Re: [PATCH] KVM: No need to retry for hva_to_pfn_remapped()

[Paolo Bonzini <pbonzini@redhat.com>]

On 16/04/20 17:59, Peter Xu wrote:
> hva_to_pfn_remapped() calls fixup_user_fault(), which has already
> handled the retry gracefully.  Even if "unlocked" is set to true, it
> means that we've got a VM_FAULT_RETRY inside fixup_user_fault(),
> however the page fault has already retried and we should have the pfn
> set correctly.  No need to do that again.
> 
> Signed-off-by: Peter Xu <peterx@redhat.com>
> ---
>  virt/kvm/kvm_main.c | 5 -----
>  1 file changed, 5 deletions(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 2f1f2f56e93d..6aaed69641a5 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1824,8 +1824,6 @@ static int hva_to_pfn_remapped(struct vm_area_struct *vma,
>  		r = fixup_user_fault(current, current->mm, addr,
>  				     (write_fault ? FAULT_FLAG_WRITE : 0),
>  				     &unlocked);
> -		if (unlocked)
> -			return -EAGAIN;
>  		if (r)
>  			return r;
>  
> @@ -1896,15 +1894,12 @@ static kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool *async,
>  		goto exit;
>  	}
>  
> -retry:
>  	vma = find_vma_intersection(current->mm, addr, addr + 1);
>  
>  	if (vma == NULL)
>  		pfn = KVM_PFN_ERR_FAULT;
>  	else if (vma->vm_flags & (VM_IO | VM_PFNMAP)) {
>  		r = hva_to_pfn_remapped(vma, addr, write_fault, writable, &pfn);
> -		if (r == -EAGAIN)
> -			goto retry;
>  		if (r < 0)
>  			pfn = KVM_PFN_ERR_FAULT;
>  	} else {
> 

Queued, thanks.

Paolo