vfio/cdx: add support for CDX bus

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. With VFIO
enabled on CDX devices, user-space applications can also
exercise DMA securely via IOMMU on these 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@amd.com>
Reviewed-by: Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>
Tested-by: Nikhil Agarwal <nikhil.agarwal@amd.com>
Link: https://lore.kernel.org/r/20230531124557.11009-1-nipun.gupta@amd.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>

MAINTAINERS

@@ -22085,6 +22085,13 @@ F:	Documentation/filesystems/vfat.rst
 F:	fs/fat/
 F:	tools/testing/selftests/filesystems/fat/
 
+VFIO CDX DRIVER
+M:	Nipun Gupta <nipun.gupta@amd.com>
+M:	Nikhil Agarwal <nikhil.agarwal@amd.com>
+L:	kvm@vger.kernel.org
+S:	Maintained
+F:	drivers/vfio/cdx/*
+
 VFIO DRIVER
 M:	Alex Williamson <alex.williamson@redhat.com>
 L:	kvm@vger.kernel.org

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"

drivers/vfio/Makefile

@@ -14,3 +14,4 @@ obj-$(CONFIG_VFIO_PCI_CORE) += pci/
 obj-$(CONFIG_VFIO_PLATFORM_BASE) += platform/
 obj-$(CONFIG_VFIO_MDEV) += mdev/
 obj-$(CONFIG_VFIO_FSL_MC) += fsl-mc/
+obj-$(CONFIG_VFIO_CDX) += cdx/

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.

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 := main.o

drivers/vfio/cdx/main.c

@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#include <linux/vfio.h>
+#include <linux/cdx/cdx_bus.h>
+
+#include "private.h"
+
+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 = to_cdx_device(core_vdev->dev);
+	int count = cdx_dev->res_count;
+	int i;
+
+	vdev->regions = kcalloc(count, sizeof(struct vfio_cdx_region),
+				GFP_KERNEL_ACCOUNT);
+	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_close_device(struct vfio_device *core_vdev)
+{
+	struct vfio_cdx_device *vdev =
+		container_of(core_vdev, struct vfio_cdx_device, vdev);
+
+	kfree(vdev->regions);
+	cdx_dev_reset(core_vdev->dev);
+}
+
+static int vfio_cdx_ioctl_get_info(struct vfio_cdx_device *vdev,
+				   struct vfio_device_info __user *arg)
+{
+	unsigned long minsz = offsetofend(struct vfio_device_info, num_irqs);
+	struct cdx_device *cdx_dev = to_cdx_device(vdev->vdev.dev);
+	struct vfio_device_info info;
+
+	if (copy_from_user(&info, arg, minsz))
+		return -EFAULT;
+
+	if (info.argsz < minsz)
+		return -EINVAL;
+
+	info.flags = VFIO_DEVICE_FLAGS_CDX;
+	info.flags |= VFIO_DEVICE_FLAGS_RESET;
+
+	info.num_regions = cdx_dev->res_count;
+	info.num_irqs = 0;
+
+	return copy_to_user(arg, &info, minsz) ? -EFAULT : 0;
+}
+
+static int vfio_cdx_ioctl_get_region_info(struct vfio_cdx_device *vdev,
+					  struct vfio_region_info __user *arg)
+{
+	unsigned long minsz = offsetofend(struct vfio_region_info, offset);
+	struct cdx_device *cdx_dev = to_cdx_device(vdev->vdev.dev);
+	struct vfio_region_info info;
+
+	if (copy_from_user(&info, 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;
+
+	return copy_to_user(arg, &info, minsz) ? -EFAULT : 0;
+}
+
+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);
+	void __user *uarg = (void __user *)arg;
+
+	switch (cmd) {
+	case VFIO_DEVICE_GET_INFO:
+		return vfio_cdx_ioctl_get_info(vdev, uarg);
+	case VFIO_DEVICE_GET_REGION_INFO:
+		return vfio_cdx_ioctl_get_region_info(vdev, uarg);
+	case VFIO_DEVICE_RESET:
+		return cdx_dev_reset(core_vdev->dev);
+	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 (base + size > region.size)
+		return -EINVAL;
+
+	vma->vm_pgoff = (region.addr >> PAGE_SHIFT) + pgoff;
+	vma->vm_page_prot = pgprot_device(vma->vm_page_prot);
+
+	return io_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 = to_cdx_device(core_vdev->dev);
+	unsigned int index;
+
+	index = vma->vm_pgoff >> (VFIO_CDX_OFFSET_SHIFT - PAGE_SHIFT);
+
+	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 -EPERM;
+
+	if (!(vdev->regions[index].flags & VFIO_REGION_INFO_FLAG_WRITE) &&
+	    (vma->vm_flags & VM_WRITE))
+		return -EPERM;
+
+	return vfio_cdx_mmap_mmio(vdev->regions[index], vma);
+}
+
+static const struct vfio_device_ops vfio_cdx_ops = {
+	.name		= "vfio-cdx",
+	.open_device	= vfio_cdx_open_device,
+	.close_device	= vfio_cdx_close_device,
+	.ioctl		= vfio_cdx_ioctl,
+	.mmap		= vfio_cdx_mmap,
+	.bind_iommufd	= vfio_iommufd_physical_bind,
+	.unbind_iommufd	= vfio_iommufd_physical_unbind,
+	.attach_ioas	= vfio_iommufd_physical_attach_ioas,
+};
+
+static int vfio_cdx_probe(struct cdx_device *cdx_dev)
+{
+	struct vfio_cdx_device *vdev;
+	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)
+		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 = 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_DEVICE_DRIVER_OVERRIDE(CDX_ANY_ID, CDX_ANY_ID,
+				     CDX_ID_F_VFIO_DRIVER_OVERRIDE) }, /* match all by default */
+	{}
+};
+
+MODULE_DEVICE_TABLE(cdx, vfio_cdx_table);
+
+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,
+};
+
+module_driver(vfio_cdx_driver, cdx_driver_register, cdx_driver_unregister);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("VFIO for CDX devices - User Level meta-driver");

