Re: [PATCH 8/9] vfio/pci: export nvlink2 support into vendor vfio_pci drivers

[Alexey Kardashevskiy <aik@xxxxxxxxx>]

On 09/03/2021 19:33, Max Gurtovoy wrote:
> The new drivers introduced are nvlink2gpu_vfio_pci.ko and
> npu2_vfio_pci.ko.
> The first will be responsible for providing special extensions for
> NVIDIA GPUs with NVLINK2 support for P9 platform (and others in the
> future). The last will be responsible for POWER9 NPU2 unit (NVLink2 host
> bus adapter).
>
> Also, preserve backward compatibility for users that were binding
> NVLINK2 devices to vfio_pci.ko. Hopefully this compatibility layer will
> be dropped in the future
>
> Signed-off-by: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
> ---
>   drivers/vfio/pci/Kconfig                      |  28 +++-
>   drivers/vfio/pci/Makefile                     |   7 +-
>   .../pci/{vfio_pci_npu2.c => npu2_vfio_pci.c}  | 144 ++++++++++++++++-
>   drivers/vfio/pci/npu2_vfio_pci.h              |  24 +++
>   ...pci_nvlink2gpu.c => nvlink2gpu_vfio_pci.c} | 149 +++++++++++++++++-
>   drivers/vfio/pci/nvlink2gpu_vfio_pci.h        |  24 +++
>   drivers/vfio/pci/vfio_pci.c                   |  61 ++++++-
>   drivers/vfio/pci/vfio_pci_core.c              |  18 ---
>   drivers/vfio/pci/vfio_pci_core.h              |  14 --
>   9 files changed, 422 insertions(+), 47 deletions(-)
>   rename drivers/vfio/pci/{vfio_pci_npu2.c => npu2_vfio_pci.c} (64%)
>   create mode 100644 drivers/vfio/pci/npu2_vfio_pci.h
>   rename drivers/vfio/pci/{vfio_pci_nvlink2gpu.c => nvlink2gpu_vfio_pci.c} (67%)
>   create mode 100644 drivers/vfio/pci/nvlink2gpu_vfio_pci.h
>
> diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
> index 829e90a2e5a3..88c89863a205 100644
> --- a/drivers/vfio/pci/Kconfig
> +++ b/drivers/vfio/pci/Kconfig
> @@ -48,8 +48,30 @@ config VFIO_PCI_IGD
>   
>   	  To enable Intel IGD assignment through vfio-pci, say Y.
>   
> -config VFIO_PCI_NVLINK2
> -	def_bool y
> +config VFIO_PCI_NVLINK2GPU
> +	tristate "VFIO support for NVIDIA NVLINK2 GPUs"
>   	depends on VFIO_PCI_CORE && PPC_POWERNV
>   	help
> -	  VFIO PCI support for P9 Witherspoon machine with NVIDIA V100 GPUs
> +	  VFIO PCI driver for NVIDIA NVLINK2 GPUs with specific extensions
> +	  for P9 Witherspoon machine.
> +
> +config VFIO_PCI_NPU2
> +	tristate "VFIO support for IBM NPU host bus adapter on P9"
> +	depends on VFIO_PCI_NVLINK2GPU && PPC_POWERNV
> +	help
> +	  VFIO PCI specific extensions for IBM NVLink2 host bus adapter on P9
> +	  Witherspoon machine.
> +
