On Fri, 26 Apr 2019 20:32:35 +0200 Halil Pasic <pasic@xxxxxxxxxxxxx> wrote: > 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. > > Some background on technology (not part of this series) and the > terminology used. > > * Protected Virtualization (PV): > > Protected Virtualization guarantees, that non-shared memory of a guest > that operates in PV mode private to that guest. I.e. any attempts by the > hypervisor or other guests to access it will result in an exception. If > supported by the environment (machine, KVM, guest VM) a guest can decide > to change into PV mode by doing the appropriate ultravisor calls. Unlike > some other enhanced virtualization protection technology, I think that sentence misses its second part? > > * Ultravisor: > > A hardware/firmware entity that manages PV guests, and polices access to > their memory. A PV guest prospect needs to interact with the ultravisor, > to enter PV mode, and potentially to share pages (for I/O which should > be encrypted by the guest). A guest interacts with the ultravisor via so > called ultravisor calls. A hypervisor needs to interact with the > ultravisor to facilitate interpretation, emulation and swapping. A > hypervisor interacts with the ultravisor via ultravisor calls and via > the SIE state description. Generally the ultravisor sanitizes hypervisor > inputs so that the guest can not be corrupted (except for denial of > service. > > > What needs to be done > ===================== > > Thus what needs to be done to bring virtio-ccw up to speed with respect > to protected virtualization is: > * use some 'new' common virtio stuff Doing this makes sense regardless of the protected virtualization use case, and I think we should go ahead and merge those patches for 5.2. > * make sure that virtio-ccw specific stuff uses shared memory when > talking to the hypervisor (except control/communication blocks like ORB, > these are handled by the ultravisor) TBH, I'm still a bit hazy on what needs to use shared memory and what doesn't. > * 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). > > > Important notes > ================ > > * This patch set is based on Martins features branch > (git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux.git branch > 'features'). > > * Documentation is still very sketchy. I'm committed to improving this, > but I'm currently hampered by some dependencies currently. I understand, but I think this really needs more doc; also for people who want to understand the code in the future. Unfortunately lack of doc also hampers others in reviewing this :/ > > * 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). > > Change log > ========== > > RFC --> v1: > * Fixed bugs found by Connie (may_reduce and handling reduced, warning, > split move -- thanks Connie!). > * Fixed console bug found by Sebastian (thanks Sebastian!). > * Removed the completely useless duplicate of dma-mapping.h spotted by > Christoph (thanks Christoph!). > * Don't use the global DMA pool for subchannel and ccw device > owned memory as requested by Sebastian. Consequences: > * Both subchannel and ccw devices have their dma masks > now (both specifying 31 bit addressable) > * We require at least 2 DMA pages per ccw device now, most of > this memory is wasted though. > * DMA memory allocated by virtio is also 31 bit addressable now > as virtio uses the parent (which is the ccw device). > * Enabled packed ring. > * Rebased onto Martins feature branch; using the actual uv (ultravisor) > interface instead of TODO comments. > * Added some explanations to the cover letter (Connie, David). > * Squashed a couple of patches together and fixed some text stuff. > > Looking forward to your review, or any other type of input. > > Halil Pasic (10): > virtio/s390: use vring_create_virtqueue > virtio/s390: DMA support for virtio-ccw > virtio/s390: enable packed ring > s390/mm: force swiotlb for protected virtualization > s390/cio: introduce DMA pools to cio > s390/cio: add basic protected virtualization support > s390/airq: use DMA memory for adapter interrupts > virtio/s390: add indirection to indicators access > virtio/s390: use DMA memory for ccw I/O and classic notifiers > virtio/s390: make airq summary indicators DMA > > arch/s390/Kconfig | 5 + > arch/s390/include/asm/airq.h | 2 + > arch/s390/include/asm/ccwdev.h | 4 + > arch/s390/include/asm/cio.h | 11 ++ > arch/s390/include/asm/mem_encrypt.h | 18 +++ > arch/s390/mm/init.c | 50 +++++++ > drivers/s390/cio/airq.c | 18 ++- > drivers/s390/cio/ccwreq.c | 8 +- > drivers/s390/cio/cio.h | 1 + > drivers/s390/cio/css.c | 101 +++++++++++++ > drivers/s390/cio/device.c | 65 +++++++-- > drivers/s390/cio/device_fsm.c | 40 +++--- > drivers/s390/cio/device_id.c | 18 +-- > drivers/s390/cio/device_ops.c | 21 ++- > drivers/s390/cio/device_pgid.c | 20 +-- > drivers/s390/cio/device_status.c | 24 ++-- > drivers/s390/cio/io_sch.h | 21 ++- > drivers/s390/virtio/virtio_ccw.c | 275 +++++++++++++++++++----------------- > include/linux/virtio.h | 17 --- > 19 files changed, 499 insertions(+), 220 deletions(-) > create mode 100644 arch/s390/include/asm/mem_encrypt.h > _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
