[RFC PATCH 6/7] qemu: force special features enabled for TDX guest

TDX guest requires some special parameters in qemu command line. They are "pic=no,kernel_irqchip=split" without which guest fails to bootup. PMU has a big impact to the performance of TDX guest. So always disable PMU except it's forcely enabled. Signed-off-by: Zhenzhong Duan <zhenzhong.duan(a)intel.com&gt; --- src/qemu/qemu_command.c | 6 +++++- src/qemu/qemu_validate.c | 6 ++++++ 2 files changed, 11 insertions(+), 1 deletion(-) diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c index 891d795b02..bffa3fdf10 100644 --- a/src/qemu/qemu_command.c +++ b/src/qemu/qemu_command.c @@ -6599,6 +6599,10 @@ qemuBuildCpuCommandLine(virCommand *cmd, virTristateSwitch pmu = def->features[VIR_DOMAIN_FEATURE_PMU]; virBufferAsprintf(&buf, ",pmu=%s", virTristateSwitchTypeToString(pmu)); + } else if (!def->features[VIR_DOMAIN_FEATURE_PMU] && def->tdx) { + /* PMU lead to performance drop if TDX enabled, disable PMU by default */ + virBufferAsprintf(&buf, ",pmu=%s", + virTristateSwitchTypeToString(VIR_TRISTATE_SWITCH_OFF)); } if (def->cpu && def->cpu->cache) { @@ -6975,7 +6979,7 @@ qemuBuildMachineCommandLine(virCommand *cmd, } if (def->tdx) - virBufferAddLit(&buf, ",confidential-guest-support=tdx0,kvm-type=tdx"); + virBufferAddLit(&buf, ",confidential-guest-support=tdx0,kvm-type=tdx,pic=no"); if (virQEMUCapsGet(qemuCaps, QEMU_CAPS_BLOCKDEV)) { if (priv->pflash0) diff --git a/src/qemu/qemu_validate.c b/src/qemu/qemu_validate.c index 2efd011cc0..3c3a00c7e8 100644 --- a/src/qemu/qemu_validate.c +++ b/src/qemu/qemu_validate.c @@ -202,6 +202,12 @@ qemuValidateDomainDefFeatures(const virDomainDef *def, return -1; } } + if (def->tdx && (!virQEMUCapsGet(qemuCaps, QEMU_CAPS_MACHINE_KERNEL_IRQCHIP) + || def->features[i] != VIR_DOMAIN_IOAPIC_QEMU)) { + virReportError(VIR_ERR_CONFIG_UNSUPPORTED, "%s", + _("TDX guest needs split kernel irqchip")); + return -1; + } break; case VIR_DOMAIN_FEATURE_HPT: -- 2.25.1