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However, I believe that we need a more >>> generalised concept for CoCo pre-decrypted allocators in the kernel. >>> >> There is a talk at LPC in the networking track about this [2]. This is >> exactly the type of discussion that I was hoping to have there. > > I see, thanks for point that. I plan to be in LPC, so I will aim to > attend this talk. > Great! >> >> Besides the issues mentioned in this thread we've also found that a lot >> of overhead can come only from swiotlb allocations when running many queues. >> >> I will add information about this series in my talk. Hopefully I will also >> have time to add some numbers for comparison. > > I had a quick look, I am not sure how that will shape at the end, but I > think we need a general solution beyond NICs. For example in pKVM the > bouncing is used with virtio devices, so doing this per-driver won't > really work and is not possible in some scenarios where memory is > allocated from the core kernel and then passed to the driver. > So, I was thinking the kernel relying on > CC_ATTR_MEM_ENCRYPT/force_dma_unencrypted() could detect that and > allocate pre-shared memory for those cases. > Ideally it shouldn't be per driver. But I was thinking that there should be a way for the user to provision memory for certain devices. Thanks, Dragos