Hi Michal, I tried to test the virtio-mem with upstream version v7.7.0-136-g9b49c2c6d3 adding the current patch (with qemu-6.1.0-7.fc36.x86_64) - <maxMemory slots='16' unit='KiB'>8388608</maxMemory> <memory unit='KiB'>1179648</memory> <currentMemory unit='KiB'>1179648</currentMemory> <memoryBacking> <allocation mode='immediate'/> </memoryBacking> .... <cpu mode='custom' match='exact' check='none'> <model fallback='forbid'>qemu64</model> <numa> <cell id='0' cpus='0-1' memory='1048576' unit='KiB' discard='yes'/> </numa> </cpu> ... <memory model='virtio-mem'> <source> <nodemask>0</nodemask> <pagesize unit='KiB'>2048</pagesize> </source> <target> <size unit='KiB'>131072</size> <node>0</node> <block unit='KiB'>2048</block> <requested unit='KiB'>131072</requested> </target> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </memory> The vm was started successfully and there was no "prealloc: true" in the command line. But I also found when <allocation mode='immediate'/> was added in the domain and the "virtio-mem" device was not added, the qemu command line also didn't have "prealloc:true". Is this correct? This result is different in "libvirt-7.6.0-3.module+el8.5.0+12510+80564ecf.x86_64" & "qemu-kvm-6.0.0-29.module+el8.5.0+12386+43574bac.x86_64". Best Regards, Jing Qi On Tue, Sep 14, 2021 at 9:07 PM David Hildenbrand <david@redhat.com> wrote:
On 13.09.21 16:52, Michal Privoznik wrote:
Nothing special is happening here. All important changes were done when for 'virtio-pmem' (adjusting the code to put virtio memory on PCI bus, generating alias using qemuDomainDeviceAliasIndex(). The only bit that might look suspicious is no prealloc for virtio-mem. But if you think about it, the whole purpose of this device is to change amount of memory exposed to guest on the fly. There is no point in locking the whole backend in memory.
Do I understand correctly that we'll always try setting "reserve=off", and "prealloc=off"? That would be awesome :)
I do wonder if we want to warn or bail out if "priv->memPrealloc" is set but we are temporarily not able to support it -- as discussed, because virtio-mem in QEMU yet has to be taught about it.
FYI: QEMU will bail out if "reserve=off,prealloc=on" is set in combination.
Signed-off-by: Michal Privoznik <mprivozn@redhat.com> --- src/qemu/qemu_alias.c | 9 +++- src/qemu/qemu_command.c | 24 +++++++++-- ...mory-hotplug-virtio-mem.x86_64-latest.args | 41 +++++++++++++++++++ tests/qemuxml2argvtest.c | 1 + 4 files changed, 70 insertions(+), 5 deletions(-) create mode 100644
tests/qemuxml2argvdata/memory-hotplug-virtio-mem.x86_64-latest.args
diff --git a/src/qemu/qemu_alias.c b/src/qemu/qemu_alias.c index 79e8953b2f..81a1e7eeed 100644 --- a/src/qemu/qemu_alias.c +++ b/src/qemu/qemu_alias.c @@ -475,8 +475,11 @@ qemuDeviceMemoryGetAliasID(virDomainDef *def, size_t i; int maxidx = 0;
- /* virtio-pmem goes onto PCI bus and thus DIMM address is not valid
*/
- if (!oldAlias && mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM) + /* virtio-pmem and virtio-mem go onto PCI bus and thus DIMM address is not + * valid */ + if (!oldAlias && + mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_PMEM && + mem->model != VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM) return mem->info.addr.dimm.slot;
for (i = 0; i < def->nmems; i++) { @@ -523,6 +526,8 @@ qemuAssignDeviceMemoryAlias(virDomainDef *def, prefix = "virtiopmem"; break; case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM: + prefix = "virtiomem"; + break; case VIR_DOMAIN_MEMORY_MODEL_NONE: case VIR_DOMAIN_MEMORY_MODEL_LAST: default: diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 594e5643b1..91f3094ac8 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -3136,9 +3136,19 @@ qemuBuildMemoryBackendProps(virJSONValue **backendProps, virJSONValueObjectAdd(props, "b:x-use-canonical-path-for-ramblock-id", false, NULL) < 0) return -1;
