[PATCH] vfio/cdx: add support for CDX bus

[Nipun Gupta]

vfio-cdx driver enables IOCTLs for user space to query
MMIO regions for CDX devices and mmap them. This change
also adds support for reset of CDX devices.

This change adds the VFIO CDX driver and enables the following
ioctls for CDX devices:
 - VFIO_DEVICE_GET_INFO:
 - VFIO_DEVICE_GET_REGION_INFO
 - VFIO_DEVICE_RESET

Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@xxxxxxx>
Tested-by: Nikhil Agarwal <nikhil.agarwal@xxxxxxx>
---

CDX bus is now merged on linux-next tree. So sending VFIO driver
patch for CDX bus.

 MAINTAINERS                         |   1 +
 drivers/vfio/Kconfig                |   1 +
 drivers/vfio/Makefile               |   1 +
 drivers/vfio/cdx/Kconfig            |  17 ++
 drivers/vfio/cdx/Makefile           |   8 +
 drivers/vfio/cdx/vfio_cdx.c         | 314 ++++++++++++++++++++++++++++
 drivers/vfio/cdx/vfio_cdx_private.h |  32 +++
 7 files changed, 374 insertions(+)
 create mode 100644 drivers/vfio/cdx/Kconfig
 create mode 100644 drivers/vfio/cdx/Makefile
 create mode 100644 drivers/vfio/cdx/vfio_cdx.c
 create mode 100644 drivers/vfio/cdx/vfio_cdx_private.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 99b665e85f0a..2acb3dbff174 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -970,6 +970,7 @@ M:	Nikhil Agarwal <nikhil.agarwal@xxxxxxx>
 S:	Maintained
 F:	Documentation/devicetree/bindings/bus/xlnx,versal-net-cdx.yaml
 F:	drivers/cdx/*
+F:	drivers/vfio/cdx/*
 F:	include/linux/cdx/*
 
 AMD CRYPTOGRAPHIC COPROCESSOR (CCP) DRIVER
diff --git a/drivers/vfio/Kconfig b/drivers/vfio/Kconfig
index 89e06c981e43..aba36f5be4ec 100644
--- a/drivers/vfio/Kconfig
+++ b/drivers/vfio/Kconfig
@@ -57,6 +57,7 @@ source "drivers/vfio/pci/Kconfig"
 source "drivers/vfio/platform/Kconfig"
 source "drivers/vfio/mdev/Kconfig"
 source "drivers/vfio/fsl-mc/Kconfig"
+source "drivers/vfio/cdx/Kconfig"
 endif
 
