[PATCH v2 07/20] vfio/pci: Add CXL state to vfio_pci_core_device

[<mhonap@nvidia.com>]

From: Manish Honap <mhonap@nvidia.com>

Add CXL-specific state to vfio_pci_core_device structure to support
CXL Type-2 device passthrough.

The new vfio_pci_cxl_state structure embeds CXL core objects:
- struct cxl_dev_state: CXL device state (from CXL core)
- struct cxl_memdev: CXL memory device
- struct cxl_region: CXL region object
- Root and endpoint decoders

Key design point: The CXL state pointer is NULL for non-CXL devices,
allowing vfio-pci-core to handle both CXL and standard PCI devices
with minimal overhead.

This will follow the approach where vfio-pci-core itself gains CXL
awareness, rather than requiring a separate variant driver.

Signed-off-by: Manish Honap <mhonap@nvidia.com>
---
 drivers/vfio/pci/cxl/vfio_cxl_priv.h | 28 ++++++++++++++++++++++++++++
 include/linux/vfio_pci_core.h        |  3 +++
 2 files changed, 31 insertions(+)
 create mode 100644 drivers/vfio/pci/cxl/vfio_cxl_priv.h

diff --git a/drivers/vfio/pci/cxl/vfio_cxl_priv.h b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
new file mode 100644
index 000000000000..4cecc25db410
--- /dev/null
+++ b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Common infrastructure for CXL Type-2 device variant drivers
+ *
+ * Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved
+ */
+
+#ifndef __LINUX_VFIO_CXL_PRIV_H
+#define __LINUX_VFIO_CXL_PRIV_H
+
+#include <cxl/cxl.h>
+#include <linux/types.h>
+
+/* CXL device state embedded in vfio_pci_core_device */
+struct vfio_pci_cxl_state {
+	struct cxl_dev_state         cxlds;
+	struct cxl_memdev           *cxlmd;
+	struct cxl_root_decoder     *cxlrd;
+	struct cxl_endpoint_decoder *cxled;
+	resource_size_t              hdm_reg_offset;
+	size_t                       hdm_reg_size;
+	resource_size_t              comp_reg_offset;
+	size_t                       comp_reg_size;
+	u8                           hdm_count;
+	u8                           comp_reg_bar;
+};
+
+#endif /* __LINUX_VFIO_CXL_PRIV_H */
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 1ac86896875c..cd8ed98a82a3 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -30,6 +30,8 @@ struct vfio_pci_region;
 struct p2pdma_provider;
 struct dma_buf_phys_vec;
 struct dma_buf_attachment;
+struct vfio_pci_cxl_state;
+
 
 struct vfio_pci_eventfd {
 	struct eventfd_ctx	*ctx;
@@ -138,6 +140,7 @@ struct vfio_pci_core_device {
 	struct mutex		ioeventfds_lock;
 	struct list_head	ioeventfds_list;
 	struct vfio_pci_vf_token	*vf_token;
+	struct vfio_pci_cxl_state *cxl;
 	struct list_head		sriov_pfs_item;
 	struct vfio_pci_core_device	*sriov_pf_core_dev;
 	struct notifier_block	nb;
-- 
2.25.1