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Subject: [PATCH v1 06/14] vfio: Add vma to pfn callback
From:   Alex Williamson <alex.williamson@redhat.com>
To:     alex.williamson@redhat.com
Cc:     cohuck@redhat.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, jgg@nvidia.com, peterx@redhat.com
Date:   Mon, 08 Mar 2021 14:48:16 -0700
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In-Reply-To: <161523878883.3480.12103845207889888280.stgit@gimli.home>
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Add a new vfio_device_ops callback to allow the bus driver to
translate a vma mapping of a vfio device fd to a pfn.  Plumb through
vfio-core.  Implemented for vfio-pci.

Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
 drivers/vfio/pci/vfio_pci.c |    1 +
 drivers/vfio/vfio.c         |   16 ++++++++++++++++
 include/linux/vfio.h        |    3 +++
 3 files changed, 20 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 415b5109da9b..585895970e9c 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -1756,6 +1756,7 @@ static const struct vfio_device_ops vfio_pci_ops = {
 	.mmap		= vfio_pci_mmap,
 	.request	= vfio_pci_request,
 	.match		= vfio_pci_match,
+	.vma_to_pfn	= vfio_pci_bar_vma_to_pfn,
 };
 
 static int vfio_pci_reflck_attach(struct vfio_pci_device *vdev);
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index 3a3e85a0dc3e..c47895539a1a 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -944,6 +944,22 @@ struct vfio_device *vfio_device_get_from_vma(struct vm_area_struct *vma)
 }
 EXPORT_SYMBOL_GPL(vfio_device_get_from_vma);
 
+int vfio_vma_to_pfn(struct vm_area_struct *vma, unsigned long *pfn)
+{
+	struct vfio_device *device;
+
+	if (!vma->vm_file || vma->vm_file->f_op != &vfio_device_fops)
+		return -EINVAL;
+
+	device = vma->vm_file->private_data;
+
+	if (unlikely(!device->ops->vma_to_pfn))
+		return -EINVAL;
+
+	return device->ops->vma_to_pfn(vma, pfn);
+}
+EXPORT_SYMBOL_GPL(vfio_vma_to_pfn);
+
 static struct vfio_device *vfio_device_get_from_name(struct vfio_group *group,
 						     char *buf)
 {
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 660b8adf90a6..dbd90d0ba713 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -29,6 +29,7 @@
  * @match: Optional device name match callback (return: 0 for no-match, >0 for
  *         match, -errno for abort (ex. match with insufficient or incorrect
  *         additional args)
+ * @vma_to_pfn: Optional pfn from vma lookup against vma mapping device fd
  */
 struct vfio_device_ops {
 	char	*name;
@@ -43,6 +44,7 @@ struct vfio_device_ops {
 	int	(*mmap)(void *device_data, struct vm_area_struct *vma);
 	void	(*request)(void *device_data, unsigned int count);
 	int	(*match)(void *device_data, char *buf);
+	int	(*vma_to_pfn)(struct vm_area_struct *vma, unsigned long *pfn);
 };
 
 extern struct iommu_group *vfio_iommu_group_get(struct device *dev);
@@ -59,6 +61,7 @@ extern void *vfio_device_data(struct vfio_device *device);
 extern void vfio_device_unmap_mapping_range(struct vfio_device *device,
 					    loff_t start, loff_t len);
 extern struct vfio_device *vfio_device_get_from_vma(struct vm_area_struct *vma);
+extern int vfio_vma_to_pfn(struct vm_area_struct *vma, unsigned long *pfn);
 
 /* events for the backend driver notify callback */
 enum vfio_iommu_notify_type {