> +config VFIO_PCI_DRIVER_COMPAT
> +	bool "VFIO PCI backward compatibility for vendor specific extensions"
> +	default y
> +	depends on VFIO_PCI
> +	help
> +	  Say Y here if you want to preserve VFIO PCI backward
> +	  compatibility. vfio_pci.ko will continue to automatically use
> +	  the NVLINK2, NPU2 and IGD VFIO drivers when it is attached to
> +	  a compatible device.
> +
> +	  When N is selected the user must bind explicity to the module
> +	  they want to handle the device and vfio_pci.ko will have no
> +	  device specific special behaviors.
> diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
> index f539f32c9296..86fb62e271fc 100644
> --- a/drivers/vfio/pci/Makefile
> +++ b/drivers/vfio/pci/Makefile
> @@ -2,10 +2,15 @@
>   
>   obj-$(CONFIG_VFIO_PCI_CORE) += vfio-pci-core.o
>   obj-$(CONFIG_VFIO_PCI) += vfio-pci.o
> +obj-$(CONFIG_VFIO_PCI_NPU2) += npu2-vfio-pci.o
> +obj-$(CONFIG_VFIO_PCI_NVLINK2GPU) += nvlink2gpu-vfio-pci.o
>   
>   vfio-pci-core-y := vfio_pci_core.o vfio_pci_intrs.o vfio_pci_rdwr.o vfio_pci_config.o
>   vfio-pci-core-$(CONFIG_VFIO_PCI_IGD) += vfio_pci_igd.o
> -vfio-pci-core-$(CONFIG_VFIO_PCI_NVLINK2) += vfio_pci_nvlink2gpu.o vfio_pci_npu2.o
>   vfio-pci-core-$(CONFIG_S390) += vfio_pci_zdev.o
>   
>   vfio-pci-y := vfio_pci.o
> +
> +npu2-vfio-pci-y := npu2_vfio_pci.o
> +
> +nvlink2gpu-vfio-pci-y := nvlink2gpu_vfio_pci.o
> diff --git a/drivers/vfio/pci/vfio_pci_npu2.c b/drivers/vfio/pci/npu2_vfio_pci.c
> similarity index 64%
> rename from drivers/vfio/pci/vfio_pci_npu2.c
> rename to drivers/vfio/pci/npu2_vfio_pci.c
> index 717745256ab3..7071bda0f2b6 100644
> --- a/drivers/vfio/pci/vfio_pci_npu2.c
> +++ b/drivers/vfio/pci/npu2_vfio_pci.c
> @@ -14,19 +14,28 @@
>    *	Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
>    */
>   
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/module.h>
>   #include <linux/io.h>
>   #include <linux/pci.h>
>   #include <linux/uaccess.h>
>   #include <linux/vfio.h>
> +#include <linux/list.h>
>   #include <linux/sched/mm.h>
>   #include <linux/mmu_context.h>
>   #include <asm/kvm_ppc.h>
>   
>   #include "vfio_pci_core.h"
> +#include "npu2_vfio_pci.h"
>   
>   #define CREATE_TRACE_POINTS
>   #include "npu2_trace.h"
>   
> +#define DRIVER_VERSION  "0.1"
> +#define DRIVER_AUTHOR   "Alexey Kardashevskiy <aik@xxxxxxxxx>"
> +#define DRIVER_DESC     "NPU2 VFIO PCI - User Level meta-driver for POWER9 NPU NVLink2 HBA"
> +
>   EXPORT_TRACEPOINT_SYMBOL_GPL(vfio_pci_npu2_mmap);
>   
>   struct vfio_pci_npu2_data {
