Re: [PATCH -v2] KVM: fix kvm_coalesced_mmio_init()'s error handling

[Wei Yongjun <yjwei@cn.fujitsu.com>]

Takuya Yoshikawa wrote:
> This version may be better.
>
> Thanks,
>   Takuya
>
> ===
> kvm_coalesced_mmio_init() keeps to hold the addresses of a coalesced mmio
> ring page and dev even after it has freed them.
>
> Also, if this function fails, though it must be rare, it seems to be
> suggesting the system's serious state.
>
> This patch changes the error handling for this function to fix these issues.
>   

We must also unregister mmu_notifier in the error path.

> Signed-off-by: Takuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
> ---
>  virt/kvm/coalesced_mmio.c |    2 ++
>  virt/kvm/kvm_main.c       |    4 +++-
>  2 files changed, 5 insertions(+), 1 deletions(-)
>
> diff --git a/virt/kvm/coalesced_mmio.c b/virt/kvm/coalesced_mmio.c
> index 5169736..11776b7 100644
> --- a/virt/kvm/coalesced_mmio.c
> +++ b/virt/kvm/coalesced_mmio.c
> @@ -119,8 +119,10 @@ int kvm_coalesced_mmio_init(struct kvm *kvm)
>  	return ret;
>  
>  out_free_dev:
> +	kvm->coalesced_mmio_dev = NULL;
>  	kfree(dev);
>  out_free_page:
> +	kvm->coalesced_mmio_ring = NULL;
>  	__free_page(page);
>  out_err:
>  	return ret;
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e758ef7..9e72067 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -419,7 +419,9 @@ static struct kvm *kvm_create_vm(void)
>  	list_add(&kvm->vm_list, &vm_list);
>  	spin_unlock(&kvm_lock);
>  #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
> -	kvm_coalesced_mmio_init(kvm);
> +	r = kvm_coalesced_mmio_init(kvm);
> +	if (r < 0)
> +		goto out_err;
>  #endif
>  out:
>  	return kvm;
>