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 498FB35C6B3; Tue, 21 Jul 2026 21:48:22 +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=1784670504; cv=none; b=qtNcSAZ/zPXOHgvzQisY8/K7S3EQkuLmbMNv/MWMtrs28mZUoihnByUDGrLK76UHgq6dpXwozNaBCYHOW/QfxTmB2TPIz+Vk78Tsfza9aXYRb5eJKBqmFFyHlgBW4nnMc6hqrFV3S1Dm1oOXSH4FWZw+zBx44t6k906PvpNjwPE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670504; c=relaxed/simple; bh=4sTZLytacp3PiErLN+S9COg9Q2/8KLnjicTec5j31II=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QKBC/fa21A2S2Mu/Q3iATZjxy19FCROC0L85P0PXRBnfuYy/c6PI09meP/JLR5WYAMNn3f6kb5w+Ds4/Qg7qgCavQGIwKI7Jll+mOONX5cWzPtPg9GjhaG3Xf5TCKLwAawHhUKHtBfu7YTBt7+vWV8VTTZPCBpT5orFQ9MUbgLc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=pJ8wXFn5; 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="pJ8wXFn5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5E5041F00A3A; Tue, 21 Jul 2026 21:48:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784670502; bh=5jbJPgPJeTX3PRb8CFm/Qs1hLfyi7AHAy6QGudGh1jU=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=pJ8wXFn5U83oGt9CJ1GaAEtFw0xUS7fgMr8chew9GTOZfQokzXNWT0MFNPY4u/qtT nvtgpunK+8oiJkDezaqAWNTjZEAMSTmKG9pGk2HJ9pLgfVm3mIKErQYP6o1NylgVdO TcEvIcsTuVMwD4Oqn6YCdcQJW9SNDb7tkMjQGr9I= 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 , Sasha Levin Subject: [PATCH 6.1 0957/1067] vfio/mlx5: Fix racy bitfields and tighten struct layout Date: Tue, 21 Jul 2026 17:25:58 +0200 Message-ID: <20260721152445.950592607@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Williamson [ Upstream commit f2365a63b02ddea32e7db78b742c2503ec7b81f1 ] 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: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/vfio/pci/mlx5/cmd.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/drivers/vfio/pci/mlx5/cmd.h +++ b/drivers/vfio/pci/mlx5/cmd.h @@ -82,23 +82,26 @@ struct mlx5_vhca_qp { struct mlx5_vhca_page_tracker { u32 id; u32 pdn; - u8 is_err:1; + /* Flags modified at runtime - dedicated storage unit */ + u8 is_err; + 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; + /* 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;