[Intel-gfx] [PATCH] drm/i915/guc: Verify result from CTB (de)register action

[Michal Wajdeczko]

In commit b839a869dfc9 ("drm/i915/guc: Add support for data
reporting in GuC responses") we missed the hypothetical case
that GuC might return positive non-zero value as success data.

While that would be lucky treated as error case, and at the
end will result in reporting valid -EIO, in the meantime this
value will be passed to ERR_PTR that could be misleading.

Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Dan Carpenter <dan.carpenter at oracle.com>
---
 drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
index 8f7b148fef58..72ce234f764d 100644
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c
@@ -149,9 +149,12 @@ static int guc_action_register_ct_buffer(struct intel_guc *guc,
 		sizeof(struct guc_ct_buffer_desc),
 		type
 	};
+	int ret;
 
 	/* Can't use generic send(), CT registration must go over MMIO */
-	return intel_guc_send_mmio(guc, action, ARRAY_SIZE(action), NULL, 0);
+	ret = intel_guc_send_mmio(guc, action, ARRAY_SIZE(action), NULL, 0);
+
+	return ret > 0 ? -EPROTO : ret;
 }
 
 static int ct_register_buffer(struct intel_guc_ct *ct, u32 desc_addr, u32 type)
@@ -171,9 +174,12 @@ static int guc_action_deregister_ct_buffer(struct intel_guc *guc, u32 type)
 		CTB_OWNER_HOST,
 		type
 	};
+	int ret;
 
 	/* Can't use generic send(), CT deregistration must go over MMIO */
-	return intel_guc_send_mmio(guc, action, ARRAY_SIZE(action), NULL, 0);
+	ret = intel_guc_send_mmio(guc, action, ARRAY_SIZE(action), NULL, 0);
+
+	return ret > 0 ? -EPROTO : ret;
 }
 
 static int ct_deregister_buffer(struct intel_guc_ct *ct, u32 type)
-- 
2.25.1