Re: [PATCH v2 08/18] PCI/CMA: Authenticate devices on enumeration

Jason Gunthorpe
2024-07-22T12:06:49Z

On Mon, Jul 22, 2024 at 08:19:23PM +1000, Alexey Kardashevskiy wrote:

> If there is vIOMMU, then the driver in the VM can decide whether it wants
> private or shared memory for DMA, pass that new flag to dma_map() and 1)
> have DMA memory allocated from the private pool (== no page state changes)
> and 2) have C-bit set in the vIOMMU page table (which is in the VM memory).

Not all HW supports a flow like that.

> My V1 says "all IOVA below X are private and above - shared" (which is a hw
> knob in absence of vIOMMU) and I set the X to all '1's just to mark it all
> private.

Is that portable to other implementations?

Jason