linux-kernel - Re: [RFC][PATCH 1/5] [PATCH 1/5] kvm: register in task

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Message-Id: <D3FBF73C-3C33-4F94-8BBB-CE6C70B81A70@oracle.com>
Date:   Mon, 3 Sep 2018 16:10:22 +0200
From:   Nikita Leshenko <nikita.leshchenko@...cle.com>
To:     fengguang.wu@...el.com
Cc:     akpm@...ux-foundation.org, linux-mm@...ck.org,
        fengguang.wu@...el.com, dongx.peng@...el.com, jingqi.liu@...el.com,
        eddie.dong@...el.com, dave.hansen@...el.com, ying.huang@...el.com,
        bgregg@...flix.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 1/5] [PATCH 1/5] kvm: register in task_struct

On September 2, 2018 5:21:15 AM, fengguang.wu@...el.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?

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

-Nikita
>  	} else if (type == KVM_EVENT_DESTROY_VM) {
>  		add_uevent_var(env, "EVENT=destroy");
>  	}
> -- 
> 2.15.0
> 
> 
>