linux-kernel - Re: [PATCH v3] kvm: make vcpu life cycle separated from kvm instance

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Date:	Thu, 15 Dec 2011 11:21:37 +0800
From:	Liu ping fan <kernelfans@...il.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>, gleb@...hat.com
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org, avi@...hat.com,
	aliguori@...ibm.com, jan.kiszka@....de
Subject: Re: [PATCH v3] kvm: make vcpu life cycle separated from kvm instance

On Tue, Dec 13, 2011 at 7:36 PM, Marcelo Tosatti <mtosatti@...hat.com> wrote:
> On Mon, Dec 12, 2011 at 10:41:23AM +0800, Liu Ping Fan wrote:
>> From: Liu Ping Fan <pingfank@...ux.vnet.ibm.com>
>>
>> Currently, vcpu can be destructed only when kvm instance destroyed.
>> Change this to vcpu's destruction taken when its refcnt is zero,
>> and then vcpu MUST and CAN be destroyed before kvm's destroy.
>>
>> Signed-off-by: Liu Ping Fan <pingfank@...ux.vnet.ibm.com>
>> ---
>>  arch/x86/kvm/i8254.c     |   10 ++++--
>>  arch/x86/kvm/i8259.c     |   12 +++++--
>>  arch/x86/kvm/mmu.c       |    7 ++--
>>  arch/x86/kvm/x86.c       |   54 +++++++++++++++++++----------------
>>  include/linux/kvm_host.h |   71 ++++++++++++++++++++++++++++++++++++++++++----
>>  virt/kvm/irq_comm.c      |    7 +++-
>>  virt/kvm/kvm_main.c      |   62 +++++++++++++++++++++++++++++++++------
>>  7 files changed, 170 insertions(+), 53 deletions(-)
>
> This needs a full audit of paths that access vcpus. See for one example
> bsp_vcpu pointer.
>
Yes, I had missed it and just paid attention to the access path to
vcpu in kvm_lapic and the path used in async_pf. I will correct it
later.
BTW, I want to make it sure that because kvm_lapic will be destroyed
before vcpu, so  it is safe to bypass the access path there, and the
situation is the same in async_pf for we have called
kvm_clear_async_pf_completion_queue before zapping vcpu.  Am I right?

As to the scene like bsp_vcpu, I think that introducing refcount like
in V2 can handle it easier. Please help to review these changes in V4
which I will send a little later.

Thanks and regards
ping fan
>
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