[libvirt] [PATCHv2.5 09/10] qemu: Implement memory device hotplug
Peter Krempa
pkrempa at redhat.com
Mon Mar 16 15:09:36 UTC 2015
On Fri, Mar 13, 2015 at 20:48:39 -0400, John Ferlan wrote:
>
>
> On 03/04/2015 11:25 AM, Peter Krempa wrote:
> > Add code to hot-add memory devices to running qemu instances.
> > ---
> > src/qemu/qemu_command.c | 4 +--
> > src/qemu/qemu_command.h | 15 +++++++++
> > src/qemu/qemu_driver.c | 5 ++-
> > src/qemu/qemu_hotplug.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++
> > src/qemu/qemu_hotplug.h | 3 ++
> > 5 files changed, 109 insertions(+), 3 deletions(-)
...
> > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> > index 6b10e96..b917d76 100644
> > --- a/src/qemu/qemu_driver.c
> > +++ b/src/qemu/qemu_driver.c
> > @@ -7095,8 +7095,11 @@ qemuDomainAttachDeviceLive(virDomainObjPtr vm,
> > dev->data.rng = NULL;
> > break;
> >
> > - /*TODO: implement later */
> > case VIR_DOMAIN_DEVICE_MEMORY:
> > + ret = qemuDomainAttachMemory(driver, vm,
> > + dev->data.memory);
>
> Shouldn't there be a :
>
> if (!ret)
>
> prior to the following line (like the other cases in the switch)
No as qemuDomainAttachMemory always consumes the memory device
definition. I'll add a comment in the next version to clarify that.
>
> > + dev->data.memory = NULL;
> > + break;
> >
> > case VIR_DOMAIN_DEVICE_NONE:
> > case VIR_DOMAIN_DEVICE_FS:
> > diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
> > index cb2270e..967b678 100644
> > --- a/src/qemu/qemu_hotplug.c
> > +++ b/src/qemu/qemu_hotplug.c
> > @@ -1672,6 +1672,91 @@ qemuDomainAttachRNGDevice(virQEMUDriverPtr driver,
> > }
> >
> >
> > +int
> > +qemuDomainAttachMemory(virQEMUDriverPtr driver,
> > + virDomainObjPtr vm,
> > + virDomainMemoryDefPtr mem)
> > +{
> > + qemuDomainObjPrivatePtr priv = vm->privateData;
> > + virQEMUDriverConfigPtr cfg = virQEMUDriverGetConfig(driver);
> > + char *devstr = NULL;
> > + char *objalias = NULL;
> > + const char *backendType;
> > + virJSONValuePtr props = NULL;
> > + int id;
> > + int ret = -1;
> > +
> > + if (virAsprintf(&mem->info.alias, "dimm%zu", vm->def->nmems) < 0)
> > + goto cleanup;
> > +
> > + if (virAsprintf(&objalias, "mem%s", mem->info.alias) < 0)
> > + goto cleanup;
> > +
> > + if (!(devstr = qemuBuildMemoryDeviceStr(mem, priv->qemuCaps)))
> > + goto cleanup;
> > +
> > + qemuDomainMemoryDeviceAlignSize(mem);
> > +
> > + if (qemuBuildMemoryBackendStr(mem->size, mem->pagesize,
> > + mem->targetNode, mem->sourceNodes, NULL,
> > + vm->def, priv->qemuCaps, cfg,
> > + &backendType, &props, true) < 0)
> > + goto cleanup;
> > +
> > + if (virDomainMemoryInsert(vm->def, mem) < 0) {
> > + virJSONValueFree(props);
> > + goto cleanup;
> > + }
> > +
> > + qemuDomainObjEnterMonitor(driver, vm);
> > + if (qemuMonitorAddObject(priv->mon, backendType, objalias, props) < 0)
>
> I see from the AddObject comments, props is consumed upon success, but
> if we hit the else of mon->json, then we don't free it which we should -
> not related to this particular code, but something that should be fixed...
I'll fixed that as a separate patch that will be part of the next
posting.
> > + goto removedef;
> > +
> > + if (qemuMonitorAddDevice(priv->mon, devstr) < 0) {
> > + virErrorPtr err = virSaveLastError();
> > + ignore_value(qemuMonitorDelObject(priv->mon, objalias));
> > + virSetError(err);
> > + virFreeError(err);
> > + goto removedef;
> > + }
> > +
> > + if (qemuDomainObjExitMonitor(driver, vm) < 0) {
> > + /* we shouldn't touch mem now, as the def might be freed */
> > + mem = NULL;
> > + goto cleanup;
> > + }
> > +
> > + /* mem is consumed by vm->def */
> > + mem = NULL;
>
> Since both the Exit error path and this path set mem = NULL, why not
> just set it before the Exit and comment that it'll either consumed by
> vm->def on success or might be freed on failure...
It's always consumed, either freed or added to the definition. In some
cases it's necessary to track it separately as the @vm was unlocked
during monitor access.
Peter
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