[PATCH v6 00/21] KVM: s390: enable zPCI for interpretive execution

Matthew Rosato
2022-04-26T20:09:12Z

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.

Some minor changes are already suggested for the QEMU series, but for
now the v5 one is still compatible:

https://lore.kernel.org/kvm/20220404181726.60291-1-mjrosato@linux.ibm.com/

Changelog v5->v6:
- Add more R-b tags
- Address a leak of aift during rmmod kvm (Christian) also destroy the
associated mutex at this time
- only need to check nisc match during 2nd insmod of kvm (Pierre)
- Register for kvm notifier in vfio_pci_zdev open_device, use this to
trigger GISA (un)registration instead of via iommu_group_for_each_dev
from virt/kvm/vfio.c (Jason)
- Since we now always enable the interpretation facilities once a
passthrough PCI device is detected, let's just set the ECB during
init vm -- SHM bits will always be used to override load/store
interpretation
- Still using KVM_S390_ZPCI_OP for AEN setup/teardown; we can continue
to discuss alternatives if it makes sense, but wanted to update the
rest of the series so review can continue.

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
vfio-pci/zdev: add open/close device hooks
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 | 18 +
arch/s390/include/asm/pci.h | 12 +
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 | 87 +++-
arch/s390/kvm/kvm-s390.h | 10 +
arch/s390/kvm/pci.c | 667 +++++++++++++++++++++++++++++++
arch/s390/kvm/pci.h | 87 ++++
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_core.c | 2 +
drivers/vfio/pci/vfio_pci_zdev.c | 61 ++-
include/linux/vfio_pci_core.h | 10 +
include/uapi/linux/kvm.h | 31 ++
include/uapi/linux/vfio_zdev.h | 7 +
30 files changed, 1256 insertions(+), 52 deletions(-)
create mode 100644 arch/s390/kvm/pci.c
create mode 100644 arch/s390/kvm/pci.h

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2.27.0