[PATCH v2 01/16] KVM: Take vcpu->mutex outside vcpu_load

[David Hildenbrand]

On 29.11.2017 18:20, Paolo Bonzini wrote:
> On 29/11/2017 18:17, David Hildenbrand wrote:
>> On 29.11.2017 17:41, Christoffer Dall wrote:
>>> As we're about to call vcpu_load() from architecture-specific
>>> implementations of the KVM vcpu ioctls, but yet we access data
>>> structures protected by the vcpu->mutex in the generic code, factor
>>> this logic out from vcpu_load().
>>>
>>> Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
>>> ---
>>>  arch/x86/kvm/vmx.c       |  4 +---
>>>  arch/x86/kvm/x86.c       | 20 +++++++-------------
>>>  include/linux/kvm_host.h |  2 +-
>>>  virt/kvm/kvm_main.c      | 17 ++++++-----------
>>>  4 files changed, 15 insertions(+), 28 deletions(-)
>>>
>>> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
>>> index 714a067..e7c46d2 100644
>>> --- a/arch/x86/kvm/vmx.c
>>> +++ b/arch/x86/kvm/vmx.c
>>> @@ -9559,10 +9559,8 @@ static void vmx_switch_vmcs(struct kvm_vcpu *vcpu, struct loaded_vmcs *vmcs)
>>>  static void vmx_free_vcpu_nested(struct kvm_vcpu *vcpu)
>>>  {
>>>         struct vcpu_vmx *vmx = to_vmx(vcpu);
>>> -       int r;
>>>  
>>> -       r = vcpu_load(vcpu);
>>> -       BUG_ON(r);
>>> +       vcpu_load(vcpu);
>> I am most likely missing something, why don't we have to take the lock
>> in these cases?
> 
> See earlier discussion, at these points there can be no concurrent
> access; the file descriptor is not accessible yet, or is already gone.
> 
> Paolo

Thanks, this belongs into the patch description then.

-- 

Thanks,

David / dhildenb