[PATCH v2 13/20] vfio/cxl: CXL region management support

[<mhonap@nvidia.com>]

From: Manish Honap <mhonap@nvidia.com>

Region Management makes use of APIs provided by CXL_CORE as below:

CREATE_REGION flow:
1. Validate request (size, decoder availability)
2. Allocate HPA via cxl_get_hpa_freespace()
3. Allocate DPA via cxl_request_dpa()
4. Create region via cxl_create_region() - commits HDM decoder
5. Get HPA range via cxl_get_region_range()

DESTROY_REGION flow:
1. Detach decoder via cxl_decoder_detach()
2. Free DPA via cxl_dpa_free()
3. Release root decoder via cxl_put_root_decoder()

Use DEFINE_FREE scope helpers so error paths unwind cleanly.

Signed-off-by: Manish Honap <mhonap@nvidia.com>
---
 drivers/vfio/pci/cxl/vfio_cxl_core.c | 119 +++++++++++++++++++++++++++
 drivers/vfio/pci/cxl/vfio_cxl_priv.h |   8 ++
 2 files changed, 127 insertions(+)

diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c
index 02755265d530..30b365b91903 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_core.c
+++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c
@@ -21,6 +21,13 @@
 #include "../vfio_pci_priv.h"
 #include "vfio_cxl_priv.h"
 
+/*
+ * Scope-based cleanup wrappers for the CXL resource APIs
+ */
+DEFINE_FREE(cxl_put_root_decoder, struct cxl_root_decoder *, if (!IS_ERR_OR_NULL(_T)) cxl_put_root_decoder(_T))
+DEFINE_FREE(cxl_dpa_free, struct cxl_endpoint_decoder *, if (!IS_ERR_OR_NULL(_T)) cxl_dpa_free(_T))
+DEFINE_FREE(cxl_unregister_region, struct cxl_region *, if (!IS_ERR_OR_NULL(_T)) cxl_unregister_region(_T))
+
 /*
  * vfio_cxl_create_device_state - Allocate and validate CXL device state
  *
@@ -165,6 +172,112 @@ static int vfio_cxl_setup_regs(struct vfio_pci_core_device *vdev,
 	return ret;
 }
 
+int vfio_cxl_create_cxl_region(struct vfio_pci_cxl_state *cxl,
+			       resource_size_t size)
+{
+	resource_size_t max_size;
+
+	WARN_ON(cxl->precommitted);
+
+	struct cxl_root_decoder *cxlrd __free(cxl_put_root_decoder) =
+		cxl_get_hpa_freespace(cxl->cxlmd, 1,
+				      CXL_DECODER_F_RAM | CXL_DECODER_F_TYPE2,
+				      &max_size);
+	if (IS_ERR(cxlrd))
+		return PTR_ERR(cxlrd);
+
+	/* Insufficient HPA space; cxlrd freed automatically by __free() */
+	if (max_size < size)
+		return -ENOSPC;
+
+	struct cxl_endpoint_decoder *cxled __free(cxl_dpa_free) =
+		cxl_request_dpa(cxl->cxlmd, CXL_PARTMODE_RAM, size);
+	if (IS_ERR(cxled))
+		return PTR_ERR(cxled);
+
+	struct cxl_region *region __free(cxl_unregister_region) =
+		cxl_create_region(cxlrd, &cxled, 1);
+	if (IS_ERR(region))
+		return PTR_ERR(region);
+
+	/* All operations succeeded; transfer ownership to cxl state */
+	cxl->cxlrd  = no_free_ptr(cxlrd);
+	cxl->cxled  = no_free_ptr(cxled);
+	cxl->region = no_free_ptr(region);
+
+	return 0;
+}
+
+void vfio_cxl_destroy_cxl_region(struct vfio_pci_cxl_state *cxl)
+{
+	if (!cxl->region)
+		return;
+
+	cxl_unregister_region(cxl->region);
+	cxl->region = NULL;
+
+	if (!cxl->precommitted) {
+		cxl_dpa_free(cxl->cxled);
+		cxl_put_root_decoder(cxl->cxlrd);
+	}
+
+	cxl->cxled = NULL;
+	cxl->cxlrd = NULL;
+}
+
+static int vfio_cxl_create_region_helper(struct vfio_pci_core_device *vdev,
+					 struct vfio_pci_cxl_state *cxl,
+					 resource_size_t capacity)
+{
+	struct pci_dev *pdev = vdev->pdev;
+	struct range range;
+	int ret;
+
+	if (cxl->precommitted) {
+		struct cxl_endpoint_decoder *cxled;
+		struct cxl_region *region;
+
+		cxled = cxl_get_committed_decoder(cxl->cxlmd, &region);
+		if (IS_ERR(cxled))
+			return PTR_ERR(cxled);
+		cxl->cxled = cxled;
+		cxl->region = region;
+	} else {
+		ret = vfio_cxl_create_cxl_region(cxl, capacity);
+		if (ret)
+			return ret;
+	}
+
+	if (!cxl->region) {
+		pci_err(pdev, "Failed to create CXL region\n");
+		ret = -ENODEV;
+		goto failed;
+	}
+
+	ret = cxl_get_region_range(cxl->region, &range);
+	if (ret)
+		goto failed;
+
+	cxl->region_hpa = range.start;
+	cxl->region_size = range_len(&range);
+
+	pci_dbg(pdev, "CXL region: HPA 0x%llx size %lu MB\n",
+		cxl->region_hpa, cxl->region_size >> 20);
+
+	return 0;
+
+failed:
+	if (cxl->region) {
+		cxl_unregister_region(cxl->region);
+		cxl->region = NULL;
+	}
+
+	cxl->cxled = NULL;
+	cxl->cxlrd = NULL;
+
+	return ret;
+}
+
 static int vfio_cxl_create_memdev(struct vfio_pci_cxl_state *cxl,
 				  resource_size_t capacity)
 {
@@ -279,6 +392,7 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 		goto regs_failed;
 	}
 
