| Message ID | 20190606115127.55519-1-pasic@linux.ibm.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | s390: virtio: support protected virtualization | expand |
On Thu, 6 Jun 2019 13:51:19 +0200 Halil Pasic <pasic@linux.ibm.com> wrote: > * Documentation is still very sketchy. I'm committed to improving this, > but I'm currently hampered by some dependencies currently. Have the "dependencies" been resolved in the meantime? It probably would be a good idea to include some documentation for what needs to be dma and what doesn't somewhere in the kernel documentation (IIRC we have a s390 drivers 'book' partially generated from kerneldoc; there's some general document about the cio interfaces as well, but I'm not sure how up-to-date that is.) I think the code in here looks sane from my point of view (except for the one easy-to-fix issue I found); I would be fine with the virtio-ccw patches making it into the kernel via the s390 tree (and not via the virtio tree).
On Tue, Jun 11, 2019 at 12:37:40PM +0200, Cornelia Huck wrote: > On Thu, 6 Jun 2019 13:51:19 +0200 > Halil Pasic <pasic@linux.ibm.com> wrote: > > > * Documentation is still very sketchy. I'm committed to improving this, > > but I'm currently hampered by some dependencies currently. > > Have the "dependencies" been resolved in the meantime? It probably > would be a good idea to include some documentation for what needs to be > dma and what doesn't somewhere in the kernel documentation (IIRC we > have a s390 drivers 'book' partially generated from kerneldoc; there's > some general document about the cio interfaces as well, but I'm not > sure how up-to-date that is.) > > I think the code in here looks sane from my point of view (except for > the one easy-to-fix issue I found); I would be fine with the virtio-ccw > patches making it into the kernel via the s390 tree (and not via the > virtio tree). Yes, me too.
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. * 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 * 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) * 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. * 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). @Sebastian: I kept your r-b on patch 2 "s390/cio: introduce DMA pools to cio" despite the small changes pointed out below. Please do complain if it ain't OK for you! Change log ========== v3 --> v4 * fixed cleanup in css_bus_init() (Connie) * made cio.h include genalloc.h instead of a forward declaration (Connie) * added comments about dma_mask/coherent_dma_mask values (Connie) * fixed error handling in virtio_ccw_init() (Connie) * got rid of the *vc_dma* wrappers (Connie) * added some Reviewed-bys * rebased on top of current master, no changes were necessary v2 --> v3: * patch 2/8 potential cio_dma_pool_init() returning NULL issue fixed potential cio_gp_dma_create() returning NULL issue fixed warning issues with doc type comments fixed unused define statement removed * patch 3/8 potential cio_gp_dma_create() returning NULL issue fixed whitespace issue fixed warning issues with doc type comments fixed * patch 8/8 potential cio_dma_zalloc() returning NULL issue fixed v1 --> v2: * patch "virtio/s390: use vring_create_virtqueue" went already upstream * patch "virtio/s390: DMA support for virtio-ccw" went already upstream * patch "virtio/s390: enable packed ring" went already upstream * Made dev.dma_mask point to dev.coherent_dma_mask for css, subchannel and ccw devices. * While rebasing 's390/airq: use DMA memory for adapter interrupts' the newly introduced kmem_cache was replaced with an equivalent dma_pool; the kalloc() allocations are now replaced with cio_dma_zalloc() allocations to avoid wasting almost a full page. * Made virtio-ccw use the new AIRQ_IV_CACHELINE flag. * fixed all remaining checkpatch issues 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. Halil Pasic (8): 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: use cacheline aligned airq bit vectors 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 | 47 ++++++ drivers/s390/cio/airq.c | 32 ++-- drivers/s390/cio/ccwreq.c | 9 +- drivers/s390/cio/cio.h | 2 + drivers/s390/cio/css.c | 132 ++++++++++++++- drivers/s390/cio/device.c | 68 ++++++-- drivers/s390/cio/device_fsm.c | 49 +++--- drivers/s390/cio/device_id.c | 20 ++- drivers/s390/cio/device_ops.c | 21 ++- drivers/s390/cio/device_pgid.c | 22 +-- drivers/s390/cio/device_status.c | 24 +-- drivers/s390/cio/io_sch.h | 20 ++- drivers/s390/virtio/virtio_ccw.c | 248 +++++++++++++++------------- 18 files changed, 534 insertions(+), 200 deletions(-) create mode 100644 arch/s390/include/asm/mem_encrypt.h