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Re: [Xen-devel] [PATCH] Partially revert "x86/mm: Clean IOMMU flags from p2m-pt code"

On Wed, Aug 28, 2019 at 02:55:58PM +0000, Alexandru Stefan ISAILA wrote:
> On 28.08.2019 16:32, Roger Pau Monne wrote:
> > This partially reverts commit
> > 854a49a7486a02edae5b3e53617bace526e9c1b1 by re-adding the logic that
> > propagates changes to the domain physmap done by p2m_pt_set_entry into
> > the iommu page tables. Without this logic changes to the guest physmap
> > are not propagated to the iommu, leaving stale iommu entries that can
> > leak data, or failing to add new entries.
> > 
> > Note that this commit doesn't re-introduce iommu flags to the cpu page
> > table entries, since the logic to add/remove entries to the iommu page
> > tables is based on the p2m type and the mfn.
> This sounds good but is it still safe to use the IOMMU flag space with 
> another purpose?

Sure, please note that this partial revert doesn't add any extra flags
to the CPU page table entries, as p2m_add_iommu_flags is not


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