, QEMU_CAPS_KVM) && > > > + virQEMUCapsLoadHostCPUModelInfo(qemuCaps, ctxt, VIR_DOMAIN_VIRT_KVM) < 0) || > > > virQEMUCapsLoadHostCPUModelInfo(qemuCaps, ctxt, VIR_DOMAIN_VIRT_QEMU) < 0) > > > goto cleanup; > > > > I don't think we should introduce these guards in all the places. All > > the loading and formatting functions should return success if the > > appropriate info is not available, so you should just make sure the > > relevant info is NULL in qemuCaps. > > Do you mean the capabilities checks should be moved inside the > functions? virQEMUCapsLoadHostCPUModelInfo does (not literally, but effectively) hostCPUNode = virXPathNode("./hostCPU[@type='kvm']", ctxt); if (!hostCPUNode) return 0; virQEMUCapsLoadCPUModels does n = virXPathNodeSet("./cpu[@type='kvm']", ctxt, &nodes); if (n == 0) return 0;

virQEMUCapsInitHostCPUModel always fills in something and your check should probably remain in place for it virQEMUCapsFormatHostCPUModelInfo does virQEMUCapsHostCPUDataPtr cpuData = &qemuCaps->kvmCPU; qemuMonitorCPUModelInfoPtr model = cpuData->info; if (!model) return; virQEMUCapsFormatCPUModels cpus = qemuCaps->kvmCPUModels; if (!cpus) return; So to me it looks like all functions are ready to see NULL pointers and just do nothing if that's the case. Thus the only thing this patch should need to do is to make sure virQEMUCapsInitHostCPUModel does not set something non-NULL there.