Re: [PATCH 00/14] hw/vfio: Build various objects once

["Cédric Le Goater" <clg@redhat.com>]

Hello,

On 3/7/25 19:03, Philippe Mathieu-Daudé wrote:
> By doing the following changes:
> - Clean some headers up
> - Replace compile-time CONFIG_KVM check by kvm_enabled()
> - Replace compile-time CONFIG_IOMMUFD check by iommufd_builtin()
> we can build less vfio objects.
> 
> Philippe Mathieu-Daudé (14):
>    hw/vfio/common: Include missing 'system/tcg.h' header
>    hw/vfio/spapr: Do not include <linux/kvm.h>
>    hw/vfio: Compile some common objects once
>    hw/vfio: Compile more objects once
>    hw/vfio: Compile iommufd.c once
>    system: Declare qemu_[min/max]rampagesize() in 'system/hostmem.h'
>    hw/vfio: Compile display.c once
>    system/kvm: Expose kvm_irqchip_[add,remove]_change_notifier()
>    hw/vfio/pci: Convert CONFIG_KVM check to runtime one
>    system/iommufd: Introduce iommufd_builtin() helper
>    hw/vfio/pci: Check CONFIG_IOMMUFD at runtime using iommufd_builtin()
>    hw/vfio/ap: Check CONFIG_IOMMUFD at runtime using iommufd_builtin()
>    hw/vfio/ccw: Check CONFIG_IOMMUFD at runtime using iommufd_builtin()
>    hw/vfio/platform: Check CONFIG_IOMMUFD at runtime using
>      iommufd_builtin
> 
>   docs/devel/vfio-iommufd.rst  |  2 +-
>   include/exec/ram_addr.h      |  3 --
>   include/system/hostmem.h     |  3 ++
>   include/system/iommufd.h     |  8 +++++
>   include/system/kvm.h         |  8 ++---
>   target/s390x/kvm/kvm_s390x.h |  2 +-
>   accel/stubs/kvm-stub.c       | 12 ++++++++
>   hw/ppc/spapr_caps.c          |  1 +
>   hw/s390x/s390-virtio-ccw.c   |  1 +
>   hw/vfio/ap.c                 | 27 ++++++++---------
>   hw/vfio/ccw.c                | 27 ++++++++---------
>   hw/vfio/common.c             |  1 +
>   hw/vfio/iommufd.c            |  1 -
>   hw/vfio/migration.c          |  1 -
>   hw/vfio/pci.c                | 57 +++++++++++++++++-------------------
>   hw/vfio/platform.c           | 25 ++++++++--------
>   hw/vfio/spapr.c              |  4 +--
>   hw/vfio/meson.build          | 33 ++++++++++++---------
>   18 files changed, 117 insertions(+), 99 deletions(-)
> 

Patches 1-9 look ok and should be considered for the next PR if
maintainers ack patch 6 and 8.


Some comments,

vfio-amd-xgbe and vfio-calxeda-xgmac should be treated like
vfio-platform, and since vfio-platform was designed for aarch64,
these devices should not be available on arm, ppc, ppc64, riscv*,
loongarch. That said, vfio-platform and devices being deprecated in
the QEMU 10.0 cycle, we could just wait for the removal in QEMU 10.2.

How could we (simply) remove CONFIG_VFIO_IGD in hw/vfio/pci-quirks.c ?
and compile this file only once.

The vfio-pci devices are available in nearly all targets when it
only makes sense to have them in i386, x86_64, aarch64, ppc64,
where they are supported, and also possibly in ppc (tcg) and arm
(tcg) for historical reasons and just because they happen to work.
ppc (tcg) doesn't support MSIs with vfio-pci devices so I don't
think we care much.

Patches 10-14 are wrong because they remove the "iommufd" property of
the "vfio-*" devices. We can't take these.

Thanks,

C.