> @@ -36,6 +45,10 @@ struct vfio_pci_npu2_data {
>   	unsigned int link_speed; /* The link speed from DT's ibm,nvlink-speed */
>   };
>   
> +struct npu2_vfio_pci_device {
> +	struct vfio_pci_core_device	vdev;
> +};
> +
>   static size_t vfio_pci_npu2_rw(struct vfio_pci_core_device *vdev,
>   		char __user *buf, size_t count, loff_t *ppos, bool iswrite)
>   {
> @@ -120,7 +133,7 @@ static const struct vfio_pci_regops vfio_pci_npu2_regops = {
>   	.add_capability = vfio_pci_npu2_add_capability,
>   };
>   
> -int vfio_pci_ibm_npu2_init(struct vfio_pci_core_device *vdev)
> +static int vfio_pci_ibm_npu2_init(struct vfio_pci_core_device *vdev)
>   {
>   	int ret;
>   	struct vfio_pci_npu2_data *data;
> @@ -220,3 +233,132 @@ int vfio_pci_ibm_npu2_init(struct vfio_pci_core_device *vdev)
>   
>   	return ret;
>   }
> +
> +static void npu2_vfio_pci_release(void *device_data)
> +{
> +	struct vfio_pci_core_device *vdev = device_data;
> +
> +	mutex_lock(&vdev->reflck->lock);
> +	if (!(--vdev->refcnt)) {
> +		vfio_pci_vf_token_user_add(vdev, -1);
> +		vfio_pci_core_spapr_eeh_release(vdev);
> +		vfio_pci_core_disable(vdev);
> +	}
> +	mutex_unlock(&vdev->reflck->lock);
> +
> +	module_put(THIS_MODULE);
> +}
> +
> +static int npu2_vfio_pci_open(void *device_data)
> +{
> +	struct vfio_pci_core_device *vdev = device_data;
> +	int ret = 0;
> +
> +	if (!try_module_get(THIS_MODULE))
> +		return -ENODEV;
> +
> +	mutex_lock(&vdev->reflck->lock);
> +
> +	if (!vdev->refcnt) {
> +		ret = vfio_pci_core_enable(vdev);
> +		if (ret)
> +			goto error;
> +
> +		ret = vfio_pci_ibm_npu2_init(vdev);
> +		if (ret && ret != -ENODEV) {
> +			pci_warn(vdev->pdev,
> +				 "Failed to setup NVIDIA NV2 ATSD region\n");
> +			vfio_pci_core_disable(vdev);
> +			goto error;
> +		}
> +		ret = 0;
> +		vfio_pci_probe_mmaps(vdev);
> +		vfio_pci_core_spapr_eeh_open(vdev);
> +		vfio_pci_vf_token_user_add(vdev, 1);
> +	}
> +	vdev->refcnt++;
> +error:
> +	mutex_unlock(&vdev->reflck->lock);
> +	if (ret)
> +		module_put(THIS_MODULE);
> +	return ret;
> +}
> +
> +static const struct vfio_device_ops npu2_vfio_pci_ops = {
> +	.name		= "npu2-vfio-pci",
> +	.open		= npu2_vfio_pci_open,
> +	.release	= npu2_vfio_pci_release,
> +	.ioctl		= vfio_pci_core_ioctl,
> +	.read		= vfio_pci_core_read,
> +	.write		= vfio_pci_core_write,
> +	.mmap		= vfio_pci_core_mmap,
> +	.request	= vfio_pci_core_request,
> +	.match		= vfio_pci_core_match,
> +};
> +
> +static int npu2_vfio_pci_probe(struct pci_dev *pdev,
> +		const struct pci_device_id *id)
> +{
