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Message-ID: <5874C989.9080504@cn.fujitsu.com>
Date: Tue, 10 Jan 2017 19:46:17 +0800
From: Cao jin <caoj.fnst@...fujitsu.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
CC: <linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>,
<qemu-devel@...gnu.org>, <izumi.taku@...fujitsu.com>,
<alex.williamson@...hat.com>
Subject: Re: [PATCH v2] vfio/pci: Support error recovery
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 <caoj.fnst@...fujitsu.com>
>> ---
>> 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.
>
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