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 DF0DC3BED2D; Thu, 16 Jul 2026 13:40:50 +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=1784209252; cv=none; b=WxeQMFNnHUwcjJWevzlPJVPCFMSIXho2HgGSSmbWzsyi//C1b0k1rtpHb68XmMfJY+GOK5ky1GjIsvUdpnYl2ZMgSvdzPuH8d5lYiQQcSraPteOgN1v35zePV/q/1Uyx5WErVkPgZ1UJldmqrKg42MwR3leb4YZSsUFFyV1DCpY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784209252; c=relaxed/simple; bh=0raAx3s8/oVfXAXyMAsz2H4T7IrH/t5B6LjxGYJz/sw=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=a6c5kQ2EygL7NeMw5EQSzsJ00XWmGaiPA/oEppVWgWRkOwISUSvublsTHSiJxCUEYjnlusJDFSWl5NK+d/1LYzIOeQCNzlR60QOS9EzXAZyATVebDZOmlyp40xAuYmeSLhis/+2DRMAFh4A5yfwMbOh0F5127yI3DNXWoMIazQM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=KqjaEFMi; 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="KqjaEFMi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E38CF1F000E9; Thu, 16 Jul 2026 13:40:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784209250; bh=YGs0+L6lFk8E/eoUSC15YWVJDpRMRNxVr12O8PILOFY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=KqjaEFMierUtxPsGpOgKr68sI8+p0STduJS6kB80WyepSTeN/wMixyN/eo7xabFrf tIyGWKjDyeVbqVqY0G/NNX+gLV5CWiFKa3VayPXcAi3vQnQVzgaUU3Uw/OHcfKKCbV Wxzdu5x3yg+xhkOBmD5xHxojwGD2EQYlVE/wo2kw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yishai Hadas , Alex Williamson , Kevin Tian , Alex Williamson Subject: [PATCH 7.1 112/518] vfio/mlx5: Fix racy bitfields and tighten struct layout Date: Thu, 16 Jul 2026 15:26:20 +0200 Message-ID: <20260716133050.302256478@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133047.772246337@linuxfoundation.org> References: <20260716133047.772246337@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Williamson commit f2365a63b02ddea32e7db78b742c2503ec7b81f1 upstream. 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 Signed-off-by: Greg Kroah-Hartman --- drivers/vfio/pci/mlx5/cmd.h | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) --- 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;