From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941854AbdAIXEM (ORCPT ); Mon, 9 Jan 2017 18:04:12 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43608 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751982AbdAIXEH (ORCPT ); Mon, 9 Jan 2017 18:04:07 -0500 Date: Tue, 10 Jan 2017 01:04:06 +0200 From: "Michael S. Tsirkin" To: Cao jin Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, qemu-devel@nongnu.org, izumi.taku@jp.fujitsu.com, alex.williamson@redhat.com Subject: Re: [PATCH v2] vfio/pci: Support error recovery Message-ID: <20170110005600-mutt-send-email-mst@kernel.org> References: <1483175736-17137-1-git-send-email-caoj.fnst@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1483175736-17137-1-git-send-email-caoj.fnst@cn.fujitsu.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Mon, 09 Jan 2017 23:04:08 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote: > Support serious device error recovery serious? > > Signed-off-by: Cao jin > --- > drivers/vfio/pci/vfio_pci.c | 70 +++++++++++++++++++++++++++++++++++-- > drivers/vfio/pci/vfio_pci_private.h | 2 ++ > 2 files changed, 70 insertions(+), 2 deletions(-) > > diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c > index 712a849..752af20 100644 > --- a/drivers/vfio/pci/vfio_pci.c > +++ b/drivers/vfio/pci/vfio_pci.c > @@ -534,6 +534,15 @@ static long vfio_pci_ioctl(void *device_data, > { > struct vfio_pci_device *vdev = device_data; > unsigned long minsz; > + int ret; > + > + if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS || > + cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) { > + ret = wait_for_completion_interruptible( > + &vdev->aer_completion); don't split it like that. > + if (ret) > + return ret; > + } > > if (cmd == VFIO_DEVICE_GET_INFO) { > struct vfio_device_info info; > @@ -953,6 +962,15 @@ static ssize_t vfio_pci_rw(void *device_data, char __user *buf, > { > unsigned int index = VFIO_PCI_OFFSET_TO_INDEX(*ppos); > struct vfio_pci_device *vdev = device_data; > + int ret; > + > + /* block all kinds of access during host recovery */ > + if (vdev->aer_recovering) { > + ret = wait_for_completion_interruptible( > + &vdev->aer_completion); > + if (ret) > + return ret; > + } > > if (index >= VFIO_PCI_NUM_REGIONS + vdev->num_regions) > return -EINVAL; > @@ -1117,6 +1135,7 @@ static int vfio_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id) > vdev->irq_type = VFIO_PCI_NUM_IRQS; > mutex_init(&vdev->igate); > spin_lock_init(&vdev->irqlock); > + init_completion(&vdev->aer_completion); > > ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev); > if (ret) { > @@ -1176,6 +1195,9 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev, > { > struct vfio_pci_device *vdev; > struct vfio_device *device; > + u32 uncor_status; > + unsigned int aer_cap_offset; > + int ret; > > device = vfio_device_get_from_dev(&pdev->dev); > if (device == NULL) > @@ -1187,10 +1209,29 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev, > return PCI_ERS_RESULT_DISCONNECT; > } > > + /* > + * get device's uncorrectable error status as soon as possible, should be "Get". > + * and signal it to user space. The later we read it, the possibility > + * the register value is mangled grows. > + */ > + aer_cap_offset = pci_find_ext_capability(vdev->pdev, PCI_EXT_CAP_ID_ERR); > + ret = pci_read_config_dword(vdev->pdev, aer_cap_offset + > + PCI_ERR_UNCOR_STATUS, &uncor_status); > + if (ret) > + return PCI_ERS_RESULT_DISCONNECT; > + > + pr_info("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed Pls drop this. > mutex_lock(&vdev->igate); > > - if (vdev->err_trigger) > - eventfd_signal(vdev->err_trigger, 1); > + vdev->aer_recovering = true; > + reinit_completion(&vdev->aer_completion); > + > + if (vdev->err_trigger && uncor_status) { > + pr_info("device %d signal uncor status 0x%x to user", > + pdev->devfn, uncor_status); > + /* signal uncorrectable error status to user space */ > + eventfd_signal(vdev->err_trigger, uncor_status); > + } > > mutex_unlock(&vdev->igate); > > @@ -1199,8 +1240,33 @@ static pci_ers_result_t vfio_pci_aer_err_detected(struct pci_dev *pdev, > return PCI_ERS_RESULT_CAN_RECOVER; > } > > +static void vfio_pci_aer_resume(struct pci_dev *pdev) > +{ > + struct vfio_pci_device *vdev; > + struct vfio_device *device; > + > + device = vfio_device_get_from_dev(&pdev->dev); > + if (device == NULL) > + return; > + > + vdev = vfio_device_data(device); > + if (vdev == NULL) { > + vfio_device_put(device); > + return; > + } > + > + mutex_lock(&vdev->igate); > + vdev->aer_recovering = false; > + mutex_unlock(&vdev->igate); > + > + complete_all(&vdev->aer_completion); > + > + vfio_device_put(device); > +} > + > static const struct pci_error_handlers vfio_err_handlers = { > .error_detected = vfio_pci_aer_err_detected, > + .resume = vfio_pci_aer_resume, > }; > > static struct pci_driver vfio_pci_driver = { > diff --git a/drivers/vfio/pci/vfio_pci_private.h b/drivers/vfio/pci/vfio_pci_private.h > index 8a7d546..ba8471f 100644 > --- a/drivers/vfio/pci/vfio_pci_private.h > +++ b/drivers/vfio/pci/vfio_pci_private.h > @@ -83,6 +83,8 @@ struct vfio_pci_device { > bool bardirty; > bool has_vga; > bool needs_reset; > + bool aer_recovering; > + struct completion aer_completion; > struct pci_saved_state *pci_saved_state; > int refcnt; > struct eventfd_ctx *err_trigger; > -- > 1.8.3.1 > > How about some explanation about what is going on here? All these changes seem racy since any number of errors can trigger at any time. -- MST