Re: [PATCH 00/12] s390x/pci: zPCI interpretation support

[Pierre Morel <pmorel@linux.ibm.com>]

On 12/7/21 22:04, Matthew Rosato wrote:
> Note:  The first 3 patches of this series are included as pre-reqs, but
> should be pulled via a separate series.  Also, patch 5 is needed to
> support 5.16+ linux header-sync and was already done by Paolo but not
> merged yet so is thus included here as well.
> 
> For QEMU, the majority of the work in enabling instruction interpretation
> is handled via new VFIO ioctls to SET the appropriate interpretation and
> interrupt forwarding modes, and to GET the function handle to use for
> interpretive execution.
> 
> This series implements these new ioctls, as well as adding a new, optional
> 'intercept' parameter to zpci to request interpretation support not be used
> as well as an 'intassist' parameter to determine whether or not the
> firmware assist will be used for interrupt delivery or whether the host
> will be responsible for delivering all interrupts.

In which circumstances do we have an added value by not using interrupt 
delivered by firmware?


> 
> The ZPCI_INTERP CPU feature is added beginning with the z14 model to
> enable this support.
> 
> As a consequence of implementing zPCI interpretation, ISM devices now
> become eligible for passthrough (but only when zPCI interpretation is
> available).
> 
>  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.
> 
> Associated kernel series:
> https://lkml.org/lkml/2021/12/7/1179
> 
> Matthew Rosato (11):
>    s390x/pci: use a reserved ID for the default PCI group
>    s390x/pci: don't use hard-coded dma range in reg_ioat
>    s390x/pci: add supported DT information to clp response
>    Update linux headers
>    target/s390x: add zpci-interp to cpu models
>    s390x/pci: enable for load/store intepretation
>    s390x/pci: don't fence interpreted devices without MSI-X
>    s390x/pci: enable adapter event notification for interpreted devices
>    s390x/pci: use I/O Address Translation assist when interpreting
>    s390x/pci: use dtsm provided from vfio capabilities for interpreted
>      devices
>    s390x/pci: let intercept devices have separate PCI groups
> 
> Paolo Bonzini (1):
>    virtio-gpu: do not byteswap padding
> 
>   hw/s390x/s390-pci-bus.c                       | 121 +++++++++-
>   hw/s390x/s390-pci-inst.c                      | 178 +++++++++++++-
>   hw/s390x/s390-pci-vfio.c                      | 221 +++++++++++++++++-
>   include/hw/s390x/s390-pci-bus.h               |  11 +-
>   include/hw/s390x/s390-pci-clp.h               |   3 +-
>   include/hw/s390x/s390-pci-inst.h              |   2 +-
>   include/hw/s390x/s390-pci-vfio.h              |  45 ++++
>   include/hw/virtio/virtio-gpu-bswap.h          |   1 -
>   include/standard-headers/asm-x86/kvm_para.h   |   1 +
>   include/standard-headers/drm/drm_fourcc.h     | 121 +++++++++-
>   include/standard-headers/linux/ethtool.h      |  31 +++
>   include/standard-headers/linux/fuse.h         |  15 +-
>   include/standard-headers/linux/pci_regs.h     |   6 +
>   include/standard-headers/linux/virtio_gpu.h   |  18 +-
>   include/standard-headers/linux/virtio_ids.h   |  24 ++
>   include/standard-headers/linux/virtio_mem.h   |   9 +-
>   include/standard-headers/linux/virtio_vsock.h |   3 +-
>   linux-headers/asm-arm64/unistd.h              |   1 +
>   linux-headers/asm-generic/unistd.h            |  22 +-
>   linux-headers/asm-mips/unistd_n32.h           |   2 +
>   linux-headers/asm-mips/unistd_n64.h           |   2 +
>   linux-headers/asm-mips/unistd_o32.h           |   2 +
>   linux-headers/asm-powerpc/unistd_32.h         |   2 +
>   linux-headers/asm-powerpc/unistd_64.h         |   2 +
>   linux-headers/asm-s390/kvm.h                  |   1 +
>   linux-headers/asm-s390/unistd_32.h            |   2 +
>   linux-headers/asm-s390/unistd_64.h            |   2 +
>   linux-headers/asm-x86/kvm.h                   |   5 +
>   linux-headers/asm-x86/unistd_32.h             |   3 +
>   linux-headers/asm-x86/unistd_64.h             |   3 +
>   linux-headers/asm-x86/unistd_x32.h            |   3 +
>   linux-headers/linux/kvm.h                     |  41 +++-
>   linux-headers/linux/vfio.h                    |  22 ++
>   linux-headers/linux/vfio_zdev.h               |  51 ++++
>   target/s390x/cpu_features_def.h.inc           |   1 +
>   target/s390x/gen-features.c                   |   2 +
>   target/s390x/kvm/kvm.c                        |   1 +
>   37 files changed, 928 insertions(+), 52 deletions(-)
> 

-- 
Pierre Morel
IBM Lab Boeblingen