drm/i915/guc: Don't try to create log runtime if there is no log

In case of GuC initialization failure we may continue with driver
load, but we wrongly assume that GuC is fully functional. This
leads to the BUG as we attempt to access non-existing log vma.

[26386.121085] BUG: unable to handle kernel NULL pointer dereference at 00000000000000a0
[26386.121225] IP: guc_log_runtime_create+0x23/0xe0 [i915]
[26386.121763] Call Trace:
[26386.121870]  guc_log_late_setup+0xfd/0x140 [i915]
[26386.121969]  i915_driver_load+0x7ab/0x1730 [i915]
[26386.122069]  i915_pci_probe+0x2d/0x90 [i915]
[26386.122089]  pci_device_probe+0x9c/0x120
[26386.122107]  driver_probe_device+0x2a9/0x490
[26386.122126]  __driver_attach+0xd9/0xe0
[26386.122143]  ? driver_probe_device+0x490/0x490
[26386.122158]  bus_for_each_dev+0x57/0x90
[26386.122175]  bus_add_driver+0x1eb/0x260
[26386.122190]  ? 0xffffffffa069a000
[26386.122206]  driver_register+0x52/0xc0
[26386.122220]  ? 0xffffffffa069a000
[26386.122234]  do_one_initcall+0x39/0x170
[26386.122252]  ? kmem_cache_alloc_trace+0x1fd/0x2e0
[26386.122273]  do_init_module+0x56/0x1ec
[26386.122289]  load_module+0x219e/0x2550
[26386.122309]  ? vfs_read+0x121/0x140
[26386.122331]  ? SyS_finit_module+0xa5/0xe0
[26386.122346]  SyS_finit_module+0xa5/0xe0
[26386.122371]  entry_SYSCALL_64_fastpath+0x22/0x8f

Signed-off-by: Michal Wajdeczko <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Michal Winiarski <[email protected]>
Cc: Daniele Ceraolo Spurio <[email protected]>
Cc: Sagar Arun Kamble <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]
Reviewed-by: Sagar Arun Kamble <[email protected]>
Signed-off-by: Chris Wilson <[email protected]>

diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
index 3fbe93ac81dcd9f0392f4e7e6926b4c97b15ff6c..7b5074e2120c25a5a8d6341951ba8f01a12c65dd 100644 (file)
--- a/drivers/gpu/drm/i915/intel_guc_log.c
+++ b/drivers/gpu/drm/i915/intel_guc_log.c
@@ -397,6 +397,9 @@ static int guc_log_runtime_create(struct intel_guc *guc)
 
        lockdep_assert_held(&dev_priv->drm.struct_mutex);
 
+       if (!guc->log.vma)
+               return -ENODEV;
+
        GEM_BUG_ON(guc_log_has_runtime(guc));
 
        ret = i915_gem_object_set_to_wc_domain(guc->log.vma->obj, true);