[PATCH v5 0/3] Enable QEMU NVMe userspace driver on s390x

[Farhan Ali <alifm@linux.ibm.com>]

Hi,

Recently on s390x we have enabled mmap support for vfio-pci devices [1].
This allows us to take advantage and use userspace drivers on s390x. However,
on s390x we have special instructions for MMIO access. Starting with z15 
(and newer platforms) we have new PCI Memory I/O (MIO) instructions which 
operate on virtually mapped PCI memory spaces, and can be used from userspace.
On older platforms we would fallback to using existing system calls for MMIO access.

This patch series introduces support the PCI MIO instructions, and enables s390x
support for the userspace NVMe driver on s390x. I would appreciate any review/feedback
on the patches.

Thanks
Farhan

[1] https://lore.kernel.org/linux-s390/20250226-vfio_pci_mmap-v7-0-c5c0f1d26efd@linux.ibm.com/

ChangeLog
---------
v4 series https://lore.kernel.org/qemu-devel/20250414213616.2675-1-alifm@linux.ibm.com/
v4 -> v5
    - Fixup typo in PCI MMIO API (patch 2).

v3 series https://lore.kernel.org/qemu-devel/20250401172246.2688-1-alifm@linux.ibm.com/
v3 -> v4
    - Use generic ld/st functions for non s390x PCI access suggested by Alex (patch 2).
    - Removed R-b for patch 2 as the host PCI MMIO access API changed for non-s390x.
    Would appreciate review on this again.

v2 series https://mail.gnu.org/archive/html/qemu-devel/2025-03/msg06847.html
v2 -> v3
    - Update the PCI MMIO APIs to reflect that its PCI MMIO access on host 
as suggested by Stefan(patch 2)
    - Move s390x ifdef check to s390x_pci_mmio.h as suggested by Philippe (patch 1)
    - Add R-bs for the respective patches.

v1 series https://mail.gnu.org/archive/html/qemu-devel/2025-03/msg06596.html
v1 -> v2
    - Add 8 and 16 bit reads/writes for completeness (patch 1)
    - Introduce new QEMU PCI MMIO read/write API as suggested by Stefan (patch 2)
    - Update NVMe userspace driver to use QEMU PCI MMIO functions (patch 3)


Farhan Ali (3):
  util: Add functions for s390x mmio read/write
  include: Add a header to define host PCI MMIO functions
  block/nvme: Use host PCI MMIO API

 block/nvme.c                  |  41 +++++-----
 include/qemu/host-pci-mmio.h  | 141 ++++++++++++++++++++++++++++++++
 include/qemu/s390x_pci_mmio.h |  24 ++++++
 util/meson.build              |   2 +
 util/s390x_pci_mmio.c         | 148 ++++++++++++++++++++++++++++++++++
 5 files changed, 338 insertions(+), 18 deletions(-)
 create mode 100644 include/qemu/host-pci-mmio.h
 create mode 100644 include/qemu/s390x_pci_mmio.h
 create mode 100644 util/s390x_pci_mmio.c

-- 
2.43.0