- if (!priv->memPrealloc && - virJSONValueObjectAdd(props, "B:prealloc", prealloc, NULL) < 0) - return -1; + if (mem->model == VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM) { + /* Explicitly disable prealloc for virtio-mem */ + if (priv->memPrealloc && + virJSONValueObjectAppendBoolean(props, "prealloc", 0) < 0) + return -1; + if (virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_MEMORY_BACKEND_RESERVE) && + virJSONValueObjectAppendBoolean(props, "reserve", 0) < 0) + return -1; + } else { + if (!priv->memPrealloc && + virJSONValueObjectAdd(props, "B:prealloc", prealloc, NULL) < 0) + return -1; + }
if (virJSONValueObjectAdd(props, "U:size", mem->size * 1024, NULL) < 0) return -1; @@ -3318,6 +3328,9 @@ qemuBuildMemoryDeviceStr(const virDomainDef *def, break;
case VIR_DOMAIN_MEMORY_MODEL_VIRTIO_MEM: + device = "virtio-mem-pci"; + break; + case VIR_DOMAIN_MEMORY_MODEL_NONE: case VIR_DOMAIN_MEMORY_MODEL_LAST: default: @@ -3334,6 +3347,11 @@ qemuBuildMemoryDeviceStr(const virDomainDef *def, if (mem->labelsize) virBufferAsprintf(&buf, "label-size=%llu,", mem->labelsize * 1024);
+ if (mem->blocksize) { + virBufferAsprintf(&buf, "block-size=%llu,", mem->blocksize * 1024); + virBufferAsprintf(&buf, "requested-size=%llu,", mem->requestedsize * 1024); + } + if (mem->uuid) { char uuidstr[VIR_UUID_STRING_BUFLEN];
diff --git a/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.x86_64-latest.args b/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.x86_64-latest.args new file mode 100644 index 0000000000..22ee1bc459 --- /dev/null +++ b/tests/qemuxml2argvdata/memory-hotplug-virtio-mem.x86_64-latest.args @@ -0,0 +1,41 @@ +LC_ALL=C \ +PATH=/bin \ +HOME=/tmp/lib/domain--1-QEMUGuest1 \ +USER=test \ +LOGNAME=test \ +XDG_DATA_HOME=/tmp/lib/domain--1-QEMUGuest1/.local/share \ +XDG_CACHE_HOME=/tmp/lib/domain--1-QEMUGuest1/.cache \ +XDG_CONFIG_HOME=/tmp/lib/domain--1-QEMUGuest1/.config \ +/usr/bin/qemu-system-i386 \ +-name guest=QEMUGuest1,debug-threads=on \ +-S \ +-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/tmp/lib/domain--1-QEMUGuest1/master-key.aes"}' \ +-machine pc,accel=kvm,usb=off,dump-guest-core=off \ +-cpu qemu64 \ +-m size=2095104k,slots=16,maxmem=1099511627776k \ +-overcommit mem-lock=off \ +-smp 2,sockets=2,dies=1,cores=1,threads=1 \ +-object '{"qom-type":"memory-backend-ram","id":"ram-node0","size":2145386496}' \ +-numa node,nodeid=0,cpus=0-1,memdev=ram-node0 \ +-object '{"qom-type":"memory-backend-ram","id":"memvirtiomem0","reserve":false,"size":1073741824}' \ +-device virtio-mem-pci,node=0,block-size=2097152,requested-size=536870912,memdev=memvirtiomem0,id=virtiomem0,bus=pci.0,addr=0x2 \ +-object '{"qom-type":"memory-backend-file","id":"memvirtiomem1","mem-path":"/dev/hugepages2M/libvirt/qemu/-1-QEMUGuest1","reserve":false,"size":2147483648,"host-nodes":[1,2,3],"policy":"bind"}' \ +-device virtio-mem-pci,node=0,block-size=2097152,requested-size=1073741824,memdev=memvirtiomem1,id=virtiomem1,bus=pci.0,addr=0x3 \ +-uuid c7a5fdbd-edaf-9455-926a-d65c16db1809 \ +-display none \ +-no-user-config \ +-nodefaults \ +-chardev socket,id=charmonitor,fd=1729,server=on,wait=off \ +-mon chardev=charmonitor,id=monitor,mode=control \ +-rtc base=utc \ +-no-shutdown \ +-no-acpi \ +-boot strict=on \ +-device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 \ +-blockdev '{"driver":"host_device","filename":"/dev/HostVG/QEMUGuest1","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \ +-blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"raw","file":"libvirt-1-storage"}' \ +-device ide-hd,bus=ide.0,unit=0,drive=libvirt-1-format,id=ide0-0-0,bootindex=1 \ +-audiodev id=audio1,driver=none \ +-device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 \ +-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \ +-msg timestamp=on diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index 74af93b08f..23f4a8471f 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -3143,6 +3143,7 @@ mymain(void) ARG_END); DO_TEST_CAPS_VER("memory-hotplug-virtio-pmem", "5.2.0"); DO_TEST_CAPS_LATEST("memory-hotplug-virtio-pmem"); + DO_TEST_CAPS_LATEST("memory-hotplug-virtio-mem");
DO_TEST("machine-aeskeywrap-on-caps", QEMU_CAPS_AES_KEY_WRAP,
-- Thanks,
David / dhildenb
-- Thanks & Regards, Jing,Qi