Re: [PATCH] KVM: fix to not use NULL kvm->coalesced_mmio_ring in kvm_vcpu_fault()

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

Wei Yongjun wrote:
> If coalesced_mmio init fail, the kvm->coalesced_mmio_ring will be set
> to NULL. If so, we should return VM_FAULT_SIGBUS in kvm_vcpu_fault()
> even if vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET.
> 
> Signed-off-by: Wei Yongjun <yjwei@cn.fujitsu.com>
> ---
>  virt/kvm/kvm_main.c |    3 ++-
>  1 files changed, 2 insertions(+), 1 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index e758ef7..0e06a6d 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1253,7 +1253,8 @@ static int kvm_vcpu_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
>  		page = virt_to_page(vcpu->arch.pio_data);
>  #endif
>  #ifdef KVM_COALESCED_MMIO_PAGE_OFFSET
> -	else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET)
> +	else if (vmf->pgoff == KVM_COALESCED_MMIO_PAGE_OFFSET &&
> +		 vcpu->kvm->coalesced_mmio_ring)
>  		page = virt_to_page(vcpu->kvm->coalesced_mmio_ring);
>  #endif
>  	else

Btw, I am not certain if we can continue the normal path even if
kvm_coalesced_mmio_init() fails.