From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A47DA4252D0 for ; Mon, 13 Jul 2026 13:19:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783948779; cv=none; b=SixwZSHXwQ9yoCIv3psVJXvcifyAlurJOeW0KWxlJNiXx8M9aBSZgQ66zKo2uRpst91PORNG5aQo+KkdFVa8Z6Kc//5f0KiEQIyuomsDgzwDrBPtJ8+3xE30RGpYmuzmwVU8ZK1jIlpbuVeSa/M/H06jzPCMIqB+W40Kk/Oh0JY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783948779; c=relaxed/simple; bh=l8X0672jEDBhvFII8sAijx/NPR5pqAKdKY+f7IcKmAQ=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=PyWtiB4psN47w39pG/HMNcfsmbnfUqI2VoCnPxGzUn5AykHrjQ76IlZrc7Q0FO4VHVnIrRy9Q9an2xiyXz27gdlCdhsvjUi37b4DTwJMZR4RhjJlr4XZA8SPyC9XnOMNSZms7f7s2cDp5kqh1xF1mwFeZuqtFX2+rspgQudc7E8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=ENJWee1s; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="ENJWee1s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 15EC61F000E9; Mon, 13 Jul 2026 13:19:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1783948778; bh=LPG7+AgcLDo0tbT7Kfy6/tqBGIagqbUbcXQxbn7+ZOY=; h=Subject:To:Cc:From:Date; b=ENJWee1sQZveBSqHUTPYGy7Z+xhwYfUTA3nhjubgiG7tLbdvBd00XHnmBlhIWBSYv 8bQkwWzXnpsumNES5DP79neKVBFgOBQq2N6BYX/q4ln5/JReKngP5HT+X1ccsEWxIK b47hyvZf2/4dd/L8duDuvu4HYiyEgKWGwK5nynQM= Subject: FAILED: patch "[PATCH] vfio/mlx5: Fix racy bitfields and tighten struct layout" failed to apply to 6.6-stable tree To: alex.williamson@nvidia.com,alex@shazbot.org,kevin.tian@intel.com,yishaih@nvidia.com Cc: From: Date: Mon, 13 Jul 2026 15:07:51 +0200 Message-ID: <2026071351-hypnotist-breeching-8539@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x f2365a63b02ddea32e7db78b742c2503ec7b81f1 # git commit -s git send-email --to '' --in-reply-to '2026071351-hypnotist-breeching-8539@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From f2365a63b02ddea32e7db78b742c2503ec7b81f1 Mon Sep 17 00:00:00 2001 From: Alex Williamson Date: Mon, 15 Jun 2026 13:12:32 -0600 Subject: [PATCH] vfio/mlx5: Fix racy bitfields and tighten struct layout Bitfield operations are not atomic, they use a read-modify-write pattern, therefore we should be careful not to pack bitfields that can be concurrently updated into the same storage unit. This split takes a binary approach: flags that are only modified pre/post open/close remain bitfields, flags modified from user action, including actions that reach across to another device (ex. reset) use dedicated storage units. Note mlx5_vhca_page_tracker.status is relocated to fill the alignment hole this split exposes. Bitfield justifications: migrate_cap: written only in mlx5vf_cmd_set_migratable() at probe chunk_mode: written only in mlx5vf_cmd_set_migratable() at probe mig_state_cap: written only in mlx5vf_cmd_set_migratable() at probe Dedicated storage units: mdev_detach: written in the VF attach/detach event notifier mlx5fv_vf_event() at runtime log_active: written in mlx5vf_start_page_tracker()/ mlx5vf_stop_page_tracker() during runtime dirty tracking deferred_reset: written in mlx5vf_state_mutex_unlock()/ mlx5vf_pci_aer_reset_done() during runtime reset handling is_err: set by tracker error handling and dirty-log polling at runtime object_changed: set by tracker event handling and cleared by dirty-log polling at runtime Fixes: 61a2f1460fd0 ("vfio/mlx5: Manage the VF attach/detach callback from the PF") Fixes: 79c3cf279926 ("vfio/mlx5: Init QP based resources for dirty tracking") Fixes: f886473071d6 ("vfio/mlx5: Add support for tracker object change event") Cc: Yishai Hadas Cc: stable@vger.kernel.org Assisted-by: Claude:claude-opus-4-8 Signed-off-by: Alex Williamson Reviewed-by: Kevin Tian Link: https://lore.kernel.org/r/20260615191241.688297-5-alex.williamson@nvidia.com Signed-off-by: Alex Williamson diff --git a/drivers/vfio/pci/mlx5/cmd.h b/drivers/vfio/pci/mlx5/cmd.h index deed0f132f39..c86d8b243a52 100644 --- a/drivers/vfio/pci/mlx5/cmd.h +++ b/drivers/vfio/pci/mlx5/cmd.h @@ -158,26 +158,29 @@ struct mlx5_vhca_qp { struct mlx5_vhca_page_tracker { u32 id; u32 pdn; - u8 is_err:1; - u8 object_changed:1; + /* Flags modified at runtime - dedicated storage unit */ + u8 is_err; + u8 object_changed; + int status; struct mlx5_uars_page *uar; struct mlx5_vhca_cq cq; struct mlx5_vhca_qp *host_qp; struct mlx5_vhca_qp *fw_qp; struct mlx5_nb nb; - int status; }; struct mlx5vf_pci_core_device { struct vfio_pci_core_device core_device; int vf_id; u16 vhca_id; + /* Flags only modified on setup/release - bitfield ok */ u8 migrate_cap:1; - u8 deferred_reset:1; - u8 mdev_detach:1; - u8 log_active:1; u8 chunk_mode:1; u8 mig_state_cap:1; + /* Flags modified at runtime - dedicated storage unit */ + u8 mdev_detach; + u8 log_active; + u8 deferred_reset; struct completion tracker_comp; /* protect migration state */ struct mutex state_mutex;