 source "virt/lib/Kconfig"
diff --git a/drivers/vfio/Makefile b/drivers/vfio/Makefile
index 70e7dcb302ef..1a27b2516612 100644
--- a/drivers/vfio/Makefile
+++ b/drivers/vfio/Makefile
@@ -14,3 +14,4 @@ obj-$(CONFIG_VFIO_PCI) += pci/
 obj-$(CONFIG_VFIO_PLATFORM) += platform/
 obj-$(CONFIG_VFIO_MDEV) += mdev/
 obj-$(CONFIG_VFIO_FSL_MC) += fsl-mc/
+obj-$(CONFIG_VFIO_CDX) += cdx/
diff --git a/drivers/vfio/cdx/Kconfig b/drivers/vfio/cdx/Kconfig
new file mode 100644
index 000000000000..e6de0a0caa32
--- /dev/null
+++ b/drivers/vfio/cdx/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# VFIO CDX configuration
+#
+# Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+#
+
+config VFIO_CDX
+	tristate "VFIO support for CDX bus devices"
+	depends on CDX_BUS
+	select EVENTFD
+	help
+	  Driver to enable VFIO support for the devices on CDX bus.
+	  This is required to make use of CDX devices present in
+	  the system using the VFIO framework.
+
+	  If you don't know what to do here, say N.
diff --git a/drivers/vfio/cdx/Makefile b/drivers/vfio/cdx/Makefile
new file mode 100644
index 000000000000..82e4ef412c0f
--- /dev/null
+++ b/drivers/vfio/cdx/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+#
+
+obj-$(CONFIG_VFIO_CDX) += vfio-cdx.o
+
+vfio-cdx-objs := vfio_cdx.o
diff --git a/drivers/vfio/cdx/vfio_cdx.c b/drivers/vfio/cdx/vfio_cdx.c
new file mode 100644
index 000000000000..c23be3e06495
--- /dev/null
+++ b/drivers/vfio/cdx/vfio_cdx.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#include <linux/device.h>
+#include <linux/iommu.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/vfio.h>
+#include <linux/cdx/cdx_bus.h>
+#include <linux/delay.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
+
+#include "vfio_cdx_private.h"
+
+static struct cdx_driver vfio_cdx_driver;
+
+enum {
+	CDX_ID_F_VFIO_DRIVER_OVERRIDE = 1,
+};
+
+static int vfio_cdx_init_device(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+	struct cdx_device *cdx_dev = to_cdx_device(core_vdev->dev);
+
+	vdev->cdx_dev = cdx_dev;
+	vdev->dev = &cdx_dev->dev;
+
+	return 0;
+}
+
+static void vfio_cdx_release_device(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+
+	vdev->cdx_dev = NULL;
+	vdev->dev = NULL;
+}
+
+/**
+ * CDX_DRIVER_OVERRIDE_DEVICE_VFIO - macro used to describe a VFIO
+ *                                   "driver_override" CDX device.
+ * @vend: the 16 bit CDX Vendor ID
+ * @dev: the 16 bit CDX Device ID
+ *
+ * This macro is used to create a struct cdx_device_id that matches a
+ * specific device. driver_override will be set to
+ * CDX_ID_F_VFIO_DRIVER_OVERRIDE.
+ */
+#define CDX_DRIVER_OVERRIDE_DEVICE_VFIO(vend, dev) \
+	CDX_DEVICE_DRIVER_OVERRIDE(vend, dev, CDX_ID_F_VFIO_DRIVER_OVERRIDE)
+
+static int vfio_cdx_open_device(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+	struct cdx_device *cdx_dev = vdev->cdx_dev;
+	int count = cdx_dev->res_count;
+	int i;
+
+	vdev->regions = kcalloc(count, sizeof(struct vfio_cdx_region),
+				GFP_KERNEL);
+	if (!vdev->regions)
+		return -ENOMEM;
+
+	for (i = 0; i < count; i++) {
+		struct resource *res = &cdx_dev->res[i];
+
+		vdev->regions[i].addr = res->start;
+		vdev->regions[i].size = resource_size(res);
+		vdev->regions[i].type = res->flags;
+		/*
+		 * Only regions addressed with PAGE granularity may be
+		 * MMAP'ed securely.
