[PATCH 12/13] vfio/nvidia-vgpu: add the NVIDIA vGPU VFIO variant driver

[Zhi Wang <zhiw@nvidia.com>]

NVIDIA vGPU VFs require their open, reset, and close lifecycle to be
coordinated with the PF-side nova-core driver.

Add a VFIO PCI variant driver that binds NVIDIA devices only through
driver_override and rejects non-VFs. Delegate instance lifecycle
operations to nova-core, present the firmware-selected device and
subsystem IDs in configuration-space reads, and adjust the reported BAR1
aperture to the assigned profile. Use vfio-pci-core for the remaining
VFIO operations.

Signed-off-by: Zhi Wang <zhiw@nvidia.com>
---
 drivers/vfio/pci/Kconfig              |   2 +
 drivers/vfio/pci/Makefile             |   2 +
 drivers/vfio/pci/nvidia-vgpu/Kconfig  |  16 ++
 drivers/vfio/pci/nvidia-vgpu/Makefile |   2 +
 drivers/vfio/pci/nvidia-vgpu/main.c   | 253 ++++++++++++++++++++++++++
 5 files changed, 275 insertions(+)
 create mode 100644 drivers/vfio/pci/nvidia-vgpu/Kconfig
 create mode 100644 drivers/vfio/pci/nvidia-vgpu/Makefile
 create mode 100644 drivers/vfio/pci/nvidia-vgpu/main.c

diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index 296bf01e185e..b48d8d1af42a 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -74,4 +74,6 @@ source "drivers/vfio/pci/qat/Kconfig"
 
 source "drivers/vfio/pci/xe/Kconfig"
 
+source "drivers/vfio/pci/nvidia-vgpu/Kconfig"
+
 endmenu
diff --git a/drivers/vfio/pci/Makefile b/drivers/vfio/pci/Makefile
index 6138f1bf241d..f3498e541555 100644
--- a/drivers/vfio/pci/Makefile
+++ b/drivers/vfio/pci/Makefile
@@ -24,3 +24,5 @@ obj-$(CONFIG_NVGRACE_GPU_VFIO_PCI) += nvgrace-gpu/
 obj-$(CONFIG_QAT_VFIO_PCI) += qat/
 
