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

[Steve Yarmie]

d*mn! I missed the underscore - sorry - corrected in this attachment - ugh

QEMUD_CMD_FLAG_ENABLE_KVM


Steve Yarmie wrote:
> Right - I left it out of the patch by mistake. New attachment has the 
> needed test: 
>
> +    if (strstr(help, 
> "-enable-kvm"))                                                                                                                                   
>
> +        flags |= QEMUD_CMD_FLAG_ENABLEKVM;
>
> -Steve
>
> Daniel Veillard wrote:
>> On Sun, Nov 15, 2009 at 07:03:51PM -0800, Steve Yarmie wrote:
>>   
>>> 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 */
>>>     
>>
>>  Patch seems incomplete as I don't see any detection code setting up
>> QEMUD_CMD_FLAG_ENABLE_KVM in qemuCmdFlags
>>
>> Daniel
>>
>>   
>

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