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 569D941A76E; Thu, 16 Jul 2026 14:03:49 +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=1784210630; cv=none; b=jh6GgbH5kicZNKK/QIubZvSW56gaUQ4ukK7Xm/PWcxgX4JNKLAJPVOu7iikNESqde/+F11nyfEmu5Yh+b/qU4MAWP/HTLaGKz+dw20oUI6XmOK5/mpRGk+4k8bQbmBp4kRz59Z4ur0aOEZEhqqsgZAKW1y6K+zZO7nC54Fd0J0E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784210630; c=relaxed/simple; bh=TPSMoZMVSNCgGE1kgLAyfP8awWzHHZaOur3CDvVjyd8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hhgNW/FaSZCT1H3TSVnNqxQkj0Y7Bk/y61WmUBZbEv5UvNaKEKqmqmSjJuXYL1qkhLEwIpww9cluQ8pE9CTJnCNiMEWvh9CF5z5JxBLmHdeuDup5hw2RTQ9/PQ19sZfXVza9HzVd3Pc90mzTAQPLpInmCujfFGIwkJOwP6EffuA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oa8o4cP9; 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="oa8o4cP9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB3B31F000E9; Thu, 16 Jul 2026 14:03:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784210629; bh=cCylkgke/uz3s0oT1lUwglTdcZBoWgHkVwDvdDcYDFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=oa8o4cP9kGzWz4voppDkQTWqsl5Umz68udFbT1DocAoVgk5oT9Xk70AJA5e21wusF xLLEGXoGf7jZsfoZa89PldE/vzaO6PyV7zYbUk0McxKIZVudmM4GJT3fUhClqtuGeo 5NYz2SmXHqk7pp1F8IoPf5Rkwpmk6iGikLsiG63I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alex Williamson , Kevin Tian , Alex Williamson Subject: [PATCH 6.18 119/480] vfio/pci: Fix racy bitfields and tighten struct layout Date: Thu, 16 Jul 2026 15:27:46 +0200 Message-ID: <20260716133047.280092349@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260716133044.672218725@linuxfoundation.org> References: <20260716133044.672218725@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alex Williamson commit e73638e55f861758d49f14d7bb5dba3035981cd7 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 that the virq_disabled and bardirty flags are relocated to fill an existing hole in the structure. Bitfield justifications: has_dyn_msix: written only in vfio_pci_core_enable() pci_2_3: written only in vfio_pci_core_enable() reset_works: written only in vfio_pci_core_enable() extended_caps: written only in vfio_cap_len() under vfio_config_init() has_vga: written only in vfio_pci_core_enable() nointx: written only in vfio_pci_core_enable() needs_pm_restore: written only in vfio_pci_probe_power_state() disable_idle_d3: written only at .init in vfio_pci_core_init_dev() Dedicated storage units: virq_disabled: written by guest INTx command writes in vfio_basic_config_write() while the device is open bardirty: written by guest BAR writes in vfio_basic_config_write() while the device is open pm_intx_masked: written in the runtime-PM suspend path. pm_runtime_engaged: written by low-power feature entry/exit paths needs_reset: set in vfio_pci_core_disable() and cleared for devices in the set by vfio_pci_dev_set_try_reset() sriov_active: written by vfio_pci_core_sriov_configure() via sysfs sriov_numvfs while bound. Fixes: 9cd0f6d5cbb6 ("vfio/pci: Use bitfield for struct vfio_pci_core_device flags") 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/20260615191241.688297-4-alex.williamson@nvidia.com Signed-off-by: Alex Williamson Signed-off-by: Greg Kroah-Hartman --- include/linux/vfio_pci_core.h | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/include/linux/vfio_pci_core.h +++ b/include/linux/vfio_pci_core.h @@ -60,6 +60,9 @@ struct vfio_pci_core_device { struct pci_dev *pdev; void __iomem *barmap[PCI_STD_NUM_BARS]; bool bar_mmap_supported[PCI_STD_NUM_BARS]; + /* Flags modified at runtime - dedicated storage unit */ + bool virq_disabled; + bool bardirty; u8 *pci_config_map; u8 *vconfig; struct perm_bits *msi_perm; @@ -74,19 +77,19 @@ struct vfio_pci_core_device { u16 msix_size; u32 msix_offset; u32 rbar[7]; + /* Flags only modified on setup/release - bitfield ok */ bool has_dyn_msix:1; bool pci_2_3:1; - bool virq_disabled:1; bool reset_works:1; bool extended_caps:1; - bool bardirty:1; bool has_vga:1; - bool needs_reset:1; bool nointx:1; bool needs_pm_restore:1; - bool pm_intx_masked:1; - bool pm_runtime_engaged:1; bool disable_idle_d3:1; + /* Flags modified at runtime - dedicated storage unit */ + bool needs_reset; + bool pm_intx_masked; + bool pm_runtime_engaged; bool sriov_active; struct pci_saved_state *pci_saved_state; struct pci_saved_state *pm_save;