diff mbox series

[v5,24/27] cxl: add region flag for precluding a device memory to be used for dax

Message ID 20241118164434.7551-25-alejandro.lucero-palau@amd.com (mailing list archive)
State New
Headers show
Series cxl: add type2 device basic support | expand

Commit Message

Lucero Palau, Alejandro Nov. 18, 2024, 4:44 p.m. UTC 
From: Alejandro Lucero <alucerop@amd.com>

By definition a type2 cxl device will use the host managed memory for
specific functionality, therefore it should not be available to other
uses. However, a dax interface could be just good enough in some cases.

Add a flag to a cxl region for specifically state to not create a dax
device. Allow a Type2 driver to set that flag at region creation time.

Signed-off-by: Alejandro Lucero <alucerop@amd.com>
---
 drivers/cxl/core/region.c | 10 +++++++++-
 drivers/cxl/cxl.h         |  3 +++
 drivers/cxl/cxlmem.h      |  3 ++-
 include/cxl/cxl.h         |  3 ++-
 4 files changed, 16 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 70549d42c2e3..eff3ad788077 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -3558,7 +3558,8 @@  __construct_new_region(struct cxl_root_decoder *cxlrd,
  * cxl_region driver.
  */
 struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
-				     struct cxl_endpoint_decoder *cxled)
+				     struct cxl_endpoint_decoder *cxled,
+				     bool avoid_dax)
 {
 	struct cxl_region *cxlr;
 
@@ -3574,6 +3575,10 @@  struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
 		drop_region(cxlr);
 		return ERR_PTR(-ENODEV);
 	}
+
+	if (avoid_dax)
+		set_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags);
+
 	return cxlr;
 }
 EXPORT_SYMBOL_NS_GPL(cxl_create_region, CXL);
@@ -3713,6 +3718,9 @@  static int cxl_region_probe(struct device *dev)
 	case CXL_DECODER_PMEM:
 		return devm_cxl_add_pmem_region(cxlr);
 	case CXL_DECODER_RAM:
+		if (test_bit(CXL_REGION_F_AVOID_DAX, &cxlr->flags))
+			return 0;
+
 		/*
 		 * The region can not be manged by CXL if any portion of
 		 * it is already online as 'System RAM'
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 1e0e797b9303..ee3385db5663 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -512,6 +512,9 @@  struct cxl_region_params {
  */
 #define CXL_REGION_F_NEEDS_RESET 1
 
+/* Allow Type2 drivers to specify if a dax region should not be created. */
+#define CXL_REGION_F_AVOID_DAX 2
+
 /**
  * struct cxl_region - CXL region
  * @dev: This region's device
diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
index 9d874f1cb3bf..cc2e2a295f3d 100644
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -875,5 +875,6 @@  struct seq_file;
 struct dentry *cxl_debugfs_create_dir(const char *dir);
 void cxl_dpa_debug(struct seq_file *file, struct cxl_dev_state *cxlds);
 struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
-				     struct cxl_endpoint_decoder *cxled);
+				     struct cxl_endpoint_decoder *cxled,
+				     bool avoid_dax);
 #endif /* __CXL_MEM_H__ */
diff --git a/include/cxl/cxl.h b/include/cxl/cxl.h
index d295af4f5f9e..2a8ebabfc1dd 100644
--- a/include/cxl/cxl.h
+++ b/include/cxl/cxl.h
@@ -73,7 +73,8 @@  struct cxl_endpoint_decoder *cxl_request_dpa(struct cxl_memdev *cxlmd,
 					     resource_size_t max);
 int cxl_dpa_free(struct cxl_endpoint_decoder *cxled);
 struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
-				     struct cxl_endpoint_decoder *cxled);
+				     struct cxl_endpoint_decoder *cxled,
+				     bool avoid_dax);
 
 int cxl_accel_region_detach(struct cxl_endpoint_decoder *cxled);
 #endif