+		 */
+		if (!(vdev->regions[i].addr & ~PAGE_MASK) &&
+		    !(vdev->regions[i].size & ~PAGE_MASK))
+			vdev->regions[i].flags |=
+					VFIO_REGION_INFO_FLAG_MMAP;
+		vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_READ;
+		if (!(cdx_dev->res[i].flags & IORESOURCE_READONLY))
+			vdev->regions[i].flags |= VFIO_REGION_INFO_FLAG_WRITE;
+	}
+
+	return 0;
+}
+
+static void vfio_cdx_regions_cleanup(struct vfio_cdx_device *vdev)
+{
+	kfree(vdev->regions);
+}
+
+static int vfio_cdx_reset_device(struct vfio_cdx_device *vdev)
+{
+	return cdx_dev_reset(&vdev->cdx_dev->dev);
+}
+
+static void vfio_cdx_close_device(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+	int ret;
+
+	vfio_cdx_regions_cleanup(vdev);
+
+	/* reset the device before cleaning up the interrupts */
+	ret = vfio_cdx_reset_device(vdev);
+	if (WARN_ON(ret))
+		dev_warn(core_vdev->dev,
+			 "VFIO_CDX: reset device has failed (%d)\n", ret);
+}
+
+static long vfio_cdx_ioctl(struct vfio_device *core_vdev,
+			   unsigned int cmd, unsigned long arg)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+	struct cdx_device *cdx_dev = vdev->cdx_dev;
+	unsigned long minsz;
+
+	switch (cmd) {
+	case VFIO_DEVICE_GET_INFO:
+	{
+		struct vfio_device_info info;
+
+		minsz = offsetofend(struct vfio_device_info, num_irqs);
+
+		if (copy_from_user(&info, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (info.argsz < minsz)
+			return -EINVAL;
+
+		info.flags = VFIO_DEVICE_FLAGS_RESET;
+
+		info.num_regions = cdx_dev->res_count;
+		info.num_irqs = 0;
+
+		return copy_to_user((void __user *)arg, &info, minsz) ?
+			-EFAULT : 0;
+	}
+	case VFIO_DEVICE_GET_REGION_INFO:
+	{
+		struct vfio_region_info info;
+
+		minsz = offsetofend(struct vfio_region_info, offset);
+
+		if (copy_from_user(&info, (void __user *)arg, minsz))
+			return -EFAULT;
+
+		if (info.argsz < minsz)
+			return -EINVAL;
+
+		if (info.index >= cdx_dev->res_count)
+			return -EINVAL;
+
+		/* map offset to the physical address  */
+		info.offset = VFIO_CDX_INDEX_TO_OFFSET(info.index);
+		info.size = vdev->regions[info.index].size;
+		info.flags = vdev->regions[info.index].flags;
+
+		if (copy_to_user((void __user *)arg, &info, minsz))
+			return -EFAULT;
+		return 0;
+	}
+	case VFIO_DEVICE_RESET:
+	{
+		return vfio_cdx_reset_device(vdev);
+	}
+	default:
+		return -ENOTTY;
+	}
+}
+
+static int vfio_cdx_mmap_mmio(struct vfio_cdx_region region,
+			      struct vm_area_struct *vma)
+{
+	u64 size = vma->vm_end - vma->vm_start;
+	u64 pgoff, base;
+
+	pgoff = vma->vm_pgoff &
+		((1U << (VFIO_CDX_OFFSET_SHIFT - PAGE_SHIFT)) - 1);
+	base = pgoff << PAGE_SHIFT;
+
+	if (region.size < PAGE_SIZE || base + size > region.size)
+		return -EINVAL;
+
+	vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff;
+	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
+
+	return remap_pfn_range(vma, vma->vm_start, vma->vm_pgoff,
+			       size, vma->vm_page_prot);
+}
+
+static int vfio_cdx_mmap(struct vfio_device *core_vdev,
+			 struct vm_area_struct *vma)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+	struct cdx_device *cdx_dev = vdev->cdx_dev;
+	unsigned int index;
+
+	index = vma->vm_pgoff >> (VFIO_CDX_OFFSET_SHIFT - PAGE_SHIFT);
+
+	if (vma->vm_end < vma->vm_start)
+		return -EINVAL;
+	if (vma->vm_start & ~PAGE_MASK)
+		return -EINVAL;
