Re: [PATCH] Activate Virtualization On Demand v2

[Alexander Graf <agraf@suse.de>]

Zhang, Xiantao wrote:
> Alexander Graf wrote:
>   
>> X86 CPUs need to have some magic happening to enable the
>> virtualization 
>> extensions on them. This magic can result in unpleasant results for
>> users, like blocking other VMMs from working (vmx) or using invalid
>> TLB 
>> entries (svm).
>>
>> Currently KVM activates virtualization when the respective kernel
>> module 
>> is loaded. This blocks us from autoloading KVM modules without
>> breaking 
>> other VMMs.
>>
>> To circumvent this problem at least a bit, this patch introduces on
>> demand activation of virtualization. This means, that instead
>> virtualization is enabled on creation of the first virtual machine
>> and disabled on removal of the last one.
>>
>> So using this, KVM can be easily autoloaded, while keeping other
>> hypervisors usable.
>>
>> v2 adds returns to non-x86 hardware_enables and adds IA64 change
>>
>> Signed-off-by: Alexander Graf <agraf@suse.de>
>> ---
>>  arch/ia64/kvm/kvm-ia64.c   |    8 +++--
>>  arch/powerpc/kvm/powerpc.c |    3 +-
>>  arch/s390/kvm/kvm-s390.c   |    3 +-
>>  arch/x86/kvm/svm.c         |   13 +++++--
>>  arch/x86/kvm/vmx.c         |    7 ++++-
>>  arch/x86/kvm/x86.c         |    4 +-
>>  include/asm-x86/kvm_host.h |    2 +-
>>  include/linux/kvm_host.h   |    2 +-
>>  virt/kvm/kvm_main.c        |   72
>>  +++++++++++++++++++++++++++++++------------ 9 files changed, 80
>> insertions(+), 34 deletions(-) 
>>
>> diff --git a/arch/ia64/kvm/kvm-ia64.c b/arch/ia64/kvm/kvm-ia64.c
>> index c25c75b..2bd79db 100644
>> --- a/arch/ia64/kvm/kvm-ia64.c
>> +++ b/arch/ia64/kvm/kvm-ia64.c
>> @@ -110,7 +110,7 @@ long ia64_pal_vp_create(u64 *vpd, u64 *host_iva,
>> u64 *opt_handler) 
>>
>>  static  DEFINE_SPINLOCK(vp_lock);
>>
>> -void kvm_arch_hardware_enable(void *garbage)
>> +int kvm_arch_hardware_enable(void *garbage)
>>  {
>>  	long  status;
>>  	long  tmp_base;
>> @@ -124,7 +124,7 @@ void kvm_arch_hardware_enable(void *garbage)
>>  	slot = ia64_itr_entry(0x3, KVM_VMM_BASE, pte, KVM_VMM_SHIFT);
>>  	local_irq_restore(saved_psr);
>>  	if (slot < 0)
>> -		return;
>> +		return -ENOMEM;
>>     
>
> Return -EINVAL maybe more accurate. Here slot < 0 means invalid or uncorrect parameters are passed to ia64_itr_entry. 
> Xiantao
>   
Okies.