On Wed, Sep 04, 2019 at 02:40:44PM -0700, David Rientjes wrote: > Hi Christoph, Jens, and Ming, > > While booting a 5.2 SEV-enabled guest we have encountered the following > WARNING that is followed up by a BUG because we are in atomic context > while trying to call set_memory_decrypted:
Well, this really is a x86 / DMA API issue unfortunately. Drivers are allowed to do GFP_ATOMIC dma allocation under locks / rcu critical sections and from interrupts. And it seems like the SEV case can't handle that. We have some semi-generic code to have a fixed sized pool in kernel/dma for non-coherent platforms that have similar issues that we could try to wire up, but I wonder if there is a better way to handle the issue, so I've added Tom and the x86 maintainers. Now independent of that issue using DMA coherent memory for the nvme PRPs/SGLs doesn't actually feel very optional. We could do with normal kmalloc allocations and just sync it to the device and back. I wonder if we should create some general mempool-like helpers for that. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
