Re: [PATCH 03/11] PCI: pci_stub: Suppress kernel DMA ownership auto-claiming

Christoph Hellwig
2021-11-15T13:22:47Z

On Mon, Nov 15, 2021 at 10:05:44AM +0800, Lu Baolu wrote:
> pci_stub allows the admin to block driver binding on a device and make
> it permanently shared with userspace. Since pci_stub does not do DMA,
> it is safe.

If an IOMMU is setup and dma-iommu or friends are not used nothing is
unsafe anyway, it just is that IOMMU won't work..

> However the admin must understand that using pci_stub allows
> userspace to attack whatever device it was bound to.

I don't understand this sentence at all.