lkml.org 
[lkml]   [2016]   [Nov]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH] vfio/pci: Support error recovery
    Date
    It is user space driver's or device-specific driver's(in guest) responsbility
    to do a serious recovery when error happened. Link-reset is one part of
    recovery, when pci device is assigned to VM via vfio, link-reset will do
    twice in host & guest separately, which will cause many trouble for a
    successful recovery, so, disable the vfio-pci's link-reset in aer driver
    in host, this is a keypoint for guest to do error recovery successfully.

    CC: alex.williamson@redhat.com
    CC: mst@redhat.com
    Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
    ---
    This is actually a RFC version(has debug lines left), and has minor changes in
    aer driver, so I think maybe it is better not to CC pci guys in this round.
    Later will do.

    drivers/pci/pcie/aer/aerdrv_core.c | 12 ++++++-
    drivers/vfio/pci/vfio_pci.c | 63 +++++++++++++++++++++++++++++++++++--
    drivers/vfio/pci/vfio_pci_private.h | 2 ++
    3 files changed, 74 insertions(+), 3 deletions(-)

    diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c
    index 521e39c..289fb8e 100644
    --- a/drivers/pci/pcie/aer/aerdrv_core.c
    +++ b/drivers/pci/pcie/aer/aerdrv_core.c
    @@ -496,7 +496,17 @@ static void do_recovery(struct pci_dev *dev, int severity)
    "error_detected",
    report_error_detected);

    - if (severity == AER_FATAL) {
    + /* vfio-pci as a general meta driver, it actually couldn't do any real
    + * recovery for device. It is user space driver, or device-specific
    + * driver in guest who should take care of the serious error recovery,
    + * link reset actually is one part of whole recovery. Doing reset_link
    + * in aer driver of host kernel for vfio-pci devices will cause many
    + * trouble for user space driver or guest's device-specific driver,
    + * for example: the serious recovery often need to read register in
    + * config space, but if register reading happens during link-resetting,
    + * it is quite possible to return invalid value like all F's, which
    + * will result in unpredictable error. */
    + if (severity == AER_FATAL && strcmp(dev->driver->name, "vfio-pci")) {
    result = reset_link(dev);
    if (result != PCI_ERS_RESULT_RECOVERED)
    goto failed;
    diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
    index 712a849..aefd751 100644
    --- a/drivers/vfio/pci/vfio_pci.c
    +++ b/drivers/vfio/pci/vfio_pci.c
    @@ -535,6 +535,15 @@ static long vfio_pci_ioctl(void *device_data,
    struct vfio_pci_device *vdev = device_data;
    unsigned long minsz;

    + if (vdev->aer_recovering && (cmd == VFIO_DEVICE_SET_IRQS ||
    + cmd == VFIO_DEVICE_RESET || cmd == VFIO_DEVICE_PCI_HOT_RESET)) {
    + int ret;
    + ret = wait_for_completion_interruptible(
    + &vdev->aer_error_completion);
    + if (ret)
    + return ret;
    + }
    +
    if (cmd == VFIO_DEVICE_GET_INFO) {
    struct vfio_device_info info;

    @@ -1117,6 +1126,7 @@ 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_error_completion);

    ret = vfio_add_group_dev(&pdev->dev, &vfio_pci_ops, vdev);
    if (ret) {
    @@ -1176,6 +1186,9 @@ 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 = 0;
    + unsigned int aer_cap_offset = 0;
    + int ret;

    device = vfio_device_get_from_dev(&pdev->dev);
    if (device == NULL)
    @@ -1187,10 +1200,30 @@ 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,
    + * 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_err("device %d got AER detect notification. uncorrectable error status = 0x%x\n", pdev->devfn, uncor_status);//to be removed
    mutex_lock(&vdev->igate);
    +
    + vdev->aer_recovering = true;
    + reinit_completion(&vdev->aer_error_completion);
    +
    + /* suspend config space access from user space,
    + * when vfio-pci's error recovery process is on */
    + pci_cfg_access_trylock(vdev->pdev);

    - if (vdev->err_trigger)
    - eventfd_signal(vdev->err_trigger, 1);
    + if (vdev->err_trigger && uncor_status) {
    + pr_err("device %d signal uncor status to user space", pdev->devfn);//may be removed
    + /* signal uncorrectable error status to user space */
    + eventfd_signal(vdev->err_trigger, uncor_status);
    + }

    mutex_unlock(&vdev->igate);

    @@ -1199,8 +1232,34 @@ 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;
    + }
    +
    + /* vfio-pci's error recovery is done, time to
    + * resume pci config space's accesses */
    + pci_cfg_access_unlock(vdev->pdev);
    +
    + vdev->aer_recovering = false;
    + complete_all(&vdev->aer_error_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..ebf1041 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_error_completion;
    struct pci_saved_state *pci_saved_state;
    int refcnt;
    struct eventfd_ctx *err_trigger;
    --
    1.8.3.1


    \
     
     \ /
      Last update: 2016-11-27 12:31    [W:2.797 / U:0.028 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site