> +	struct npu2_vfio_pci_device *npvdev;
> +	int ret;
> +
> +	npvdev = kzalloc(sizeof(*npvdev), GFP_KERNEL);
> +	if (!npvdev)
> +		return -ENOMEM;
> +
> +	ret = vfio_pci_core_register_device(&npvdev->vdev, pdev,
> +			&npu2_vfio_pci_ops);
> +	if (ret)
> +		goto out_free;
> +
> +	return 0;
> +
> +out_free:
> +	kfree(npvdev);
> +	return ret;
> +}
> +
> +static void npu2_vfio_pci_remove(struct pci_dev *pdev)
> +{
> +	struct vfio_device *vdev = dev_get_drvdata(&pdev->dev);
> +	struct vfio_pci_core_device *core_vpdev = vfio_device_data(vdev);
> +	struct npu2_vfio_pci_device *npvdev;
> +
> +	npvdev = container_of(core_vpdev, struct npu2_vfio_pci_device, vdev);
> +
> +	vfio_pci_core_unregister_device(core_vpdev);
> +	kfree(npvdev);
> +}
> +
> +static const struct pci_device_id npu2_vfio_pci_table[] = {
> +	{ PCI_VDEVICE(IBM, 0x04ea) },
> +	{ 0, }
> +};
> +
> +static struct pci_driver npu2_vfio_pci_driver = {
> +	.name			= "npu2-vfio-pci",
> +	.id_table		= npu2_vfio_pci_table,
> +	.probe			= npu2_vfio_pci_probe,
> +	.remove			= npu2_vfio_pci_remove,
> +#ifdef CONFIG_PCI_IOV
> +	.sriov_configure	= vfio_pci_core_sriov_configure,
> +#endif
> +	.err_handler		= &vfio_pci_core_err_handlers,
> +};
> +
> +#ifdef CONFIG_VFIO_PCI_DRIVER_COMPAT
> +struct pci_driver *get_npu2_vfio_pci_driver(struct pci_dev *pdev)
> +{
> +	if (pci_match_id(npu2_vfio_pci_driver.id_table, pdev))
> +		return &npu2_vfio_pci_driver;
> +	return NULL;
> +}
> +EXPORT_SYMBOL_GPL(get_npu2_vfio_pci_driver);
> +#endif
> +
> +module_pci_driver(npu2_vfio_pci_driver);
> +
> +MODULE_VERSION(DRIVER_VERSION);
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);
> diff --git a/drivers/vfio/pci/npu2_vfio_pci.h b/drivers/vfio/pci/npu2_vfio_pci.h
> new file mode 100644
> index 000000000000..92010d340346
> --- /dev/null
> +++ b/drivers/vfio/pci/npu2_vfio_pci.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2020, Mellanox Technologies, Ltd.  All rights reserved.
> + *     Author: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
> + */
> +
> +#ifndef NPU2_VFIO_PCI_H
> +#define NPU2_VFIO_PCI_H
> +
> +#include <linux/pci.h>
> +#include <linux/module.h>
> +
> +#ifdef CONFIG_VFIO_PCI_DRIVER_COMPAT
> +#if defined(CONFIG_VFIO_PCI_NPU2) || defined(CONFIG_VFIO_PCI_NPU2_MODULE)
> +struct pci_driver *get_npu2_vfio_pci_driver(struct pci_dev *pdev);
> +#else
> +struct pci_driver *get_npu2_vfio_pci_driver(struct pci_dev *pdev)
> +{
> +	return NULL;
> +}
> +#endif
> +#endif
> +
> +#endif /* NPU2_VFIO_PCI_H */
