Re: [PATCH v9 00/21] KVM: s390: enable zPCI for interpretive execution

From: Christian Borntraeger
Date: Fri Jul 08 2022 - 07:33:48 EST



Am 06.06.22 um 22:33 schrieb Matthew Rosato:
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 follow up with a link the most recent QEMU series.

Changelog v8->v9:
- Rebase on top of 5.19-rc1, adjust ioctl and capability defines
- s/kzdev = 0/kzdev = NULL/ (Alex)
- rename vfio_pci_zdev_open to vfio_pci_zdev_open_device (Jason)
- rename vfio_pci_zdev_release to vfio_pci_zdev_close_device (Jason)
- make vfio_pci_zdev_close_device return void, instead WARN_ON or ignore
errors in lower level function (kvm_s390_pci_unregister_kvm) (Jason)
- remove notifier accidentally left in struct zpci_dev + associated
include statment (Jason)
- Remove patch 'KVM: s390: introduce CPU feature for zPCI Interpretation'
based on discussion in QEMU thread.

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
vfio/pci: introduce CONFIG_VFIO_PCI_ZDEV_KVM
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
MAINTAINERS: additional files related kvm s390 pci passthrough

Documentation/virt/kvm/api.rst | 47 +++
MAINTAINERS | 1 +
arch/s390/include/asm/airq.h | 7 +-
arch/s390/include/asm/kvm_host.h | 23 ++
arch/s390/include/asm/pci.h | 11 +
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/kvm/Makefile | 1 +
arch/s390/kvm/interrupt.c | 96 ++++-
arch/s390/kvm/kvm-s390.c | 83 +++-
arch/s390/kvm/kvm-s390.h | 10 +
arch/s390/kvm/pci.c | 690 +++++++++++++++++++++++++++++++
arch/s390/kvm/pci.h | 88 ++++
arch/s390/pci/pci.c | 16 +
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/Kconfig | 11 +
drivers/vfio/pci/Makefile | 2 +-
drivers/vfio/pci/vfio_pci_core.c | 10 +-
drivers/vfio/pci/vfio_pci_zdev.c | 35 +-
include/linux/sched/user.h | 3 +-
include/linux/vfio_pci_core.h | 12 +-
include/uapi/linux/kvm.h | 31 ++
include/uapi/linux/vfio_zdev.h | 7 +
32 files changed, 1279 insertions(+), 56 deletions(-)
create mode 100644 arch/s390/kvm/pci.c
create mode 100644 arch/s390/kvm/pci.h

So I pulled this into a topic branch and will merge that into kvms390/next. We can
merge this topic branch into vfio-next and/or s390-next when the conflicts get
to complicated.

While pulling I fixed up the numbers for the capability to

#define KVM_CAP_S390_ZPCI_OP 221

and the doc number to

4.137 KVM_S390_ZPCI_OP

to minize struggle when doing backports.