From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S966835AbdAJLlG (ORCPT ); Tue, 10 Jan 2017 06:41:06 -0500 Received: from cn.fujitsu.com ([59.151.112.132]:48393 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1765453AbdAJLlD (ORCPT ); Tue, 10 Jan 2017 06:41:03 -0500 X-IronPort-AV: E=Sophos;i="5.22,518,1449504000"; d="scan'208";a="14639052" Subject: Re: [PATCH v2] vfio/pci: Support error recovery To: "Michael S. Tsirkin" References: <1483175736-17137-1-git-send-email-caoj.fnst@cn.fujitsu.com> <20170110005600-mutt-send-email-mst@kernel.org> CC: , , , , From: Cao jin Message-ID: <5874C989.9080504@cn.fujitsu.com> Date: Tue, 10 Jan 2017 19:46:17 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 MIME-Version: 1.0 In-Reply-To: <20170110005600-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.167.226.69] X-yoursite-MailScanner-ID: 5904247AD1CA.A72C5 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: caoj.fnst@cn.fujitsu.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/10/2017 07:04 AM, Michael S. Tsirkin wrote: > On Sat, Dec 31, 2016 at 05:15:36PM +0800, Cao jin wrote: >> Support serious device error recovery > > serious? > Sorry for my poor vocabulary if it confuses people. I wanted to express the meaning that: vfio-pci actually cannot do a real recovery for device even if it provides the callbacks, it relies on the user to do a effective(or word "serious"?) recovery. Welcome the amendment on the commit log. -- Sincerely, Cao jin >> >> 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. >