> diff --git a/drivers/vfio/pci/vfio_pci_nvlink2gpu.c b/drivers/vfio/pci/nvlink2gpu_vfio_pci.c
> similarity index 67%
> rename from drivers/vfio/pci/vfio_pci_nvlink2gpu.c
> rename to drivers/vfio/pci/nvlink2gpu_vfio_pci.c
> index 6dce1e78ee82..84a5ac1ce8ac 100644
> --- a/drivers/vfio/pci/vfio_pci_nvlink2gpu.c
> +++ b/drivers/vfio/pci/nvlink2gpu_vfio_pci.c
> @@ -1,6 +1,6 @@
>   // SPDX-License-Identifier: GPL-2.0-only
>   /*
> - * VFIO PCI NVIDIA Whitherspoon GPU support a.k.a. NVLink2.
> + * VFIO PCI NVIDIA NVLink2 GPUs support.
>    *
>    * Copyright (C) 2018 IBM Corp.  All rights reserved.
>    *     Author: Alexey Kardashevskiy <aik@xxxxxxxxx>
> @@ -12,6 +12,9 @@
>    *	Author: Alex Williamson <alex.williamson@xxxxxxxxxx>
>    */
>   
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/module.h>
>   #include <linux/io.h>
>   #include <linux/pci.h>
>   #include <linux/uaccess.h>
> @@ -21,10 +24,15 @@
>   #include <asm/kvm_ppc.h>
>   
>   #include "vfio_pci_core.h"
> +#include "nvlink2gpu_vfio_pci.h"
>   
>   #define CREATE_TRACE_POINTS
>   #include "nvlink2gpu_trace.h"
>   
> +#define DRIVER_VERSION  "0.1"
> +#define DRIVER_AUTHOR   "Alexey Kardashevskiy <aik@xxxxxxxxx>"
> +#define DRIVER_DESC     "NVLINK2GPU VFIO PCI - User Level meta-driver for NVIDIA NVLink2 GPUs"
> +
>   EXPORT_TRACEPOINT_SYMBOL_GPL(vfio_pci_nvgpu_mmap_fault);
>   EXPORT_TRACEPOINT_SYMBOL_GPL(vfio_pci_nvgpu_mmap);
>   
> @@ -39,6 +47,10 @@ struct vfio_pci_nvgpu_data {
>   	struct notifier_block group_notifier;
>   };
>   
> +struct nv_vfio_pci_device {
> +	struct vfio_pci_core_device	vdev;
> +};
> +
>   static size_t vfio_pci_nvgpu_rw(struct vfio_pci_core_device *vdev,
>   		char __user *buf, size_t count, loff_t *ppos, bool iswrite)
>   {
> @@ -207,7 +219,8 @@ static int vfio_pci_nvgpu_group_notifier(struct notifier_block *nb,
>   	return NOTIFY_OK;
>   }
>   
> -int vfio_pci_nvidia_v100_nvlink2_init(struct vfio_pci_core_device *vdev)
> +static int
> +vfio_pci_nvidia_v100_nvlink2_init(struct vfio_pci_core_device *vdev)
>   {
>   	int ret;
>   	u64 reg[2];
> @@ -293,3 +306,135 @@ int vfio_pci_nvidia_v100_nvlink2_init(struct vfio_pci_core_device *vdev)
>   
>   	return ret;
>   }
> +
> +static void nvlink2gpu_vfio_pci_release(void *device_data)
> +{
> +	struct vfio_pci_core_device *vdev = device_data;
> +
> +	mutex_lock(&vdev->reflck->lock);
> +	if (!(--vdev->refcnt)) {
> +		vfio_pci_vf_token_user_add(vdev, -1);
> +		vfio_pci_core_spapr_eeh_release(vdev);
> +		vfio_pci_core_disable(vdev);
> +	}
> +	mutex_unlock(&vdev->reflck->lock);
> +
