linux-kernel - Re: [PATCH v3 03/28] drm/xe/pf: Convert control state to bitmap

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <612b77d4-236b-411b-9b6f-93c6924e8a1d@intel.com>
Date: Thu, 30 Oct 2025 23:57:28 +0100
From: Michal Wajdeczko <michal.wajdeczko@...el.com>
To: Michał Winiarski <michal.winiarski@...el.com>, "Alex
 Williamson" <alex@...zbot.org>, Lucas De Marchi <lucas.demarchi@...el.com>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	"Rodrigo Vivi" <rodrigo.vivi@...el.com>, Jason Gunthorpe <jgg@...pe.ca>,
	Yishai Hadas <yishaih@...dia.com>, Kevin Tian <kevin.tian@...el.com>, Shameer
 Kolothum <skolothumtho@...dia.com>, <intel-xe@...ts.freedesktop.org>,
	<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>, Matthew Brost
	<matthew.brost@...el.com>
CC: <dri-devel@...ts.freedesktop.org>, Jani Nikula
	<jani.nikula@...ux.intel.com>, Joonas Lahtinen
	<joonas.lahtinen@...ux.intel.com>, Tvrtko Ursulin <tursulin@...ulin.net>,
	David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, "Lukasz
 Laguna" <lukasz.laguna@...el.com>, Christoph Hellwig <hch@...radead.org>,
	kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v3 03/28] drm/xe/pf: Convert control state to bitmap



On 10/30/2025 9:31 PM, Michał Winiarski wrote:
> In upcoming changes, the number of states will increase as a result of
> introducing SAVE and RESTORE states.
> This means that using unsigned long as underlying storage won't work on
> 32-bit architectures, as we'll run out of bits.
> Use bitmap instead.
> 
> Reported-by: kernel test robot <lkp@...el.com>
> Closes: https://lore.kernel.org/oe-kbuild-all/202510231918.XlOqymLC-lkp@intel.com/
> Signed-off-by: Michał Winiarski <michal.winiarski@...el.com>
> ---
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c       | 2 +-
>  drivers/gpu/drm/xe/xe_gt_sriov_pf_control_types.h | 5 +++--
>  2 files changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> index 9de05db1f0905..8a2577fda4198 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c
> @@ -225,7 +225,7 @@ static unsigned long *pf_peek_vf_state(struct xe_gt *gt, unsigned int vfid)
>  {
>  	struct xe_gt_sriov_control_state *cs = pf_pick_vf_control(gt, vfid);
>  
> -	return &cs->state;
> +	return cs->state;
>  }
>  
>  static bool pf_check_vf_state(struct xe_gt *gt, unsigned int vfid,
> diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control_types.h b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control_types.h
> index c80b7e77f1ad2..3ba6ad886c939 100644
> --- a/drivers/gpu/drm/xe/xe_gt_sriov_pf_control_types.h
> +++ b/drivers/gpu/drm/xe/xe_gt_sriov_pf_control_types.h
> @@ -73,7 +73,8 @@ enum xe_gt_sriov_control_bits {
>  	XE_GT_SRIOV_STATE_STOP_FAILED,
>  	XE_GT_SRIOV_STATE_STOPPED,
>  
> -	XE_GT_SRIOV_STATE_MISMATCH = BITS_PER_LONG - 1,
> +	XE_GT_SRIOV_STATE_MISMATCH,
> +	XE_GT_SRIOV_STATE_MAX,

while this feels handy, this MAX enumerator is not a real state
and as such shouldn't be passed to any function that expects
"enum"

since we know (and want) to keep MISMATCH state as last one
(aka top bit) then maybe tag it and use separate define:

-	XE_GT_SRIOV_STATE_MISMATCH = BITS_PER_LONG - 1,
+	XE_GT_SRIOV_STATE_MISMATCH /* always keep as last */
+
+ #define XE_GT_SRIOV_NUM_STATES (XE_GT_SRIOV_STATE_MISMATCH + 1)

>  };
>  
>  /**
> @@ -83,7 +84,7 @@ enum xe_gt_sriov_control_bits {
>   */
>  struct xe_gt_sriov_control_state {
>  	/** @state: VF state bits */
> -	unsigned long state;
> +	DECLARE_BITMAP(state, XE_GT_SRIOV_STATE_MAX);
>  
>  	/** @done: completion of async operations */
>  	struct completion done;