On Mon, Apr 12, 2021 at 04:03:02PM +0300, Max Gurtovoy wrote:
>
> On 4/12/2021 3:04 PM, Michael S. Tsirkin wrote:
> > On Mon, Apr 12, 2021 at 02:55:27PM +0300, Max Gurtovoy wrote:
> > > On 4/8/2021 6:56 PM, Michael S. Tsirkin wrote:
> > > > On Thu, Apr 08, 2021 at 12:56:52PM +0300, Max Gurtovoy wrote:
> > > > > On 4/8/2021 11:58 AM, Jason Wang wrote:
> > > > > > 在 2021/4/8 下午4:11, Max Gurtovoy 写道:
> > > > > > > The reset device operation, usually is an operation that might fail from
> > > > > > > various reasons. For example, the controller might be in a bad state and
> > > > > > > can't answer to any request. Usually, the paravirt SW based virtio
> > > > > > > devices always succeed in reset operation but this is not the case for
> > > > > > > HW based virtio devices.
> > > > > > I would like to know under what condition that the reset operation may
> > > > > > fail (except for the case of a bugg guest).
> > > > > The controller might not be ready or stuck. This is a real use case for many
> > > > > PCI devices.
> > > > >
> > > > > For real devices the FW might be in a bad state and it can happen also for
> > > > > paravirt device if you have a bug in the controller code or if you entered
> > > > > some error flow (Out of memory).
> > > > >
> > > > > You don't want to be stuck because of one bad device.
> > > > OK so maybe we can do more to detect the bad device.
> > > > Won't we get all 1's on a read in this case?
> > > No. how can we guarantee it ?
> > >
> > Well this is what you tend to get if e.g. you disable device memory.
> >
> > Anyway, you know about hardware, I don't ... It's not returning 0 after
> > reset as it should ... what does it return? Hopefully not random noise -
> > I don't think it's very practical to write a driver for a device that
> > starts doing that at random times ...
>
> The device may return 0x40 (NEEDS_RESET). It doesn't have to return all 1's.
>
> For paravirt devices, think of a situation that you can't allocate some
> internal buffers (malloc failed) and you want to wait for few seconds until
> the system memory will free some pages.
>
> So you may return NEEDS_RESET that indicates some error state of the device.
> Once the system memory freed by other application for example, your internal
> virtio device malloc succeeded and you may return 0.
>
> In this case, you don't want to stall the other virtio devices to probe
> (they might be real HW devices that driven by the same driver), right ?
So the device is very busy then? Not sure it's smart to just assume
it's safe to free all memory allocated for it then ...
I guess the lesson is don't make device reset depend on malloc
of some memory?
>
> >
> > > >
> > > > > > > This commit is also a preparation for adding a timeout mechanism for
> > > > > > > resetting virtio devices.
> > > > > > >
> > > > > > > Signed-off-by: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
> > > > > > > ---
> > > > > > >
> > > > > > > changes from v1:
> > > > > > > - update virtio_ccw.c (Cornelia)
> > > > > > > - update virtio_uml.c
> > > > > > > - update mlxbf-tmfifo.c
> > > > > > Note that virtio driver may call reset, so you probably need to convert
> > > > > > them.
> > > > > I'm sure I understand.
> > > > >
> > > > > Convert to what ?
> > > > >
> > > > > Thanks.
> > > > >
> > > > > > Thanks
> > > > > >
> > > > > >
> > > > > > > ---
> > > > > > > arch/um/drivers/virtio_uml.c | 4 +++-
> > > > > > > drivers/platform/mellanox/mlxbf-tmfifo.c | 4 +++-
> > > > > > > drivers/remoteproc/remoteproc_virtio.c | 4 +++-
> > > > > > > drivers/s390/virtio/virtio_ccw.c | 9 ++++++---
> > > > > > > drivers/virtio/virtio.c | 22 +++++++++++++++-------
> > > > > > > drivers/virtio/virtio_mmio.c | 3 ++-
> > > > > > > drivers/virtio/virtio_pci_legacy.c | 4 +++-
> > > > > > > drivers/virtio/virtio_pci_modern.c | 3 ++-
> > > > > > > drivers/virtio/virtio_vdpa.c | 4 +++-
> > > > > > > include/linux/virtio_config.h | 5 +++--
> > > > > > > 10 files changed, 43 insertions(+), 19 deletions(-)
> > > > > > >
> > > > > > > diff --git a/arch/um/drivers/virtio_uml.c b/arch/um/drivers/virtio_uml.c
> > > > > > > index 91ddf74ca888..b6e66265ed32 100644
> > > > > > > --- a/arch/um/drivers/virtio_uml.c
> > > > > > > +++ b/arch/um/drivers/virtio_uml.c
> > > > > > > @@ -827,11 +827,13 @@ static void vu_set_status(struct virtio_device
> > > > > > > *vdev, u8 status)
> > > > > > > vu_dev->status = status;
> > > > > > > }
> > > > > > > -static void vu_reset(struct virtio_device *vdev)
