On Thu, 15 Dec 2011 11:28:03 +0100
Carsten Otte <cotte@xxxxxxxxxx> wrote:
> + case KVM_S390_KEYOP_SSKE:
> + if (!(vma->vm_flags & (VM_WRITE | VM_MAYWRITE))) {
> + r = -EACCES;
> + break;
> + }
Unfortunately I just realized while discussing with Heiko that a check
for VM_WRITE is not enough. We could still have a read-only pte that
points to a file backed page which is purely read-only. A write access
is allowed but would cause copy-on-write. But we set the storage key
of the original page which would make the read-only page dirty.
We need to solved the race on the dirty bit in a clean way, otherwise
there always will be a corner case.
--
blue skies,
Martin.
"Reality continues to ruin my life." - Calvin.
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