Re: [PATCH 2/2] iommu: Use the user PGD for SVA if PTI is enabled

[Baolu Lu]

On 8/23/22 4:12 AM, Jacob Pan wrote:
> With page table isolation, the kernel manages two sets of page tables
> for each process: one for user one for kernel. When enabling SVA, the
> current x86 IOMMU drivers bind device and PASID with the kernel copy
> of the process page table.
>
> While there is no known "Meltdown" type of DMA attack, exposing
> kernel mapping to DMA intended for userspace makes the system vulnerable
> unnecessarily. It also breaks the intention of PTI.
>
> This patch replaces kernel page table PGD with the user counterpart,
> thus fulfill the promise of PTI on the DMA side.
>
> Signed-off-by: Jacob Pan<jacob.jun.pan@xxxxxxxxxxxxxxx>

Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>

Best regards,
baolu