[PATCH v5 00/21] KVM: s390: enable zPCI for interpretive execution

[Matthew Rosato]

Note: in this version, all IOMMU changes have been removed to be pursued
as a follow-on / in conjunction with IOMMUFD.  This series proposes to
add only exploitation of the interpretive execution facilities.

Enable interpretive execution of zPCI instructions + adapter interruption
forwarding for s390x KVM vfio-pci.  This is done by triggering a routine
when the VFIO group is associated with the KVM guest, transmitting to
firmware a special token (GISA designation) to enable that specific guest
for interpretive execution on that zPCI device.  Load/store interpreation
enablement is then controlled by userspace (based upon whether or not a
SHM bit is placed in the virtual function handle).  Adapter Event
Notification interpretation is controlled from userspace via a new KVM
ioctl.

By allowing intepretation of zPCI instructions and firmware delivery of
interrupts to guests, we can reduce the frequency of guest SIE exits for
zPCI.  

>From the perspective of guest configuration, you passthrough zPCI devices
in the same manner as before, with intepretation support being used by
default if available in kernel+qemu.

Will reply with a link to the associated QEMU series.

Changelog v4->v5:
- Remove all IOMMU changes - this series will continue to use vfio type1
  for mapping; RPCIT enhancements will be pursued as a follow-on in
  coordination with the IOMMUFD project
- Remove most of the ops from the proposed KVM ioctl -- combine the notion
  of 'start' and 'enable interpretation' into a single operation that
  occurs in response to assigning a KVM association to the VFIO group
- a new kvm ioctl is still being used to register/unregister for adapter
  event notification forwarding.  But teach it to use pin_user_pages
  instead of gfn_to_page and perform accounting.
- Because we now attempt to enable interpretation for all devices (even
  if the virtual PCI device has a SHM bit on) avoid setting the GISA for
  the device and the ECB bits for the guest on hardware without SHM.
- found a bug with "s390/pci: stash associated GISA designation", namely
  that CLP SET PCI FN (disable) expects the gisa designation to always be
  0.  Now that we set the gisa earlier, vfio-pci can trip this when
  triggering restore for ISM.
- Add a single routine to determine if interpretation support is usable
  on this host, to be used in multiple spots.
- eliminated arch/s390/include/asm/kvm_pci.h, moving most elements into
  arch/s390/kvm/pci.h with one exception to asm/kvm_host.h

Matthew Rosato (21):
  s390/sclp: detect the zPCI load/store interpretation facility
  s390/sclp: detect the AISII facility
  s390/sclp: detect the AENI facility
  s390/sclp: detect the AISI facility
  s390/airq: pass more TPI info to airq handlers
  s390/airq: allow for airq structure that uses an input vector
  s390/pci: externalize the SIC operation controls and routine
  s390/pci: stash associated GISA designation
  s390/pci: stash dtsm and maxstbl
  KVM: s390: pci: add basic kvm_zdev structure
  KVM: s390: pci: do initial setup for AEN interpretation
  KVM: s390: pci: enable host forwarding of Adapter Event Notifications
  KVM: s390: mechanism to enable guest zPCI Interpretation
  KVM: s390: pci: provide routines for enabling/disabling interrupt
    forwarding
  KVM: s390: pci: add routines to start/stop interpretive execution
  KVM: vfio: add s390x hook to register KVM guest designation
  vfio-pci/zdev: add function handle to clp base capability
  vfio-pci/zdev: different maxstbl for interpreted devices
  KVM: s390: add KVM_S390_ZPCI_OP to manage guest zPCI devices
  KVM: s390: introduce CPU feature for zPCI Interpretation
  MAINTAINERS: additional files related kvm s390 pci passthrough

 Documentation/virt/kvm/api.rst   |  45 +++
 MAINTAINERS                      |   1 +
 arch/s390/include/asm/airq.h     |   7 +-
 arch/s390/include/asm/kvm_host.h |  16 +
 arch/s390/include/asm/pci.h      |  10 +
 arch/s390/include/asm/pci_clp.h  |   9 +-
 arch/s390/include/asm/pci_insn.h |  29 +-
 arch/s390/include/asm/sclp.h     |   4 +
 arch/s390/include/asm/tpi.h      |  13 +
 arch/s390/include/uapi/asm/kvm.h |   1 +
 arch/s390/kvm/Makefile           |   1 +
 arch/s390/kvm/interrupt.c        |  95 ++++-
 arch/s390/kvm/kvm-s390.c         |  81 +++-
 arch/s390/kvm/kvm-s390.h         |  10 +
 arch/s390/kvm/pci.c              | 666 +++++++++++++++++++++++++++++++
 arch/s390/kvm/pci.h              |  86 ++++
 arch/s390/pci/pci.c              |  15 +
 arch/s390/pci/pci_clp.c          |   7 +
 arch/s390/pci/pci_insn.c         |   4 +-
 arch/s390/pci/pci_irq.c          |  48 ++-
 drivers/s390/char/sclp_early.c   |   4 +
 drivers/s390/cio/airq.c          |  12 +-
 drivers/s390/cio/qdio_thinint.c  |   6 +-
 drivers/s390/crypto/ap_bus.c     |   9 +-
 drivers/s390/virtio/virtio_ccw.c |   6 +-
 drivers/vfio/pci/vfio_pci_zdev.c |  11 +-
 include/uapi/linux/kvm.h         |  31 ++
 include/uapi/linux/vfio_zdev.h   |   7 +
 virt/kvm/vfio.c                  |  35 +-
 29 files changed, 1216 insertions(+), 53 deletions(-)
 create mode 100644 arch/s390/kvm/pci.c
 create mode 100644 arch/s390/kvm/pci.h

-- 
2.27.0