> +	module_put(THIS_MODULE);
> +}
> +
> +static int nvlink2gpu_vfio_pci_open(void *device_data)
> +{
> +	struct vfio_pci_core_device *vdev = device_data;
> +	int ret = 0;
> +
> +	if (!try_module_get(THIS_MODULE))
> +		return -ENODEV;
> +
> +	mutex_lock(&vdev->reflck->lock);
> +
> +	if (!vdev->refcnt) {
> +		ret = vfio_pci_core_enable(vdev);
> +		if (ret)
> +			goto error;
> +
> +		ret = vfio_pci_nvidia_v100_nvlink2_init(vdev);
> +		if (ret && ret != -ENODEV) {
> +			pci_warn(vdev->pdev,
> +				 "Failed to setup NVIDIA NV2 RAM region\n");
> +			vfio_pci_core_disable(vdev);
> +			goto error;
> +		}
> +		ret = 0;
> +		vfio_pci_probe_mmaps(vdev);
> +		vfio_pci_core_spapr_eeh_open(vdev);
> +		vfio_pci_vf_token_user_add(vdev, 1);
> +	}
> +	vdev->refcnt++;
> +error:
> +	mutex_unlock(&vdev->reflck->lock);
> +	if (ret)
> +		module_put(THIS_MODULE);
> +	return ret;
> +}
> +
> +static const struct vfio_device_ops nvlink2gpu_vfio_pci_ops = {
> +	.name		= "nvlink2gpu-vfio-pci",
> +	.open		= nvlink2gpu_vfio_pci_open,
> +	.release	= nvlink2gpu_vfio_pci_release,
> +	.ioctl		= vfio_pci_core_ioctl,
> +	.read		= vfio_pci_core_read,
> +	.write		= vfio_pci_core_write,
> +	.mmap		= vfio_pci_core_mmap,
> +	.request	= vfio_pci_core_request,
> +	.match		= vfio_pci_core_match,
> +};
> +
> +static int nvlink2gpu_vfio_pci_probe(struct pci_dev *pdev,
> +		const struct pci_device_id *id)
> +{
> +	struct nv_vfio_pci_device *nvdev;
> +	int ret;
> +
> +	nvdev = kzalloc(sizeof(*nvdev), GFP_KERNEL);
> +	if (!nvdev)
> +		return -ENOMEM;
> +
> +	ret = vfio_pci_core_register_device(&nvdev->vdev, pdev,
> +			&nvlink2gpu_vfio_pci_ops);
> +	if (ret)
> +		goto out_free;
> +
> +	return 0;
> +
> +out_free:
> +	kfree(nvdev);
> +	return ret;
> +}
> +
> +static void nvlink2gpu_vfio_pci_remove(struct pci_dev *pdev)
> +{
> +	struct vfio_device *vdev = dev_get_drvdata(&pdev->dev);
> +	struct vfio_pci_core_device *core_vpdev = vfio_device_data(vdev);
> +	struct nv_vfio_pci_device *nvdev;
> +
> +	nvdev = container_of(core_vpdev, struct nv_vfio_pci_device, vdev);
> +
> +	vfio_pci_core_unregister_device(core_vpdev);
> +	kfree(nvdev);
> +}
> +
> +static const struct pci_device_id nvlink2gpu_vfio_pci_table[] = {
> +	{ PCI_VDEVICE(NVIDIA, 0x1DB1) }, /* GV100GL-A NVIDIA Tesla V100-SXM2-16GB */
> +	{ PCI_VDEVICE(NVIDIA, 0x1DB5) }, /* GV100GL-A NVIDIA Tesla V100-SXM2-32GB */
> +	{ PCI_VDEVICE(NVIDIA, 0x1DB8) }, /* GV100GL-A NVIDIA Tesla V100-SXM3-32GB */
> +	{ PCI_VDEVICE(NVIDIA, 0x1DF5) }, /* GV100GL-B NVIDIA Tesla V100-SXM2-16GB */


