Revert "KVM: No need to retry for hva_to_pfn_remapped()"

This reverts commit 5b494aea13fe9ec67365510c0d75835428cbb303.
If unlocked==true then the vma pointer could be invalidated, so the 2nd
follow_pfn() is potentially racy: we do need to get out and redo
find_vma_intersection().

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index da6da38..c9c6db5 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1831,6 +1831,8 @@ 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;
 
@@ -1901,12 +1903,15 @@ 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 {