From patchwork Thu Mar 16 12:41:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yi Liu X-Patchwork-Id: 13177540 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 3F465C7618E for ; Thu, 16 Mar 2023 12:42:29 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 5430A10E189; Thu, 16 Mar 2023 12:42:27 +0000 (UTC) Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by gabe.freedesktop.org (Postfix) with ESMTPS id 59FA910E19F; Thu, 16 Mar 2023 12:42:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1678970542; x=1710506542; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=AEvwWlClzX1rnKaz+xfqG9UfvXCn9+h9Ct8yRH9iLyU=; b=akyDYj/TrtfTsI6aGEhwaW5/Zc5HK1CSUpKocK7/JrHkaR3YRTpQqxmm OzcuPjAQt5yGtLyFXJaY8cGowDT+vaOf12c339uVKe2fmeUf+E1gZRW44 OUW6bOGOzDSEuBicRsiZlv8/OrZQnM2xcRo9O1EEP+cbxjxSRkgk/ICtG vYEAESCr9SHwd21FTybtdt5RZNygsngc00rl9rfUCneoaagH4TaGAW0tK zXIPvqRJTFe53nhNHi2Qjx2YGiOuVyrazxbP3GZFP9II33W9BFwSdxhev w438wx/nhrB7a/mN5OO/4L3yXE19dFHWqWG16RVrJFOqL9l4CSDpGwfyH g==; X-IronPort-AV: E=McAfee;i="6600,9927,10650"; a="321812059" X-IronPort-AV: E=Sophos;i="5.98,265,1673942400"; d="scan'208";a="321812059" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2023 05:42:09 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6600,9927,10650"; a="1009207887" X-IronPort-AV: E=Sophos;i="5.98,265,1673942400"; d="scan'208";a="1009207887" Received: from 984fee00a4c6.jf.intel.com ([10.165.58.231]) by fmsmga005.fm.intel.com with ESMTP; 16 Mar 2023 05:42:08 -0700 From: Yi Liu To: alex.williamson@redhat.com, jgg@nvidia.com, kevin.tian@intel.com Date: Thu, 16 Mar 2023 05:41:51 -0700 Message-Id: <20230316124156.12064-3-yi.l.liu@intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230316124156.12064-1-yi.l.liu@intel.com> References: <20230316124156.12064-1-yi.l.liu@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 2/7] vfio/pci: Only check ownership of opened devices in hot reset X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, yi.l.liu@intel.com, yi.y.sun@linux.intel.com, mjrosato@linux.ibm.com, kvm@vger.kernel.org, intel-gvt-dev@lists.freedesktop.org, joro@8bytes.org, cohuck@redhat.com, xudong.hao@intel.com, peterx@redhat.com, yan.y.zhao@intel.com, eric.auger@redhat.com, terrence.xu@intel.com, nicolinc@nvidia.com, shameerali.kolothum.thodi@huawei.com, suravee.suthikulpanit@amd.com, intel-gfx@lists.freedesktop.org, chao.p.peng@linux.intel.com, lulu@redhat.com, robin.murphy@arm.com, jasowang@redhat.com Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" If the affected device is not opened by any user, it's safe to reset it given it's not in use. Reviewed-by: Kevin Tian Signed-off-by: Yi Liu Reviewed-by: Jason Gunthorpe --- drivers/vfio/pci/vfio_pci_core.c | 14 +++++++++++--- include/uapi/linux/vfio.h | 8 ++++++++ 2 files changed, 19 insertions(+), 3 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c index 65bbef562268..5d745c9abf05 100644 --- a/drivers/vfio/pci/vfio_pci_core.c +++ b/drivers/vfio/pci/vfio_pci_core.c @@ -2429,10 +2429,18 @@ static int vfio_pci_dev_set_hot_reset(struct vfio_device_set *dev_set, list_for_each_entry(cur_vma, &dev_set->device_list, vdev.dev_set_list) { /* - * Test whether all the affected devices are contained by the - * set of groups provided by the user. + * Test whether all the affected devices can be reset by the + * user. + * + * Resetting an unused device (not opened) is safe, because + * dev_set->lock is held in hot reset path so this device + * cannot race being opened by another user simultaneously. + * + * Otherwise all opened devices in the dev_set must be + * contained by the set of groups provided by the user. */ - if (!vfio_dev_in_groups(cur_vma, groups)) { + if (cur_vma->vdev.open_count && + !vfio_dev_in_groups(cur_vma, groups)) { ret = -EINVAL; goto err_undo; } diff --git a/include/uapi/linux/vfio.h b/include/uapi/linux/vfio.h index 0552e8dcf0cb..f96e5689cffc 100644 --- a/include/uapi/linux/vfio.h +++ b/include/uapi/linux/vfio.h @@ -673,6 +673,14 @@ struct vfio_pci_hot_reset_info { * VFIO_DEVICE_PCI_HOT_RESET - _IOW(VFIO_TYPE, VFIO_BASE + 13, * struct vfio_pci_hot_reset) * + * Userspace requests hot reset for the devices it uses. Due to the + * underlying topology, multiple devices can be affected in the reset + * while some might be opened by another user. To avoid interference + * the calling user must ensure all affected devices, if opened, are + * owned by itself. + * + * The ownership is proved by an array of group fds. + * * Return: 0 on success, -errno on failure. */ struct vfio_pci_hot_reset {