drm/i915/guc: Don't go bang in GuC log if no GuC

If the GuC has failed to load for any reason and then the user pokes
the debugfs GuC log interface, a BUG and/or null pointer deref can
occur. Don't let that happen.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211210044022.1842938-5-John.C.Harrison@Intel.com

diff --git a/drivers/gpu/drm/i915/gt/uc/intel_guc_log_debugfs.c b/drivers/gpu/drm/i915/gt/uc/intel_guc_log_debugfs.c
index 46026c2..8fd0680 100644 (file)
--- a/drivers/gpu/drm/i915/gt/uc/intel_guc_log_debugfs.c
+++ b/drivers/gpu/drm/i915/gt/uc/intel_guc_log_debugfs.c
@@ -31,7 +31,7 @@ static int guc_log_level_get(void *data, u64 *val)
 {
        struct intel_guc_log *log = data;
 
-       if (!intel_guc_is_used(log_to_guc(log)))
+       if (!log->vma)
                return -ENODEV;
 
        *val = intel_guc_log_get_level(log);
@@ -43,7 +43,7 @@ static int guc_log_level_set(void *data, u64 val)
 {
        struct intel_guc_log *log = data;
 
-       if (!intel_guc_is_used(log_to_guc(log)))
+       if (!log->vma)
                return -ENODEV;
 
        return intel_guc_log_set_level(log, val);