[PATCH] cxl/core: Check existence of cxl_memdev_state in poison test

[Alison Schofield <alison.schofield@intel.com>]

Before now, all CXL memdevs were assumed to have a mailbox-backed
cxl_memdev_state, so poison command checks could safely dereference
the @mds.

With the introduction of Type 2 devices, a memdev may not implement
a mailbox interface, and so there is no associated cxl_memdev_state.
Guard against this case by returning false when @mds is absent.

Signed-off-by: Alison Schofield <alison.schofield@intel.com>
---
 drivers/cxl/core/memdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/cxl/core/memdev.c b/drivers/cxl/core/memdev.c
index 273c22118d3d..591425866045 100644
--- a/drivers/cxl/core/memdev.c
+++ b/drivers/cxl/core/memdev.c
@@ -204,6 +204,9 @@ bool cxl_memdev_has_poison_cmd(struct cxl_memdev *cxlmd,
 {
 	struct cxl_memdev_state *mds = to_cxl_memdev_state(cxlmd->cxlds);
 
+	if (!mds)
+		return 0;
+
 	return test_bit(cmd, mds->poison.enabled_cmds);
 }
 
-- 
2.37.3