Where is this list from?

Also, how is this supposed to work at the boot time? Will the kernel try 
binding let's say this one and nouveau? Which one is going to win?


> +	{ 0, }


Why a comma?

> +};



> +
> +static struct pci_driver nvlink2gpu_vfio_pci_driver = {
> +	.name			= "nvlink2gpu-vfio-pci",
> +	.id_table		= nvlink2gpu_vfio_pci_table,
> +	.probe			= nvlink2gpu_vfio_pci_probe,
> +	.remove			= nvlink2gpu_vfio_pci_remove,
> +#ifdef CONFIG_PCI_IOV
> +	.sriov_configure	= vfio_pci_core_sriov_configure,
> +#endif


What is this IOV business about?


> +	.err_handler		= &vfio_pci_core_err_handlers,
> +};
> +
> +#ifdef CONFIG_VFIO_PCI_DRIVER_COMPAT
> +struct pci_driver *get_nvlink2gpu_vfio_pci_driver(struct pci_dev *pdev)
> +{
> +	if (pci_match_id(nvlink2gpu_vfio_pci_driver.id_table, pdev))
> +		return &nvlink2gpu_vfio_pci_driver;


Why do we need matching PCI ids here instead of looking at the FDT which 
will work better?


> +	return NULL;
> +}
> +EXPORT_SYMBOL_GPL(get_nvlink2gpu_vfio_pci_driver);
> +#endif
> +
> +module_pci_driver(nvlink2gpu_vfio_pci_driver);
> +
> +MODULE_VERSION(DRIVER_VERSION);
> +MODULE_LICENSE("GPL v2");
> +MODULE_AUTHOR(DRIVER_AUTHOR);
> +MODULE_DESCRIPTION(DRIVER_DESC);
> diff --git a/drivers/vfio/pci/nvlink2gpu_vfio_pci.h b/drivers/vfio/pci/nvlink2gpu_vfio_pci.h
> new file mode 100644
> index 000000000000..ebd5b600b190
> --- /dev/null
> +++ b/drivers/vfio/pci/nvlink2gpu_vfio_pci.h
> @@ -0,0 +1,24 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Copyright (c) 2020, Mellanox Technologies, Ltd.  All rights reserved.
> + *     Author: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
> + */
> +
> +#ifndef NVLINK2GPU_VFIO_PCI_H
> +#define NVLINK2GPU_VFIO_PCI_H
> +
> +#include <linux/pci.h>
> +#include <linux/module.h>
> +
> +#ifdef CONFIG_VFIO_PCI_DRIVER_COMPAT
> +#if defined(CONFIG_VFIO_PCI_NVLINK2GPU) || defined(CONFIG_VFIO_PCI_NVLINK2GPU_MODULE)
> +struct pci_driver *get_nvlink2gpu_vfio_pci_driver(struct pci_dev *pdev);
> +#else
> +struct pci_driver *get_nvlink2gpu_vfio_pci_driver(struct pci_dev *pdev)
> +{
> +	return NULL;
> +}
> +#endif
> +#endif
> +
> +#endif /* NVLINK2GPU_VFIO_PCI_H */
> diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
> index dbc0a6559914..8e81ea039f31 100644
> --- a/drivers/vfio/pci/vfio_pci.c
> +++ b/drivers/vfio/pci/vfio_pci.c
> @@ -27,6 +27,10 @@
>   #include <linux/uaccess.h>
>   
>   #include "vfio_pci_core.h"
> +#ifdef CONFIG_VFIO_PCI_DRIVER_COMPAT
> +#include "npu2_vfio_pci.h"
> +#include "nvlink2gpu_vfio_pci.h"
> +#endif
>   
>   #define DRIVER_VERSION  "0.2"
>   #define DRIVER_AUTHOR   "Alex Williamson <alex.williamson@xxxxxxxxxx>"
> @@ -142,14 +146,48 @@ static const struct vfio_device_ops vfio_pci_ops = {
>   	.match		= vfio_pci_core_match,
>   };
>   
> +/*
> + * This layer is used for backward compatibility. Hopefully it will be
> + * removed in the future.
> + */
> +static struct pci_driver *vfio_pci_get_compat_driver(struct pci_dev *pdev)
> +{
> +	switch (pdev->vendor) {
> +	case PCI_VENDOR_ID_NVIDIA:
> +		switch (pdev->device) {
> +		case 0x1db1:
> +		case 0x1db5:
> +		case 0x1db8:
> +		case 0x1df5:
> +			return get_nvlink2gpu_vfio_pci_driver(pdev);

This does not really need a switch, could simply call these 
get_xxxx_vfio_pci_driver. Thanks,


