On Sat, Aug 01, 2020 at 01:20:07AM -0700, David Rientjes wrote: > To follow-up on this, the introduction of the DMA atomic pools in 5.8 > fixes an issue for any AMD SEV enabled guest that has a driver that > requires atomic DMA allocations (for us, nvme) because runtime decryption > of memory allocated through the DMA API may block. This manifests itself > as "sleeping in invalid context" BUGs for any confidential VM user in > cloud. > > I unfortunately don't have Amit's device to be able to independently debug > this issue and certainly could not have done a better job at working the > bug than Nicolas and Christoph have done so far. I'm as baffled by the > results as anybody else. > > I fully understand the no regressions policy. I'd also ask that we > consider that *all* SEV guests are currently broken if they use nvme or > any other driver that does atomic DMA allocations. It's an extremely > serious issue for cloud. If there is *anything* that I can do to make > forward progress on this issue for 5.8, including some of the workarounds > above that Amit requested, I'd be very happy to help. Christoph will make > the right decision for DMA in 5.8, but I simply wanted to state how > critical working SEV guests are to users.
I'm between a rock and a hard place here. If we simply want to revert commits as-is to make sure both the Raspberry Pi 4 and thone phone do not regress we'll have to go all the way back and revert the whole SEV pool support. I could try to manual revert of the multiple pool support, but it is very late for that. Or maybe Linus has decided to cut a -rc8 which would give us a little more time. - _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu