Re: [PATCH 1/2] drm/xe/guc: Prevent use of uninitialized mutex

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Mon, Jul 01, 2024 at 04:15:28PM -0700, Vinay Belgaumkar wrote:
> When skip_guc_pc is set and/or this is for a VF.
>
> Fixes: 3b1592fb7835 ("drm/xe/lnl: Apply Wa_22019338487")
> Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_guc_pc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
> index d88f5e960fbd..f7b468930697 100644
> --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> @@ -26,6 +26,7 @@
>  #include "xe_mmio.h"
>  #include "xe_pcode.h"
>  #include "xe_pm.h"
> +#include "xe_sriov.h"
>  #include "xe_wa.h"
>  
>  #define MCHBAR_MIRROR_BASE_SNB	0x140000
> @@ -825,6 +826,9 @@ int xe_guc_pc_restore_stashed_freq(struct xe_guc_pc *pc)
>  {
>  	int ret = 0;
>  
> +	if (IS_SRIOV_VF(pc_to_xe(pc)) 

Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>

are all the other accesses protected?
likely because the freq sysfs is not available in VF mode?

|| pc_to_xe(pc)->info.skip_guc_pc)
> +		return 0;
> +

I don't like this skip_guc_pc... we might revisit later
to find a cleaner way...

anyway, let's move with this patch. the rest is follow up.

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

>  	mutex_lock(&pc->freq_lock);
>  	ret = pc_set_max_freq(pc, pc->stashed_max_freq);
>  	if (!ret)
> -- 
> 2.38.1
>