drivers/vfio/cdx/private.h

@@ -0,0 +1,28 @@
+/* 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
+
+static inline u64 vfio_cdx_index_to_offset(u32 index)
+{
+	return ((u64)(index) << VFIO_CDX_OFFSET_SHIFT);
+}
+
+struct vfio_cdx_region {
+	u32			flags;
+	u32			type;
+	u64			addr;
+	resource_size_t		size;
+};
+
+struct vfio_cdx_device {
+	struct vfio_device	vdev;
+	struct vfio_cdx_region	*regions;
+};
+
+#endif /* VFIO_CDX_PRIVATE_H */

include/linux/cdx/cdx_bus.h

@@ -14,7 +14,6 @@
 #include <linux/mod_devicetable.h>
 
 #define MAX_CDX_DEV_RESOURCES	4
-#define CDX_ANY_ID (0xFFFF)
 #define CDX_CONTROLLER_ID_SHIFT 4
 #define CDX_BUS_NUM_MASK 0xF
 

include/linux/mod_devicetable.h

@@ -912,6 +912,12 @@ struct ishtp_device_id {
 	kernel_ulong_t driver_data;
 };
 
+#define CDX_ANY_ID (0xFFFF)
+
+enum {
+	CDX_ID_F_VFIO_DRIVER_OVERRIDE = 1,
+};
+
 /**
  * struct cdx_device_id - CDX device identifier
  * @vendor: Vendor ID

include/uapi/linux/vfio.h

@@ -213,6 +213,7 @@ struct vfio_device_info {
 #define VFIO_DEVICE_FLAGS_AP	(1 << 5)	/* vfio-ap device */
 #define VFIO_DEVICE_FLAGS_FSL_MC (1 << 6)	/* vfio-fsl-mc device */
 #define VFIO_DEVICE_FLAGS_CAPS	(1 << 7)	/* Info supports caps */
+#define VFIO_DEVICE_FLAGS_CDX	(1 << 8)	/* vfio-cdx device */
 	__u32	num_regions;	/* Max region index + 1 */
 	__u32	num_irqs;	/* Max IRQ index + 1 */
 	__u32   cap_offset;	/* Offset within info struct of first cap */

scripts/mod/devicetable-offsets.c

@@ -265,6 +265,7 @@ int main(void)
 	DEVID(cdx_device_id);
 	DEVID_FIELD(cdx_device_id, vendor);
 	DEVID_FIELD(cdx_device_id, device);
+	DEVID_FIELD(cdx_device_id, override_only);
 
 	return 0;
 }

scripts/mod/file2alias.c

@@ -1458,8 +1458,23 @@ static int do_cdx_entry(const char *filename, void *symval,
 {
 	DEF_FIELD(symval, cdx_device_id, vendor);
 	DEF_FIELD(symval, cdx_device_id, device);
+	DEF_FIELD(symval, cdx_device_id, override_only);
 
-	sprintf(alias, "cdx:v%08Xd%08Xd", vendor, device);
+	switch (override_only) {
+	case 0:
+		strcpy(alias, "cdx:");
+		break;
+	case CDX_ID_F_VFIO_DRIVER_OVERRIDE:
+		strcpy(alias, "vfio_cdx:");
+		break;
+	default:
+		warn("Unknown CDX driver_override alias %08X\n",
+		     override_only);
+		return 0;
+	}
+
+	ADD(alias, "v", vendor != CDX_ANY_ID, vendor);
+	ADD(alias, "d", device != CDX_ANY_ID, device);
 	return 1;
 }