[PATCH v8 2/4] cxl/region: Don't leak tolerated RAM -EFAULT from unmapped poison scan

[Richard Cheng]

CXL 3.0 section 8.2.9.8.4.1 requires Get Poison List to return Invalid
Physical Address for a volatile range when the device does not support
volatile poison lists.

For example, consider a memdev with a single RAM partition and a
committed decoder covering only part of it:

  RAM partition: [ committed decoder ][ unmapped tail ]

On a device without volatile poison-list support, querying this tail
returns Invalid Physical Address, which cxl_internal_send_cmd() maps
to -EFAULT. The driver tolerates this response for RAM because volatile
poison-list support is optional.

When cxl_get_poison_unmapped() was converted to iterate over partitions,
the RAM-specific error handling became a continue without clearing rc.
If no subsequent query overwrites rc, the function returns the tolerated
-EFAULT and incorrectly reports the enumeration as failed.

Clear rc before continuing, restoring the previous handling of this
expected response for RAM partitions.

Fixes: be5cbd0840275 ("cxl: Kill enum cxl_decoder_mode")
Reviewed-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Reviewed-by: Alison Schofield <alison.schofield@xxxxxxxxx>
Signed-off-by: Richard Cheng <icheng@xxxxxxxxxx>
---
 drivers/cxl/core/region.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
index 7c7287315d72..042356c71ed7 100644
--- a/drivers/cxl/core/region.c
+++ b/drivers/cxl/core/region.c
@@ -2954,8 +2954,10 @@ static int cxl_get_poison_unmapped(struct cxl_memdev *cxlmd,
 		if (!length)
 			continue;
 		rc = cxl_mem_get_poison(cxlmd, offset, length, NULL);
-		if (poison_efault_forgiven(rc, cxlds->part[i].mode))
+		if (poison_efault_forgiven(rc, cxlds->part[i].mode)) {
+			rc = 0;
 			continue;
+		}
 		if (rc)
 			break;
 	}
-- 
2.43.0