KVM: No need to retry for hva_to_pfn_remapped()

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>
Message-Id: <20200416155906.267462-1-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

virt/kvm/kvm_main.c

@@ -1831,8 +1831,6 @@ 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;
 
@@ -1903,15 +1901,12 @@ 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, async, write_fault, writable, &pfn);
-		if (r == -EAGAIN)
-			goto retry;
 		if (r < 0)
 			pfn = KVM_PFN_ERR_FAULT;
 	} else {