[RFC PATCH 5/9] vfio-pci-core: add vfio_pci_mmap & helpers

[Mahmoud Adam <mngyadam@amazon.de>]

support the new vmmap solution to vfio-pci-core, this adds the
vfio_pci_mmap struct. the core already keeps the offset and size of
the region, extend it with bar_index.
Add alloc helper funciton for vfio_pci, which allocates and insert
vmmap to the mt, for the transitioning period the mtree_insert_range
is used with the same offset calculation as the legacy solution, so
that we don't break VFIO_PCI_OFFSET_TO_INDEX usages, eventually after
all the vfio_pci_devices are migrated to the new ops, these macros
will be replaced with mtree_load or similar, then maple tree
allocation could be used instead of direct insertions.

Signed-off-by: Mahmoud Adam <mngyadam@amazon.de>
---
 drivers/vfio/pci/vfio_pci_core.c | 44 ++++++++++++++++++++++++++++++++
 include/linux/vfio_pci_core.h    | 10 ++++++++
 2 files changed, 54 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 467466a0b619f..7a431a03bd850 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -882,6 +882,50 @@ static int msix_mmappable_cap(struct vfio_pci_core_device *vdev,
 	return vfio_info_add_capability(caps, &header, sizeof(header));
 }
 
+static void vfio_pci_mmap_free(struct vfio_mmap *core_vmmap)
+{
+	struct vfio_pci_mmap *vmmap = container_of(core_vmmap,
+						   struct vfio_pci_mmap,
+						   core);
+	kfree(vmmap);
+}
+
+static struct vfio_mmap_ops vfio_pci_mmap_ops = {
+	.free = vfio_pci_mmap_free,
+};
+
+int vfio_pci_mmap_alloc(struct vfio_pci_core_device *vdev,
+			struct maple_tree *mmap_mt, u32 region_flags,
+			size_t bar_size, unsigned int bar_index,
+			unsigned long *offset)
+{
+	struct vfio_pci_mmap *vmmap;
+	int ret;
+	unsigned long alloc_size;
+	vmmap = kzalloc(sizeof(*vmmap), GFP_KERNEL);
+	if (!vmmap)
+		return -ENOMEM;
+
+	alloc_size = PAGE_ALIGN(bar_size);
+	/* keep the offset aligned to the current usage for now, so we
+	 * don't break VFIO_PCI_OFFSET_TO_INDEX */
+	*offset = VFIO_PCI_INDEX_TO_OFFSET(bar_index);
+	vmmap->bar_index = bar_index;
+	vfio_mmap_init(&vdev->vdev, &vmmap->core, region_flags,
+		       *offset, alloc_size, &vfio_pci_mmap_ops);
+	ret = mtree_insert_range(mmap_mt, *offset,
+				 *offset + alloc_size - 1,
+				 &vmmap->core, GFP_KERNEL);
+	if (ret) {
+		vfio_mmap_free(&vmmap->core);
+		/* for now if it exists reuse it */
+		if (ret != -EEXIST)
+			return ret;
+	}
+	return 0;
+}
+EXPORT_SYMBOL(vfio_pci_mmap_alloc);
+
 int vfio_pci_core_register_dev_region(struct vfio_pci_core_device *vdev,
 				      unsigned int type, unsigned int subtype,
 				      const struct vfio_pci_regops *ops,
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index fbb472dd99b36..532d2914a9c2e 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -49,6 +49,11 @@ struct vfio_pci_region {
 	u32				flags;
 };
 
+struct vfio_pci_mmap {
+	struct vfio_mmap	core;
+	unsigned int		bar_index;
+};
+
 struct vfio_pci_core_device {
 	struct vfio_device	vdev;
 	struct pci_dev		*pdev;
@@ -137,6 +142,11 @@ bool vfio_pci_core_range_intersect_range(loff_t buf_start, size_t buf_cnt,
 					 loff_t *buf_offset,
 					 size_t *intersect_count,
 					 size_t *register_offset);
+int vfio_pci_mmap_alloc(struct vfio_pci_core_device *vdev,
+			struct maple_tree *mmap_mt, u32 region_flags,
+			size_t bar_size, unsigned int bar_index,
+			unsigned long *offset);
+
 #define VFIO_IOWRITE_DECLARATION(size) \
 int vfio_pci_core_iowrite##size(struct vfio_pci_core_device *vdev,	\
 			bool test_mem, u##size val, void __iomem *io);
-- 
2.47.3




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