[PATCH] drm/i915/gvt: fix crash at function release_shadow_wa_ctx

[Du, Changbin]

hi, Zhenyu,
Please check this one as high priority. This issue got reproduced eaily
after host chip reset. And please kindly pici it into gvt-stable branch.
Thanks.

On Thu, Feb 09, 2017 at 04:50:15PM +0800, changbin.du at intel.com wrote:
> From: Changbin Du <changbin.du at intel.com>
> 
> In function dispatch_workload(), if it fail before calling
> intel_gvt_scan_and_shadow_wa_ctx(), the indirect ctx will
> not be shadowed so no cleaup need. wa_ctx->indirect_ctx.obj
> indicate whether indirect_ctx is shadowed. The obj is null
> if it is unshadowed.
> 
> BUG: unable to handle kernel NULL pointer dereference at
> 00000000000001a0
> IP: complete_execlist_workload+0x2c9/0x3e0 [i915]
> Oops: 0002 [#1] SMP
> task: ffff939546d2d880 task.stack: ffffbd9b82ac4000
> RIP: 0010:complete_execlist_workload+0x2c9/0x3e0 [i915]
> RSP: 0018:ffffbd9b82ac7dd8 EFLAGS: 00010202
> RAX: 0000000000000000 RBX: ffff9393c725b540 RCX: 0000000000000006
> RDX: 0000000000000007 RSI: 0000000000000202 RDI: ffff939559c8dd00
> RBP: ffffbd9b82ac7e18 R08: 0000000000000001 R09: 000000000120dd8f
> R10: 0000000000000000 R11: 000000000120dd8f R12: ffff9393c725b540
> R13: ffff9393c725b618 R14: ffffbd9b81f0d000 R15: ffff939520e0e000
> FS:  0000000000000000(0000) GS:ffff939559c80000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000001a0 CR3: 000000043d664000 CR4: 00000000003426e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  workload_thread+0x312/0xd70 [i915]
>  ? __wake_up_sync+0x20/0x20
>  ? wake_atomic_t_function+0x60/0x60
>  kthread+0x101/0x140
> 
> Signed-off-by: Changbin Du <changbin.du at intel.com>
> ---
>  drivers/gpu/drm/i915/gvt/execlist.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/gvt/execlist.c b/drivers/gpu/drm/i915/gvt/execlist.c
> index 3408373..46eb9fd 100644
> --- a/drivers/gpu/drm/i915/gvt/execlist.c
> +++ b/drivers/gpu/drm/i915/gvt/execlist.c
> @@ -487,7 +487,7 @@ static void release_shadow_batch_buffer(struct intel_vgpu_workload *workload)
>  
>  static void release_shadow_wa_ctx(struct intel_shadow_wa_ctx *wa_ctx)
>  {
> -	if (wa_ctx->indirect_ctx.size == 0)
> +	if (!wa_ctx->indirect_ctx.obj)
>  		return;
>  
>  	i915_gem_object_unpin_map(wa_ctx->indirect_ctx.obj);
> -- 
> 2.7.4
> 

-- 
Thanks,
Changbin Du
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