On Thu, May 13, 2021 at 07:14:54PM +0000, Luck, Tony wrote: > > If you want this then be explicit about what it is you are making when > > building the API. Don't try to hide it under some generic idea of > > "kernel PCI DMA SVA" > > So, a special API call (that Dave can call from IDXD) to set up this > kernel PASID. With suitable documentation to explain the scope. > Maybe with a separate CONFIG option so it can be completely > stubbed out (IDXD does *NOT* "select" this option ... users have > to explicitly pick it). > > > I could easily see an admin option to "turn this off" entirely as > > being too dangerous, especially if the users have no interest in IDXD. > > And a kernel command line option to block IDXD from using that > special API ... for users on generic kernels who want to block > this use model (but still use IDXD in non-kernel cases). Users > who don't want IDXD at all can block loading of the driver.
A generic IOMMU API should not be IDXD specific, if you want to allow some special "integrated to the SOC accelerator PASID" mode then it should be a global IOMMU API and any security toggles for it should be global and unrelated to IDXD. Concurrently it seems necessary to have a solution for secure kernel PASID use under the DMA API and reserve this special mode for getting higher performance. I think you need to come with a proposal, and it is a bit alarming a noteworthy security hole was added under the guise of "kernel SVA" :( Jason _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
