[libvirt] PATCH: recent qemu-kvm requires -enable-kvm flag to activate VT optimization

Hello, Recent qemu releases require command option '-enable-qemu' in order for the kvm functionality be activated. Libvirt needs to pass this flag to qemu when starting a domain. Note that without the option, even if both the kernel and qemu support KVM, KVM will not be activated and VMs will be slow as molasses ;) I added a check in qemu_conf.c to see if `qemu -help` emits the -enable-kvm flag, and if so, use the flag accordingly. There exists a check in src/qemu/qemu_conf.c to check for the -no-kvm flag. This check works the same way. Adding the included code will not break systems where qemu does not have the option. See 'qemu -help': ... -enable-kvm enable KVM full virtualization support ... included patch against src/qemu/qemu_conf.{c,h} -Steve diff -ur libvirt/src/qemu/qemu_conf.c libvirt-qemu-enable-kvm/src/qemu/qemu_conf.c --- libvirt/src/qemu/qemu_conf.c 2009-11-08 20:57:08.438908134 -0800 +++ libvirt-qemu-enable-kvm/src/qemu/qemu_conf.c 2009-11-08 22:36:04.299921427 -0800 @@ -1602,6 +1602,7 @@ struct utsname ut; int disableKQEMU = 0; int disableKVM = 0; + int enableKVM = 0; int qargc = 0, qarga = 0; const char **qargv = NULL; int qenvc = 0, qenva = 0; @@ -1660,6 +1661,15 @@ def->virtType == VIR_DOMAIN_VIRT_QEMU) disableKVM = 1; + /* Should explicitly enable KVM if + * 1. Guest domain is 'qemu' + * 2. The qemu binary has the -enable-kvm flag + * NOTE: user must be responsible to load the kvm modules + */ + if ((qemuCmdFlags & QEMUD_CMD_FLAG_ENABLE_KVM) && + def->virtType == VIR_DOMAIN_VIRT_QEMU) + enableKVM = 1; + /* * Need to force a 32-bit guest CPU type if * @@ -1787,6 +1797,8 @@ ADD_ARG_LIT("-no-kqemu"); if (disableKVM) ADD_ARG_LIT("-no-kvm"); + if (enableKVM) + ADD_ARG_LIT("-enable-kvm"); ADD_ARG_LIT("-m"); ADD_ARG_LIT(memory); if (def->hugepage_backed) { diff -ur libvirt/src/qemu/qemu_conf.h libvirt-qemu-enable-kvm/src/qemu/qemu_conf.h --- libvirt/src/qemu/qemu_conf.h 2009-11-08 20:57:08.438908134 -0800 +++ libvirt-qemu-enable-kvm/src/qemu/qemu_conf.h 2009-11-08 14:57:39.000000000 -0800 @@ -73,6 +73,7 @@ QEMUD_CMD_FLAG_XEN_DOMID = (1 << 20), /* -xen-domid (new style xen integration) */ QEMUD_CMD_FLAG_MIGRATE_QEMU_UNIX = (1 << 21), /* Does qemu support unix domain sockets for migration? */ QEMUD_CMD_FLAG_CHARDEV = (1 << 22), /* Is the new -chardev arg available */ + QEMUD_CMD_FLAG_ENABLE_KVM = (1 << 23), /* Is the -enable-kvm flag available to "enable KVM full virtualization support" */ }; /* Main driver state */