[RFC PATCH 00/12] s390: virtio: support protected virtualization

Halil Pasic
2019-04-04T23:16:10Z

Enhanced virtualization protection technology may require the use of
bounce buffers for I/O. While support for this was built into the virtio
core, virtio-ccw wasn't changed accordingly.

Thus what needs to be done to bring virtio-ccw up to speed with respect
to this is:
* use some 'new' common virtio stuff
* make sure that virtio-ccw specific stuff uses shared memory when
talking to the hypervisor (except communication blocks like ORB, these
are handled by the hypervisor)
* make sure the DMA API does what is necessary to talk through shared
memory if we are a protected virtualization guest.
* make sure the common IO layer plays along as well (airqs, sense).

The series is structured in incremental fashion: some of the changes are
overridden by following patches. The main reason why is that this is how I
developed. But I think it ain't bad for the didactic and we are a bit more
flexible with regards to throwing out some of the stuff in the end.

Important notes:

* This is an early (WIP) RFC that does not add any function to the
kernel at his stage, as the ultravisor interactions are left out.
The purpose is getting some early feedback ASAP.

* In future these patches will depend on some code interacting with the
ultravisor (WIP by Vasily and Janosch).

* The s390 names are by no means final, and are not properly explained. Should
not hamper understanding too much. If it does please ask.

* The existing naming in the common infrastructure (kernel internal
interfaces) is pretty much based on the AMD SEV terminology. Thus the
names aren't always perfect. There might be merit to changing these
names to more abstract ones. I did not put much thought into that at
the current stage.

Testing:

Please use iommu_platform=on for any virtio devices you are going
to test this code with (so virtio actually uses the DMA API).

Looking forward to your review or any other type of input.

Halil Pasic (12):
virtio/s390: use vring_create_virtqueue
virtio/s390: DMA support for virtio-ccw
s390/mm: force swiotlb for protected virtualization
s390/cio: introduce cio DMA pool
s390/cio: add protected virtualization support to cio
s390/airq: use DMA memory for adapter interrupts
virtio/s390: use DMA memory for ccw I/O
virtio/s390: add indirection to indicators access
virtio/s390: use DMA memory for notifiers
virtio/s390: consolidate DMA allocations
virtio/s390: use the cio DMA pool
virtio/s390: make airq summary indicators DMA

arch/s390/Kconfig | 5 +
arch/s390/include/asm/Kbuild | 1 -
arch/s390/include/asm/airq.h | 2 +
arch/s390/include/asm/cio.h | 4 +
arch/s390/include/asm/dma-mapping.h | 13 ++
arch/s390/include/asm/mem_encrypt.h | 18 +++
arch/s390/mm/init.c | 44 +++++
drivers/s390/cio/airq.c | 18 ++-
drivers/s390/cio/ccwreq.c | 8 +-
drivers/s390/cio/css.c | 63 ++++++++
drivers/s390/cio/device.c | 46 ++++--
drivers/s390/cio/device_fsm.c | 40 ++---
drivers/s390/cio/device_id.c | 18 +--
drivers/s390/cio/device_ops.c | 4 +-
drivers/s390/cio/device_pgid.c | 20 +--
drivers/s390/cio/device_status.c | 24 +--
drivers/s390/cio/io_sch.h | 19 ++-
drivers/s390/virtio/virtio_ccw.c | 310 ++++++++++++++++++++----------------
18 files changed, 444 insertions(+), 213 deletions(-)
create mode 100644 arch/s390/include/asm/dma-mapping.h
create mode 100644 arch/s390/include/asm/mem_encrypt.h

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2.16.4