From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761455AbbA1ESs (ORCPT ); Tue, 27 Jan 2015 23:18:48 -0500 Received: from mail.kernel.org ([198.145.29.136]:38599 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1761436AbbA1ESo (ORCPT ); Tue, 27 Jan 2015 23:18:44 -0500 From: lizf@kernel.org To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, "Michael S. Tsirkin" , Amit Shah , Rusty Russell , Zefan Li Subject: [PATCH 3.4 055/177] virtio_pci: fix virtio spec compliance on restore Date: Wed, 28 Jan 2015 12:07:57 +0800 Message-Id: <1422418236-12852-110-git-send-email-lizf@kernel.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1422418050-12581-1-git-send-email-lizf@kernel.org> References: <1422418050-12581-1-git-send-email-lizf@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Michael S. Tsirkin" 3.4.106-rc1 review patch. If anyone has any objections, please let me know. ------------------ commit 6fbc198cf623944ab60a1db6d306a4d55cdd820d upstream. On restore, virtio pci does the following: + set features + init vqs etc - device can be used at this point! + set ACKNOWLEDGE,DRIVER and DRIVER_OK status bits This is in violation of the virtio spec, which requires the following order: - ACKNOWLEDGE - DRIVER - init vqs - DRIVER_OK This behaviour will break with hypervisors that assume spec compliant behaviour. It seems like a good idea to have this patch applied to stable branches to reduce the support butden for the hypervisors. Cc: Amit Shah Signed-off-by: Michael S. Tsirkin Signed-off-by: Rusty Russell Signed-off-by: Zefan Li --- drivers/virtio/virtio_pci.c | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c index 2e03d41..a41f264 100644 --- a/drivers/virtio/virtio_pci.c +++ b/drivers/virtio/virtio_pci.c @@ -745,6 +745,7 @@ static int virtio_pci_restore(struct device *dev) struct pci_dev *pci_dev = to_pci_dev(dev); struct virtio_pci_device *vp_dev = pci_get_drvdata(pci_dev); struct virtio_driver *drv; + unsigned status = 0; int ret; drv = container_of(vp_dev->vdev.dev.driver, @@ -755,14 +756,40 @@ static int virtio_pci_restore(struct device *dev) return ret; pci_set_master(pci_dev); + /* We always start by resetting the device, in case a previous + * driver messed it up. */ + vp_reset(&vp_dev->vdev); + + /* Acknowledge that we've seen the device. */ + status |= VIRTIO_CONFIG_S_ACKNOWLEDGE; + vp_set_status(&vp_dev->vdev, status); + + /* Maybe driver failed before freeze. + * Restore the failed status, for debugging. */ + status |= vp_dev->saved_status & VIRTIO_CONFIG_S_FAILED; + vp_set_status(&vp_dev->vdev, status); + + if (!drv) + return 0; + + /* We have a driver! */ + status |= VIRTIO_CONFIG_S_DRIVER; + vp_set_status(&vp_dev->vdev, status); + vp_finalize_features(&vp_dev->vdev); - if (drv && drv->restore) + if (drv->restore) { ret = drv->restore(&vp_dev->vdev); + if (ret) { + status |= VIRTIO_CONFIG_S_FAILED; + vp_set_status(&vp_dev->vdev, status); + return ret; + } + } /* Finally, tell the device we're all set */ - if (!ret) - vp_set_status(&vp_dev->vdev, vp_dev->saved_status); + status |= VIRTIO_CONFIG_S_DRIVER_OK; + vp_set_status(&vp_dev->vdev, status); return ret; } -- 1.9.1