Re: [PATCH v6] kvm: make vcpu life cycle separated from kvm instance

[Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>]

(2011/12/27 17:38), Liu Ping Fan wrote:
> From: Liu Ping Fan<pingfank@linux.vnet.ibm.com>
> 
> Currently, vcpu can be destructed only when kvm instance destroyed.
> Change this to vcpu's destruction before kvm instance, so vcpu MUST
> and CAN be destroyed before kvm's destroy.

I really don't understand why this big change can be justified by only
3 lines.

> 
> Signed-off-by: Liu Ping Fan<pingfank@linux.vnet.ibm.com>
> ---
>   arch/x86/kvm/i8254.c     |   10 +++--
>   arch/x86/kvm/i8259.c     |   17 +++++--
>   arch/x86/kvm/x86.c       |   53 +++++++++++-----------
>   include/linux/kvm_host.h |   20 +++-----
>   virt/kvm/irq_comm.c      |    6 ++-
>   virt/kvm/kvm_main.c      |  110 +++++++++++++++++++++++++++++++++++-----------
>   6 files changed, 140 insertions(+), 76 deletions(-)
> 

You are introducing kvm_arch_vcpu_zap().

Then, apart from the "zap" naming issue I mentioned last time,
what about other architectures than x86?


> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index 900c763..b88d418d 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -117,6 +117,7 @@ enum {
> 
>   struct kvm_vcpu {
>   	struct kvm *kvm;
> +	struct list_head list;
>   #ifdef CONFIG_PREEMPT_NOTIFIERS
>   	struct preempt_notifier preempt_notifier;
>   #endif
> @@ -251,12 +252,14 @@ struct kvm {
>   	struct mm_struct *mm; /* userspace tied to this vm */
>   	struct kvm_memslots *memslots;
>   	struct srcu_struct srcu;
> +	struct srcu_struct srcu_vcpus;
> +

Another srcu.  This alone is worth explaining in the changelog IMO.

	Takuya

>   #ifdef CONFIG_KVM_APIC_ARCHITECTURE
>   	u32 bsp_vcpu_id;
>   #endif
> -	struct kvm_vcpu *vcpus[KVM_MAX_VCPUS];
> +	struct list_head vcpus;
>   	atomic_t online_vcpus;
> -	int last_boosted_vcpu;
> +	int last_boosted_vcpu_id;
>   	struct list_head vm_list;
>   	struct mutex lock;
>   	struct kvm_io_bus *buses[KVM_NR_BUSES];