[PATCH 10/20] vfio/cxl: CXL region management

[<mhonap@nvidia.com>]

From: Manish Honap <mhonap@nvidia.com>

Add CXL region management for future guest access.

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()

Signed-off-by: Manish Honap <mhonap@nvidia.com>
---
 drivers/vfio/pci/cxl/vfio_cxl_core.c | 118 ++++++++++++++++++++++++++-
 drivers/vfio/pci/cxl/vfio_cxl_priv.h |   5 ++
 drivers/vfio/pci/vfio_pci_priv.h     |   8 ++
 3 files changed, 130 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/cxl/vfio_cxl_core.c b/drivers/vfio/pci/cxl/vfio_cxl_core.c
index 2da6da1c0605..9c71f592e74e 100644
--- a/drivers/vfio/pci/cxl/vfio_cxl_core.c
+++ b/drivers/vfio/pci/cxl/vfio_cxl_core.c
@@ -126,6 +126,112 @@ static int vfio_cxl_setup_regs(struct vfio_pci_core_device *vdev)
 	return 0;
 }
 
+int vfio_cxl_create_cxl_region(struct vfio_pci_core_device *vdev, resource_size_t size)
+{
+	struct vfio_pci_cxl_state *cxl = vdev->cxl;
+	resource_size_t max_size;
+	int ret;
+
+	if (cxl->precommitted)
+		return 0;
+
+	cxl->cxlrd = cxl_get_hpa_freespace(cxl->cxlmd, 1,
+					   CXL_DECODER_F_RAM |
+					   CXL_DECODER_F_TYPE2,
+					   &max_size);
+	if (IS_ERR(cxl->cxlrd))
+		return PTR_ERR(cxl->cxlrd);
+
+	/* Insufficient HPA space */
+	if (max_size < size) {
+		cxl_put_root_decoder(cxl->cxlrd);
+		cxl->cxlrd = NULL;
+		return -ENOSPC;
+	}
+
+	cxl->cxled = cxl_request_dpa(cxl->cxlmd, CXL_PARTMODE_RAM, size);
+	if (IS_ERR(cxl->cxled)) {
+		ret = PTR_ERR(cxl->cxled);
+		goto err_free_hpa;
+	}
+
+	cxl->region = cxl_create_region(cxl->cxlrd, &cxl->cxled, 1);
+	if (IS_ERR(cxl->region)) {
+		ret = PTR_ERR(cxl->region);
+		goto err_free_dpa;
+	}
+
+	return 0;
+
+err_free_dpa:
+	cxl_dpa_free(cxl->cxled);
+err_free_hpa:
+	if (cxl->cxlrd)
+		cxl_put_root_decoder(cxl->cxlrd);
+
+	return ret;
+}
+
+void vfio_cxl_destroy_cxl_region(struct vfio_pci_core_device *vdev)
+{
+	struct vfio_pci_cxl_state *cxl = vdev->cxl;
+
+	if (!cxl->region)
+		return;
+
+	cxl_unregister_region(cxl->region);
+	cxl->region = NULL;
+
+	if (cxl->precommitted)
+		return;
+
+	cxl_dpa_free(cxl->cxled);
+	cxl_put_root_decoder(cxl->cxlrd);
+}
+
+static int vfio_cxl_create_region_helper(struct vfio_pci_core_device *vdev,
+					 resource_size_t capacity)
+{
+	struct vfio_pci_cxl_state *cxl = vdev->cxl;
+	struct pci_dev *pdev = vdev->pdev;
+	int ret;
+
+	if (cxl->precommitted) {
+		cxl->cxled = cxl_get_committed_decoder(cxl->cxlmd,
+						       &cxl->region);
+		if (IS_ERR(cxl->cxled))
+			return PTR_ERR(cxl->cxled);
+	} else {
+		ret = vfio_cxl_create_cxl_region(vdev, capacity);
+		if (ret)
+			return ret;
+	}
+
+	if (cxl->region) {
+		struct range range;
+
+		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, "Precommitted decoder: HPA 0x%llx size %lu MB\n",
+			cxl->region_hpa, cxl->region_size >> 20);
+	} else {
+		pci_err(pdev, "Failed to create CXL region\n");
+		ret = -ENODEV;
+		goto failed;
+	}
+
+	return 0;
+
+failed:
+	vfio_cxl_destroy_cxl_region(vdev);
+	return ret;
+}
+
 /**
  * vfio_pci_cxl_detect_and_init - Detect and initialize CXL Type-2 device
  * @vdev: VFIO PCI device
@@ -172,6 +278,12 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 
 	pci_disable_device(pdev);
 
+	ret = vfio_cxl_create_region_helper(vdev, SZ_256M);
+	if (ret)
+		goto failed;
+
+	cxl->precommitted = true;
+
 	return;
 
 failed:
@@ -181,6 +293,10 @@ void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev)
 
 void vfio_pci_cxl_cleanup(struct vfio_pci_core_device *vdev)
 {
-	if (!vdev->cxl)
+	struct vfio_pci_cxl_state *cxl = vdev->cxl;
+
+	if (!cxl || !cxl->region)
 		return;
+
+	vfio_cxl_destroy_cxl_region(vdev);
 }
diff --git a/drivers/vfio/pci/cxl/vfio_cxl_priv.h b/drivers/vfio/pci/cxl/vfio_cxl_priv.h
index 57fed39a80da..985680842a13 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 __iomem		    *region_vaddr;
 	resource_size_t              hdm_reg_offset;
 	size_t                       hdm_reg_size;
 	resource_size_t              comp_reg_offset;
@@ -24,6 +28,7 @@ struct vfio_pci_cxl_state {
 	u32                          hdm_count;
 	u16                          dvsec;
 	u8                           comp_reg_bar;
+	bool                         precommitted;
 };
 
 /*
diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h
index d7df5538dcde..818d99f098bf 100644
--- a/drivers/vfio/pci/vfio_pci_priv.h
+++ b/drivers/vfio/pci/vfio_pci_priv.h
@@ -137,6 +137,9 @@ static inline void vfio_pci_dma_buf_move(struct vfio_pci_core_device *vdev,
 
 void vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev);
 void vfio_pci_cxl_cleanup(struct vfio_pci_core_device *vdev);
+int vfio_cxl_create_cxl_region(struct vfio_pci_core_device *vdev,
+			       resource_size_t size);
+void vfio_cxl_destroy_cxl_region(struct vfio_pci_core_device *vdev);
 
 #else
 
@@ -144,6 +147,11 @@ static inline void
 vfio_pci_cxl_detect_and_init(struct vfio_pci_core_device *vdev) { }
 static inline void
 vfio_pci_cxl_cleanup(struct vfio_pci_core_device *vdev) { }
+static inline int vfio_cxl_create_cxl_region(struct vfio_pci_core_device *vdev,
+					     resource_size_t size)
+{ return 0; }
+static inline void
+vfio_cxl_destroy_cxl_region(struct vfio_pci_core_device *vdev) { }
 
 #endif /* CONFIG_VFIO_CXL_CORE */
 
-- 
2.25.1