[PATCH v2] cxl/region: Add dev_dbg() detail on failure to allocate HPA space

[alison.schofield@intel.com]

From: Alison Schofield <alison.schofield@intel.com>

When the region driver fails while allocating HPA space for a
new region it can be because the parent resource, the CXL Window,
has no more available space.

In that case, the debug user sees this message:
cxl_core:alloc_hpa:555: cxl region2: failed to allocate HPA: -34

Expand the message like this:
cxl_core:alloc_hpa:555: cxl region8: HPA allocation error:-34 for size:0x20000000 in CXL Window 0 [mem 0xf010000000-0xf04fffffff flags 0x200]

Now the debug user can examine /proc/iomem and consider actions
like removing other allocations in that space or reducing the
size of their region request.

Suggested-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Alison Schofield <alison.schofield@intel.com>
Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
---

Changes in v2:
- Improve the message text (Vishal)
- Add reviewed by tags (DaveJ, Vishal)
- Link to v1:
https://lore.kernel.org/linux-cxl/20231114040147.1124696-1-alison.schofield@intel.com/


 drivers/cxl/core/region.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 56e575c79bb4..ec792af873c4 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -552,8 +552,9 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size)
 	res = alloc_free_mem_region(cxlrd->res, size, SZ_256M,
 				    dev_name(&cxlr->dev));
 	if (IS_ERR(res)) {
-		dev_dbg(&cxlr->dev, "failed to allocate HPA: %ld\n",
-			PTR_ERR(res));
+		dev_dbg(&cxlr->dev,
+			"HPA allocation error:%ld for size:%#llx in %s %pr\n",
+			PTR_ERR(res), size, cxlrd->res->name, cxlrd->res);
 		return PTR_ERR(res);
 	}
 

base-commit: b85ea95d086471afb4ad062012a4d73cd328fa86
-- 
2.37.3