On Thu, 13 Aug 2026 15:06:12 +0530
<[email protected]> wrote:
> From: Manish Honap <[email protected]>
>
> Add the vfio-cxl module that vfio-pci loads on demand for CXL Type-2
> devices. It registers a set of callbacks with vfio-pci-core at
> module_init and drops them at exit; the callbacks are stubs here and
> are filled in by later patches.
>
> VFIO_CXL depends on CXL_BUS and builds as vfio-cxl.ko, which
> request_module("vfio-cxl") resolves through MODULE_ALIAS.
>
> Signed-off-by: Manish Honap <[email protected]>
> ---
> MAINTAINERS | 7 +++++
> drivers/vfio/pci/Kconfig | 2 ++
> drivers/vfio/pci/Makefile | 2 ++
> drivers/vfio/pci/cxl/Kconfig | 11 ++++++++
> drivers/vfio/pci/cxl/Makefile | 3 ++
> drivers/vfio/pci/cxl/vfio_cxl_core.c | 41 ++++++++++++++++++++++++++++
> 6 files changed, 66 insertions(+)
> create mode 100644 drivers/vfio/pci/cxl/Kconfig
> create mode 100644 drivers/vfio/pci/cxl/Makefile
> create mode 100644 drivers/vfio/pci/cxl/vfio_cxl_core.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c665bf8f1a28..aa8cecbc4cf2 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -28312,6 +28312,13 @@ L: [email protected]
> S: Maintained
> F: drivers/vfio/cdx/*
>
> +VFIO CXL DRIVER
> +M: Manish Honap <[email protected]>
> +L: [email protected]
> +L: [email protected]
> +S: Supported
> +F: drivers/vfio/pci/cxl/
> +
> VFIO DRIVER
> M: Alex Williamson <[email protected]>
> L: [email protected]
> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> index 296bf01e185e..c3f54fc8ccc0 100644
> --- a/drivers/vfio/pci/Kconfig
> +++ b/drivers/vfio/pci/Kconfig
> @@ -70,6 +70,8 @@ source "drivers/vfio/pci/virtio/Kconfig"
>
> source "drivers/vfio/pci/nvgrace-gpu/Kconfig"
>
> +source "drivers/vfio/pci/cxl/Kconfig"
> +
> source "drivers/vfio/pci/qat/Kconfig"
>
> source "drivers/vfio/pci/xe/Kconfig"
It seems fair to put this above the variant driver Kconfigs rather than
bury it among them.
> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> index 6138f1bf241d..c3031070a1f3 100644
> --- a/drivers/vfio/pci/Makefile
> +++ b/drivers/vfio/pci/Makefile
> @@ -21,6 +21,8 @@ obj-$(CONFIG_VIRTIO_VFIO_PCI) += virtio/
>
> obj-$(CONFIG_NVGRACE_GPU_VFIO_PCI) += nvgrace-gpu/
>
> +obj-$(CONFIG_VFIO_CXL) += cxl/
> +
> obj-$(CONFIG_QAT_VFIO_PCI) += qat/
>
> obj-$(CONFIG_XE_VFIO_PCI) += xe/
Here again, cxl is a feature of vfio-pci-core. I'd promote it to
between vfio-pci-core and vfio-pci. The earlier linking also has the
benefit that in the typical case it will be available before the
builtin drivers (but keep the deferred loading behavior). Thanks,
Alex
> diff --git a/drivers/vfio/pci/cxl/Kconfig b/drivers/vfio/pci/cxl/Kconfig
> new file mode 100644
> index 000000000000..1392fa4ed15d
> --- /dev/null
> +++ b/drivers/vfio/pci/cxl/Kconfig
> @@ -0,0 +1,11 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +config VFIO_CXL
> + tristate "VFIO support for CXL Type-2 devices"
> + depends on CXL_BUS && CXL_MEM
> + select VFIO_PCI_CORE
> + help
> + Add CXL HDM handling to vfio-pci so a CXL Type-2 device, such as a
> + CXL-attached accelerator, can be assigned to a virtual machine.
> + vfio-pci loads this module on demand when it binds a CXL device.
> +
> + If you don't know what to do here, say N.
> diff --git a/drivers/vfio/pci/cxl/Makefile b/drivers/vfio/pci/cxl/Makefile
> new file mode 100644
> index 000000000000..8501bf626108
> --- /dev/null
> +++ b/drivers/vfio/pci/cxl/Makefile
> @@ -0,0 +1,3 @@
> +# SPDX-License-Identifier: GPL-2.0-only
> +obj-$(CONFIG_VFIO_CXL) += vfio-cxl.o
> +vfio-cxl-y := vfio_cxl_core.o
> diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c
> b/drivers/vfio/pci/cxl/vfio_cxl_core.c
> new file mode 100644
> index 000000000000..cbec7319452c
> --- /dev/null
> +++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c
> @@ -0,0 +1,41 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * VFIO support for CXL Type-2 devices.
> + *
> + * Copyright (c) 2026 NVIDIA Corporation & Affiliates
> + */
> +
> +#include <linux/module.h>
> +#include <linux/vfio_pci_core.h>
> +
> +static int vfio_cxl_init_device(struct vfio_pci_core_device *vdev)
> +{
> + return 0;
> +}
> +
> +static void vfio_cxl_release_device(struct vfio_pci_core_device *vdev)
> +{
> +}
> +
> +static const struct vfio_cxl_ops vfio_cxl_ops = {
> + .init_device = vfio_cxl_init_device,
> + .release_device = vfio_cxl_release_device,
> + .owner = THIS_MODULE,
> +};
> +
> +static int __init vfio_cxl_init(void)
> +{
> + return vfio_pci_core_register_cxl_ops(&vfio_cxl_ops);
> +}
> +
> +static void __exit vfio_cxl_exit(void)
> +{
> + vfio_pci_core_unregister_cxl_ops(&vfio_cxl_ops);
> +}
> +
> +module_init(vfio_cxl_init);
> +module_exit(vfio_cxl_exit);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("VFIO support for CXL Type-2 devices");
> +MODULE_ALIAS("vfio-cxl");