 obj-$(CONFIG_XE_VFIO_PCI) += xe/
+
+obj-$(CONFIG_NVIDIA_VGPU_VFIO_PCI) += nvidia-vgpu/
diff --git a/drivers/vfio/pci/nvidia-vgpu/Kconfig b/drivers/vfio/pci/nvidia-vgpu/Kconfig
new file mode 100644
index 000000000000..098822d32380
--- /dev/null
+++ b/drivers/vfio/pci/nvidia-vgpu/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config NVIDIA_VGPU_VFIO_PCI
+	tristate "VFIO support for the NVIDIA vGPU"
+	depends on NOVA_CORE && PCI_IOV
+	select VFIO_PCI_CORE
+	help
+	  This option enables VFIO (Virtual Function I/O) support for
+	  NVIDIA virtual GPUs (vGPU). It allows the assignment of a virtual
+	  GPU instance to userspace applications via VFIO, typically used
+	  with hypervisors such as KVM and device emulators like QEMU.
+
+	  The NVIDIA vGPU allows a physical GPU to be partitioned into
+	  multiple virtual GPUs, each of which can be passed to a virtual
+	  machine as a PCI device using the standard VFIO infrastructure.
+
+	  If you don't know what to do here, say N.
diff --git a/drivers/vfio/pci/nvidia-vgpu/Makefile b/drivers/vfio/pci/nvidia-vgpu/Makefile
new file mode 100644
index 000000000000..193cc801a081
--- /dev/null
+++ b/drivers/vfio/pci/nvidia-vgpu/Makefile
@@ -0,0 +1,2 @@
+obj-$(CONFIG_NVIDIA_VGPU_VFIO_PCI) += nvidia-vgpu-vfio-pci.o
+nvidia-vgpu-vfio-pci-y := main.o
diff --git a/drivers/vfio/pci/nvidia-vgpu/main.c b/drivers/vfio/pci/nvidia-vgpu/main.c
new file mode 100644
index 000000000000..d8626644f952
--- /dev/null
+++ b/drivers/vfio/pci/nvidia-vgpu/main.c
@@ -0,0 +1,253 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/pci.h>
+#include <linux/pid.h>
+#include <linux/vfio_pci_core.h>
+#include <drm/nvidia_vgpu.h>
+
+static int nvidia_vgpu_fb_bar_index(struct pci_dev *pdev)
+{
+	if (pci_resource_flags(pdev, 0) & IORESOURCE_MEM_64)
+		return 2;
+	return 1;
+}
+
+struct nvidia_vgpu_pci_core_device {
+	struct vfio_pci_core_device core_device;
+	struct nvidia_vgpu_type_info type_info;
+	unsigned int gfid;
+};
+
+static inline unsigned int nvidia_vgpu_vf_dbdf(struct pci_dev *vf)
+{
+	return ((u32)pci_domain_nr(vf->bus) << 16) | pci_dev_id(vf);
+}
+
+static int nvidia_vgpu_open_device(struct vfio_device *core_vdev)
+{
+	struct nvidia_vgpu_pci_core_device *nvdev = container_of(
+		core_vdev, struct nvidia_vgpu_pci_core_device, core_device.vdev);
+	struct pci_dev *vf = to_pci_dev(core_vdev->dev);
+	struct nvidia_vgpu_type_info type_info;
+	int ret;
+
+	if (!vf->is_virtfn)
+		return -ENODEV;
+
+	ret = vfio_pci_core_enable(&nvdev->core_device);
+	if (ret)
+		return ret;
+
+	ret = nvidia_vgpu_open(pci_physfn(vf), nvdev->gfid,
+			       nvidia_vgpu_vf_dbdf(vf), task_tgid_nr(current),
+			       &type_info);
+	if (ret) {
+		vfio_pci_core_disable(&nvdev->core_device);
+		return ret;
+	}
+
+	nvdev->type_info = type_info;
+	pci_dbg(vf, "vgpu open: dev_id=0x%x subsys_id=0x%x bar1_length=0x%llx\n",
+		type_info.pci_dev_id, type_info.pci_subsys_id,
+		type_info.bar1_length);
+	vfio_pci_core_finish_enable(&nvdev->core_device);
+	return 0;
+}
+
+static void nvidia_vgpu_close_device(struct vfio_device *core_vdev)
+{
+	struct nvidia_vgpu_pci_core_device *nvdev = container_of(
+		core_vdev, struct nvidia_vgpu_pci_core_device, core_device.vdev);
+	struct pci_dev *vf = to_pci_dev(core_vdev->dev);
+
+	nvidia_vgpu_close(pci_physfn(vf), nvdev->gfid);
+	vfio_pci_core_close_device(core_vdev);
+}
+
+static ssize_t nvidia_vgpu_pci_read_config(struct vfio_device *core_vdev,
+					   char __user *buf, size_t count,
+					   loff_t *ppos)
+{
+	struct nvidia_vgpu_pci_core_device *nvdev = container_of(
+		core_vdev, struct nvidia_vgpu_pci_core_device, core_device.vdev);
+	struct nvidia_vgpu_type_info *ti = &nvdev->type_info;
+	loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
+	size_t register_offset;
+	loff_t copy_offset;
+	size_t copy_count;
+	__le16 val16;
+	int ret;
+
+	ret = vfio_pci_core_read(core_vdev, buf, count, ppos);
+	if (ret < 0)
+		return ret;
+
+	if (vfio_pci_core_range_intersect_range(pos, count, PCI_DEVICE_ID,
+						sizeof(val16), &copy_offset,
+						&copy_count, &register_offset)) {
+		val16 = cpu_to_le16(ti->pci_dev_id);
+		if (copy_to_user(buf + copy_offset,
+				 (void *)&val16 + register_offset, copy_count))
+			return -EFAULT;
+	}
+
+	if (vfio_pci_core_range_intersect_range(pos, count, PCI_SUBSYSTEM_ID,
+						sizeof(val16), &copy_offset,
+						&copy_count, &register_offset)) {