+	cxl->precommitted = true;
 	cxl->dpa_size = capacity;
 
 	pci_dbg(pdev, "Device capacity: %llu MB\n", capacity >> 20);
@@ -289,6 +403,10 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 		goto regs_failed;
 	}
 
+	ret = vfio_cxl_create_region_helper(vdev, cxl, capacity);
+	if (ret)
+		goto regs_failed;
+
 	/*
 	 * Register probing succeeded.  Assign vdev->cxl now so that
 	 * all subsequent helpers can access state via vdev->cxl.
@@ -314,6 +432,7 @@ void vfio_pci_cxl_cleanup(struct vfio_pci_core_device *vdev)
 		return;
 
 	vfio_cxl_clean_virt_regs(cxl);
+	vfio_cxl_destroy_cxl_region(cxl);
 }
 
 MODULE_IMPORT_NS("CXL");
diff --git a/drivers/vfio/pci/cxl/vfio_cxl_priv.h b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
index 6359ad260bde..72a0d7d7e183 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_priv.h
+++ b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
@@ -17,6 +17,10 @@ struct vfio_pci_cxl_state {
 	struct cxl_memdev           *cxlmd;
 	struct cxl_root_decoder     *cxlrd;
 	struct cxl_endpoint_decoder *cxled;
+	struct cxl_region	    *region;
+	resource_size_t		     region_hpa;
+	size_t			     region_size;
+	void			    *region_vaddr;
 	resource_size_t              hdm_reg_offset;
 	size_t                       hdm_reg_size;
 	resource_size_t              comp_reg_offset;
@@ -28,6 +32,7 @@ struct vfio_pci_cxl_state {
 	u8                           hdm_count;
 	u8                           comp_reg_bar;
 	bool                         cache_capable;
+	bool                         precommitted;
 };
 
 /* Register access sizes */
@@ -87,5 +92,8 @@ void vfio_cxl_reinit_comp_regs(struct vfio_pci_cxl_state *cxl);
 resource_size_t
 vfio_cxl_read_committed_decoder_size(struct vfio_pci_core_device *vdev,
 				     struct vfio_pci_cxl_state *cxl);
+int vfio_cxl_create_cxl_region(struct vfio_pci_cxl_state *cxl,
+			       resource_size_t size);
+void vfio_cxl_destroy_cxl_region(struct vfio_pci_cxl_state *cxl);
 
 #endif /* __LINUX_VFIO_CXL_PRIV_H */
-- 
2.25.1