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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Sat, 1 Aug 2020 at 14:27, Christoph Hellwig wrote: > > 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. Hi, I found the problematic memory region. It was a memory chunk reserved/removed in the downstream tree but was seemingly reserved upstream for different drivers. I failed to calculate the length of the total region reserved downstream correctly. And there was still a portion of memory left unmarked, which I should have marked as reserved in my testing earlier today. Sorry for all the noise and thanks Nicolas, Christoph and David for your patience. Regards, Amit Pundir > > 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