Re: [PATCH 2/2] qemu: Generate command line for tb-cache feature

Alright, here's the deal: to enable tb-cache one has to use '-accel tcg,tb-size=' which then conflicts with '-machine accel=tcg'. But sure, we can use the old -accel in this specific case. But because of how the tb-size argument is defined in QEMU there's no way for us to have a capability check. The feature was introduced in QEMU commit of v5.0.0-rc0~175^2~62 and is tied to TCG only. Therefore, I think we can live without capability check. Worst case scenario, QEMU fails to start. Resolves: https://gitlab.com/libvirt/libvirt/-/issues/229 Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com&gt; --- src/qemu/qemu_command.c | 14 ++++++- ...efault-cpu-tcg-features.x86_64-latest.args | 40 +++++++++++++++++++ tests/qemuxml2argvtest.c | 1 + 3 files changed, 54 insertions(+), 1 deletion(-) create mode 100644 tests/qemuxml2argvdata/x86_64-default-cpu-tcg-features.x86_64-latest.args diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 45278c7108..7d9cb386fd 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -7031,14 +7031,21 @@ qemuBuildMachineCommandLine(virCommand *cmd, virTristateSwitch smm = def->features[VIR_DOMAIN_FEATURE_SMM]; virCPUDef *cpu = def->cpu; g_auto(virBuffer) buf = VIR_BUFFER_INITIALIZER; + unsigned long long tb_cache = 0; size_t i; + if (def->features[VIR_DOMAIN_FEATURE_TCG] == VIR_TRISTATE_SWITCH_ON) + tb_cache = def->tcg_features->tb_cache; + virCommandAddArg(cmd, "-machine"); virBufferAdd(&buf, def->os.machine, -1); switch ((virDomainVirtType)def->virtType) { case VIR_DOMAIN_VIRT_QEMU: - virBufferAddLit(&buf, ",accel=tcg"); + /* Unfortunately, -machine doesn't accept -accel arguments and the two + * are mutually exclusive. Don't output accel= if we need -accel. */ + if (tb_cache == 0) + virBufferAddLit(&buf, ",accel=tcg");

break; case VIR_DOMAIN_VIRT_KVM: @@ -7288,6 +7295,11 @@ qemuBuildMachineCommandLine(virCommand *cmd, virCommandAddArgBuffer(cmd, &buf); + if (tb_cache > 0) { + virCommandAddArg(cmd, "-accel"); + virCommandAddArgFormat(cmd, "tcg,tb-size=%llu", tb_cache >> 10); + } + return 0; } diff --git a/tests/qemuxml2argvdata/x86_64-default-cpu-tcg-features.x86_64-latest.args b/tests/qemuxml2argvdata/x86_64-default-cpu-tcg-features.x86_64-latest.args new file mode 100644 index 0000000000..0800ea4294 --- /dev/null +++ b/tests/qemuxml2argvdata/x86_64-default-cpu-tcg-features.x86_64-latest.args @@ -0,0 +1,40 @@ +LC_ALL=C \ +PATH=/bin \ +HOME=/tmp/lib/domain--1-guest \ +USER=test \ +LOGNAME=test \ +XDG_DATA_HOME=/tmp/lib/domain--1-guest/.local/share \ +XDG_CACHE_HOME=/tmp/lib/domain--1-guest/.cache \ +XDG_CONFIG_HOME=/tmp/lib/domain--1-guest/.config \ +/usr/bin/qemu-system-x86_64 \ +-name guest=guest,debug-threads=on \ +-S \ +-object '{"qom-type":"secret","id":"masterKey0","format":"raw","file":"/tmp/lib/domain--1-guest/master-key.aes"}' \ +-machine pc-q35-6.2,usb=off,dump-guest-core=off,memory-backend=pc.ram \ +-accel tcg,tb-size=100 \ +-cpu qemu64 \ +-m 4096 \ +-object '{"qom-type":"memory-backend-ram","id":"pc.ram","size":4294967296}' \ +-overcommit mem-lock=off \ +-smp 4,sockets=4,cores=1,threads=1 \ +-uuid 1ccfd97d-5eb4-478a-bbe6-88d254c16db7 \ +-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 \ +-boot strict=on \ +-device '{"driver":"pcie-root-port","port":8,"chassis":1,"id":"pci.1","bus":"pcie.0","multifunction":true,"addr":"0x1"}' \ +-device '{"driver":"pcie-root-port","port":9,"chassis":2,"id":"pci.2","bus":"pcie.0","addr":"0x1.0x1"}' \ +-device '{"driver":"pcie-root-port","port":10,"chassis":3,"id":"pci.3","bus":"pcie.0","addr":"0x1.0x2"}' \ +-device '{"driver":"pcie-root-port","port":11,"chassis":4,"id":"pci.4","bus":"pcie.0","addr":"0x1.0x3"}' \ +-device '{"driver":"qemu-xhci","id":"usb","bus":"pci.1","addr":"0x0"}' \ +-blockdev '{"driver":"file","filename":"/var/lib/libvirt/images/guest.qcow2","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"}' \ +-blockdev '{"node-name":"libvirt-1-format","read-only":false,"driver":"qcow2","file":"libvirt-1-storage"}' \ +-device '{"driver":"virtio-blk-pci","bus":"pci.2","addr":"0x0","drive":"libvirt-1-format","id":"virtio-disk0","bootindex":1}' \ +-audiodev id=audio1,driver=none \ +-device '{"driver":"virtio-balloon-pci","id":"balloon0","bus":"pci.3","addr":"0x0"}' \ +-sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \ +-msg timestamp=on diff --git a/tests/qemuxml2argvtest.c b/tests/qemuxml2argvtest.c index 1c59395203..56ecc46071 100644 --- a/tests/qemuxml2argvtest.c +++ b/tests/qemuxml2argvtest.c @@ -3422,6 +3422,7 @@ mymain(void) DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-tcg-pc-4.2", "x86_64"); DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-kvm-q35-4.2", "x86_64"); DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-tcg-q35-4.2", "x86_64"); + DO_TEST_CAPS_ARCH_LATEST("x86_64-default-cpu-tcg-features", "x86_64"); DO_TEST_CAPS_LATEST("virtio-9p-multidevs"); DO_TEST_CAPS_LATEST("virtio-9p-createmode"); -- 2.32.0