Re: [RFC][PATCH 1/5] [PATCH 1/5] kvm: register in task_struct

[Fengguang Wu <fengguang.wu@intel.com>]

Hi Christian and Nikita,

On Mon, Sep 03, 2018 at 06:03:49PM +0200, Christian Borntraeger wrote:
>
>
>On 09/03/2018 04:10 PM, Nikita Leshenko wrote:
>> On September 2, 2018 5:21:15 AM, fengguang.wu@intel.com wrote:
>>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
>>> index 8b47507faab5..0c483720de8d 100644
>>> --- a/virt/kvm/kvm_main.c
>>> +++ b/virt/kvm/kvm_main.c
>>> @@ -3892,6 +3892,7 @@ static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm)
>>>  	if (type == KVM_EVENT_CREATE_VM) {
>>>  		add_uevent_var(env, "EVENT=create");
>>>  		kvm->userspace_pid = task_pid_nr(current);
>>> +		current->kvm = kvm;
>>
>> Is it OK to store `kvm` on the task_struct? What if the thread that
>> originally created the VM exits? From the documentation it seems
>> like a VM is associated with an address space and not a specific
>> thread, so maybe it should be stored on mm_struct?
>
>Yes, ioctls accessing the kvm can happen from all threads.

Good point, thank you for the tips! I'll move kvm pointer to mm_struct.

>> From Documentation/virtual/kvm/api.txt:
>>    Only run VM ioctls from the same process (address space) that was used
>>    to create the VM.
>>
>> -Nikita

Regards,
Fengguang