+		val16 = cpu_to_le16(ti->pci_subsys_id);
+		if (copy_to_user(buf + copy_offset,
+				 (void *)&val16 + register_offset, copy_count))
+			return -EFAULT;
+	}
+
+	return count;
+}
+
+static ssize_t nvidia_vgpu_pci_read(struct vfio_device *core_vdev,
+				    char __user *buf, size_t count,
+				    loff_t *ppos)
+{
+	unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos);
+
+	if (index == VFIO_PCI_CONFIG_REGION_INDEX)
+		return nvidia_vgpu_pci_read_config(core_vdev, buf, count, ppos);
+
+	return vfio_pci_core_read(core_vdev, buf, count, ppos);
+}
+
+static int nvidia_vgpu_bar1_size(struct nvidia_vgpu_pci_core_device *nvdev,
+				 u64 *size)
+{
+	if (check_shl_overflow(nvdev->type_info.bar1_length, 20, size))
+		return -EOVERFLOW;
+
+	return 0;
+}
+
+static int nvidia_vgpu_get_region_info(struct vfio_device *core_vdev,
+				       struct vfio_region_info *info,
+				       struct vfio_info_cap *caps)
+{
+	int ret;
+
+	ret = vfio_pci_ioctl_get_region_info(core_vdev, info, caps);
+	if (ret)
+		return ret;
+
+	if (info->index == nvidia_vgpu_fb_bar_index(
+		to_pci_dev(core_vdev->dev)) && info->size) {
+		struct nvidia_vgpu_pci_core_device *nvdev = container_of(
+			core_vdev, struct nvidia_vgpu_pci_core_device,
+			core_device.vdev);
+		u64 vgpu_bar1;
+
+		ret = nvidia_vgpu_bar1_size(nvdev, &vgpu_bar1);
+		if (ret)
+			return ret;
+
+		if (vgpu_bar1 && vgpu_bar1 < info->size)
+			info->size = vgpu_bar1;
+	}
+
+	return 0;
+}
+
+static long nvidia_vgpu_pci_ioctl(struct vfio_device *core_vdev,
+				  unsigned int cmd, unsigned long arg)
+{
+	if (cmd == VFIO_DEVICE_RESET) {
+		struct nvidia_vgpu_pci_core_device *nvdev = container_of(
+			core_vdev, struct nvidia_vgpu_pci_core_device,
+			core_device.vdev);
+		struct pci_dev *vf = to_pci_dev(core_vdev->dev);
+		int ret;
+
+		ret = nvidia_vgpu_reset(pci_physfn(vf), nvdev->gfid);
+		if (ret)
+			return ret;
+	}
+
+	return vfio_pci_core_ioctl(core_vdev, cmd, arg);
+}
+
+static const struct vfio_device_ops nvidia_vgpu_pci_ops = {
+	.name		= "nvidia-vgpu-vfio-pci",
+	.init		= vfio_pci_core_init_dev,
+	.release	= vfio_pci_core_release_dev,
+	.open_device	= nvidia_vgpu_open_device,
+	.close_device	= nvidia_vgpu_close_device,
+	.ioctl		= nvidia_vgpu_pci_ioctl,
+	.get_region_info_caps = nvidia_vgpu_get_region_info,
+	.device_feature	= vfio_pci_core_ioctl_feature,
+	.read		= nvidia_vgpu_pci_read,
+	.write		= vfio_pci_core_write,
+	.mmap		= vfio_pci_core_mmap,
+	.request	= vfio_pci_core_request,
+	.match		= vfio_pci_core_match,
+	.match_token_uuid = vfio_pci_core_match_token_uuid,
+	.bind_iommufd	= vfio_iommufd_physical_bind,
+	.unbind_iommufd	= vfio_iommufd_physical_unbind,
+	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
+	.detach_ioas	= vfio_iommufd_physical_detach_ioas,
+};
+
+static int nvidia_vgpu_pci_probe(struct pci_dev *pdev,
+				 const struct pci_device_id *id)
+{
+	struct nvidia_vgpu_pci_core_device *nvdev;
+	int vf_id;
+	int ret;
+
+	if (!pdev->is_virtfn)
+		return -ENODEV;
+
+	vf_id = pci_iov_vf_id(pdev);
+	if (vf_id < 0)
+		return vf_id;
+
+	nvdev = vfio_alloc_device(nvidia_vgpu_pci_core_device, core_device.vdev,
+				  &pdev->dev, &nvidia_vgpu_pci_ops);
+	if (IS_ERR(nvdev))
+		return PTR_ERR(nvdev);
+
+	nvdev->gfid = vf_id + 1;
+	dev_set_drvdata(&pdev->dev, &nvdev->core_device);
+	ret = vfio_pci_core_register_device(&nvdev->core_device);
+	if (ret)
+		goto out_put_vdev;
+
+	return 0;
+
+out_put_vdev:
+	vfio_put_device(&nvdev->core_device.vdev);
+	return ret;
+}
+
+static void nvidia_vgpu_pci_remove(struct pci_dev *pdev)
+{
+	struct vfio_pci_core_device *core_device = dev_get_drvdata(&pdev->dev);
+
+	vfio_pci_core_unregister_device(core_device);
+	vfio_put_device(&core_device->vdev);
+}
+
+static const struct pci_device_id nvidia_vgpu_pci_table[] = {
+	/* Placeholder: match all NVIDIA VFs (vendor 0x10de) */
+	{ PCI_DRIVER_OVERRIDE_DEVICE_VFIO(PCI_VENDOR_ID_NVIDIA, PCI_ANY_ID) },
+	{}
+};
+MODULE_DEVICE_TABLE(pci, nvidia_vgpu_pci_table);
+
+static struct pci_driver nvidia_vgpu_pci_driver = {
+	.name		= "nvidia-vgpu-vfio-pci",
+	.id_table	= nvidia_vgpu_pci_table,
+	.probe		= nvidia_vgpu_pci_probe,
+	.remove		= nvidia_vgpu_pci_remove,
+	.driver_managed_dma = true,
+};
+module_pci_driver(nvidia_vgpu_pci_driver);
+
+MODULE_DESCRIPTION("NVIDIA vGPU vfio-pci driver");
+MODULE_LICENSE("GPL");
+MODULE_IMPORT_NS("NOVA_CORE_VGPU");
-- 
2.53.0