+	if (vma->vm_end & ~PAGE_MASK)
+		return -EINVAL;
+	if (!(vma->vm_flags & VM_SHARED))
+		return -EINVAL;
+	if (index >= cdx_dev->res_count)
+		return -EINVAL;
+
+	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_MMAP))
+		return -EINVAL;
+
+	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_READ) &&
+	    (vma->vm_flags & VM_READ))
+		return -EINVAL;
+
+	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_WRITE) &&
+	    (vma->vm_flags & VM_WRITE))
+		return -EINVAL;
+
+	vma->vm_private_data = cdx_dev;
+
+	return vfio_cdx_mmap_mmio(vdev->regions[index], vma);
+}
+
+static const struct vfio_device_ops vfio_cdx_ops = {
+	.name		= "vfio-cdx",
+	.init		= vfio_cdx_init_device,
+	.release	= vfio_cdx_release_device,
+	.open_device	= vfio_cdx_open_device,
+	.close_device	= vfio_cdx_close_device,
+	.ioctl		= vfio_cdx_ioctl,
+	.mmap		= vfio_cdx_mmap,
+};
+
+static int vfio_cdx_probe(struct cdx_device *cdx_dev)
+{
+	struct vfio_cdx_device *vdev = NULL;
+	struct device *dev = &cdx_dev->dev;
+	int ret;
+
+	vdev = vfio_alloc_device(vfio_cdx_device, vdev, dev,
+				 &vfio_cdx_ops);
+	if (IS_ERR(vdev))
+		return PTR_ERR(vdev);
+
+	ret = vfio_register_group_dev(&vdev->vdev);
+	if (ret) {
+		dev_err(dev, "VFIO_CDX: Failed to add to vfio group\n");
+		goto out_uninit;
+	}
+
+	dev_set_drvdata(dev, vdev);
+	return 0;
+
+out_uninit:
+	vfio_put_device(&vdev->vdev);
+	return ret;
+}
+
+static int vfio_cdx_remove(struct cdx_device *cdx_dev)
+{
+	struct device *dev = &cdx_dev->dev;
+	struct vfio_cdx_device *vdev;
+
+	vdev = dev_get_drvdata(dev);
+	vfio_unregister_group_dev(&vdev->vdev);
+	vfio_put_device(&vdev->vdev);
+
+	return 0;
+}
+
+static const struct cdx_device_id vfio_cdx_table[] = {
+	{ CDX_DRIVER_OVERRIDE_DEVICE_VFIO(CDX_ANY_ID, CDX_ANY_ID) }, /* match all by default */
+	{}
+};
+
+static struct cdx_driver vfio_cdx_driver = {
+	.probe		= vfio_cdx_probe,
+	.remove		= vfio_cdx_remove,
+	.match_id_table	= vfio_cdx_table,
+	.driver	= {
+		.name	= "vfio-cdx",
+		.owner	= THIS_MODULE,
+	},
+	.driver_managed_dma = true,
+};
+
+static int __init vfio_cdx_driver_init(void)
+{
+	return cdx_driver_register(&vfio_cdx_driver);
+}
+
+static void __exit vfio_cdx_driver_exit(void)
+{
+	cdx_driver_unregister(&vfio_cdx_driver);
+}
+
+module_init(vfio_cdx_driver_init);
+module_exit(vfio_cdx_driver_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("VFIO for CDX devices - User Level meta-driver");
diff --git a/drivers/vfio/cdx/vfio_cdx_private.h b/drivers/vfio/cdx/vfio_cdx_private.h
new file mode 100644
index 000000000000..8b6f1ee3f5cd
--- /dev/null
+++ b/drivers/vfio/cdx/vfio_cdx_private.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#ifndef VFIO_CDX_PRIVATE_H
+#define VFIO_CDX_PRIVATE_H
+
+#define VFIO_CDX_OFFSET_SHIFT    40
+#define VFIO_CDX_OFFSET_MASK (((u64)(1) << VFIO_CDX_OFFSET_SHIFT) - 1)
+
+#define VFIO_CDX_OFFSET_TO_INDEX(off) ((off) >> VFIO_CDX_OFFSET_SHIFT)
+
+#define VFIO_CDX_INDEX_TO_OFFSET(index)	\
+	((u64)(index) << VFIO_CDX_OFFSET_SHIFT)
+
+struct vfio_cdx_region {
+	u32			flags;
+	u32			type;
+	u64			addr;
+	resource_size_t		size;
+	void __iomem		*ioaddr;
+};
+
+struct vfio_cdx_device {
+	struct vfio_device	vdev;
+	struct cdx_device	*cdx_dev;
+	struct device		*dev;
+	struct vfio_cdx_region	*regions;
+};
+
+#endif /* VFIO_CDX_PRIVATE_H */
-- 
2.17.1