> +		default:
> +			return NULL;
> +		}
> +	case PCI_VENDOR_ID_IBM:
> +		switch (pdev->device) {
> +		case 0x04ea:
> +			return get_npu2_vfio_pci_driver(pdev);
> +		default:
> +			return NULL;
> +		}
> +	}
> +
> +	return NULL;
> +}
> +
>   static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>   {
>   	struct vfio_pci_device *vpdev;
> +	struct pci_driver *driver;
>   	int ret;
>   
>   	if (vfio_pci_is_denylisted(pdev))
>   		return -EINVAL;
>   
> +	driver = vfio_pci_get_compat_driver(pdev);
> +	if (driver)
> +		return driver->probe(pdev, id);
> +
>   	vpdev = kzalloc(sizeof(*vpdev), GFP_KERNEL);
>   	if (!vpdev)
>   		return -ENOMEM;
> @@ -167,14 +205,21 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
>   
>   static void vfio_pci_remove(struct pci_dev *pdev)
>   {
> -	struct vfio_device *vdev = dev_get_drvdata(&pdev->dev);
> -	struct vfio_pci_core_device *core_vpdev = vfio_device_data(vdev);
> -	struct vfio_pci_device *vpdev;
> -
> -	vpdev = container_of(core_vpdev, struct vfio_pci_device, vdev);
> -
> -	vfio_pci_core_unregister_device(core_vpdev);
> -	kfree(vpdev);
> +	struct pci_driver *driver;
> +
> +	driver = vfio_pci_get_compat_driver(pdev);
> +	if (driver) {
> +		driver->remove(pdev);
> +	} else {
> +		struct vfio_device *vdev = dev_get_drvdata(&pdev->dev);
> +		struct vfio_pci_core_device *core_vpdev;
> +		struct vfio_pci_device *vpdev;
> +
> +		core_vpdev = vfio_device_data(vdev);
> +		vpdev = container_of(core_vpdev, struct vfio_pci_device, vdev);
> +		vfio_pci_core_unregister_device(core_vpdev);
> +		kfree(vpdev);
> +	}
>   }
>   
>   static int vfio_pci_sriov_configure(struct pci_dev *pdev, int nr_virtfn)
> diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
> index 4de8e352df9c..f9b39abe54cb 100644
> --- a/drivers/vfio/pci/vfio_pci_core.c
> +++ b/drivers/vfio/pci/vfio_pci_core.c
> @@ -354,24 +354,6 @@ int vfio_pci_core_enable(struct vfio_pci_core_device *vdev)
>   		}
>   	}
>   
> -	if (pdev->vendor == PCI_VENDOR_ID_NVIDIA &&
> -	    IS_ENABLED(CONFIG_VFIO_PCI_NVLINK2)) {
> -		ret = vfio_pci_nvidia_v100_nvlink2_init(vdev);
> -		if (ret && ret != -ENODEV) {
> -			pci_warn(pdev, "Failed to setup NVIDIA NV2 RAM region\n");
> -			goto disable_exit;
> -		}
> -	}
> -
> -	if (pdev->vendor == PCI_VENDOR_ID_IBM &&
> -	    IS_ENABLED(CONFIG_VFIO_PCI_NVLINK2)) {
> -		ret = vfio_pci_ibm_npu2_init(vdev);
> -		if (ret && ret != -ENODEV) {
> -			pci_warn(pdev, "Failed to setup NVIDIA NV2 ATSD region\n");
> -			goto disable_exit;
> -		}
> -	}
> -
>   	return 0;
>   
>   disable_exit:
> diff --git a/drivers/vfio/pci/vfio_pci_core.h b/drivers/vfio/pci/vfio_pci_core.h
> index 8989443c3086..31f3836e606e 100644
> --- a/drivers/vfio/pci/vfio_pci_core.h
> +++ b/drivers/vfio/pci/vfio_pci_core.h
> @@ -204,20 +204,6 @@ static inline int vfio_pci_igd_init(struct vfio_pci_core_device *vdev)
>   	return -ENODEV;
>   }
>   #endif
> -#ifdef CONFIG_VFIO_PCI_NVLINK2
> -extern int vfio_pci_nvidia_v100_nvlink2_init(struct vfio_pci_core_device *vdev);
> -extern int vfio_pci_ibm_npu2_init(struct vfio_pci_core_device *vdev);
> -#else
> -static inline int vfio_pci_nvidia_v100_nvlink2_init(struct vfio_pci_core_device *vdev)
> -{
> -	return -ENODEV;
> -}
> -
> -static inline int vfio_pci_ibm_npu2_init(struct vfio_pci_core_device *vdev)
> -{
> -	return -ENODEV;
> -}
> -#endif
>   
>   #ifdef CONFIG_S390
>   extern int vfio_pci_info_zdev_add_caps(struct vfio_pci_core_device *vdev,

--
Alexey