> > > > > > > +static int vu_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct virtio_uml_device *vu_dev = to_virtio_uml_device(vdev);
> > > > > > > vu_dev->status = 0;
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > static void vu_del_vq(struct virtqueue *vq)
> > > > > > > diff --git a/drivers/platform/mellanox/mlxbf-tmfifo.c
> > > > > > > b/drivers/platform/mellanox/mlxbf-tmfifo.c
> > > > > > > index bbc4e71a16ff..c192b8ac5d9e 100644
> > > > > > > --- a/drivers/platform/mellanox/mlxbf-tmfifo.c
> > > > > > > +++ b/drivers/platform/mellanox/mlxbf-tmfifo.c
> > > > > > > @@ -980,11 +980,13 @@ static void
> > > > > > > mlxbf_tmfifo_virtio_set_status(struct virtio_device *vdev,
> > > > > > > }
> > > > > > > /* Reset the device. Not much here for now. */
> > > > > > > -static void mlxbf_tmfifo_virtio_reset(struct virtio_device *vdev)
> > > > > > > +static int mlxbf_tmfifo_virtio_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct mlxbf_tmfifo_vdev *tm_vdev = mlxbf_vdev_to_tmfifo(vdev);
> > > > > > > tm_vdev->status = 0;
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > /* Read the value of a configuration field. */
> > > > > > > diff --git a/drivers/remoteproc/remoteproc_virtio.c
> > > > > > > b/drivers/remoteproc/remoteproc_virtio.c
> > > > > > > index 0cc617f76068..ca9573c62c3d 100644
> > > > > > > --- a/drivers/remoteproc/remoteproc_virtio.c
> > > > > > > +++ b/drivers/remoteproc/remoteproc_virtio.c
> > > > > > > @@ -191,7 +191,7 @@ static void rproc_virtio_set_status(struct
> > > > > > > virtio_device *vdev, u8 status)
> > > > > > > dev_dbg(&vdev->dev, "status: %d\n", status);
> > > > > > > }
> > > > > > > -static void rproc_virtio_reset(struct virtio_device *vdev)
> > > > > > > +static int rproc_virtio_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
> > > > > > > struct fw_rsc_vdev *rsc;
> > > > > > > @@ -200,6 +200,8 @@ static void rproc_virtio_reset(struct
> > > > > > > virtio_device *vdev)
> > > > > > > rsc->status = 0;
> > > > > > > dev_dbg(&vdev->dev, "reset !\n");
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > /* provide the vdev features as retrieved from the firmware */
> > > > > > > diff --git a/drivers/s390/virtio/virtio_ccw.c
> > > > > > > b/drivers/s390/virtio/virtio_ccw.c
> > > > > > > index 54e686dca6de..52b32555e746 100644
> > > > > > > --- a/drivers/s390/virtio/virtio_ccw.c
> > > > > > > +++ b/drivers/s390/virtio/virtio_ccw.c
> > > > > > > @@ -732,14 +732,15 @@ static int virtio_ccw_find_vqs(struct
> > > > > > > virtio_device *vdev, unsigned nvqs,
> > > > > > > return ret;
> > > > > > > }
> > > > > > > -static void virtio_ccw_reset(struct virtio_device *vdev)
> > > > > > > +static int virtio_ccw_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct virtio_ccw_device *vcdev = to_vc_device(vdev);
> > > > > > > struct ccw1 *ccw;
> > > > > > > + int ret;
> > > > > > > ccw = ccw_device_dma_zalloc(vcdev->cdev, sizeof(*ccw));
> > > > > > > if (!ccw)
> > > > > > > - return;
> > > > > > > + return -ENOMEM;
> > > > > > > /* Zero status bits. */
> > > > > > > vcdev->dma_area->status = 0;
> > > > > > > @@ -749,8 +750,10 @@ static void virtio_ccw_reset(struct
> > > > > > > virtio_device *vdev)
> > > > > > > ccw->flags = 0;
> > > > > > > ccw->count = 0;
> > > > > > > ccw->cda = 0;
> > > > > > > - ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_RESET);
> > > > > > > + ret = ccw_io_helper(vcdev, ccw, VIRTIO_CCW_DOING_RESET);
> > > > > > > ccw_device_dma_free(vcdev->cdev, ccw, sizeof(*ccw));
> > > > > > > +
> > > > > > > + return ret;
> > > > > > > }
> > > > > > > static u64 virtio_ccw_get_features(struct virtio_device *vdev)
> > > > > > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
> > > > > > > index 4b15c00c0a0a..ddbfd5b5f3bd 100644
> > > > > > > --- a/drivers/virtio/virtio.c
> > > > > > > +++ b/drivers/virtio/virtio.c
> > > > > > > @@ -338,7 +338,7 @@ int register_virtio_device(struct virtio_device
> > > > > > > *dev)
> > > > > > > /* Assign a unique device index and hence name. */
> > > > > > > err = ida_simple_get(&virtio_index_ida, 0, 0, GFP_KERNEL);
> > > > > > > if (err < 0)
> > > > > > > - goto out;
> > > > > > > + goto out_err;
> > > > > > > dev->index = err;
> > > > > > > dev_set_name(&dev->dev, "virtio%u", dev->index);
> > > > > > > @@ -349,7 +349,9 @@ int register_virtio_device(struct virtio_device
> > > > > > > *dev)
> > > > > > > /* We always start by resetting the device, in case a previous
> > > > > > > * driver messed it up. This also tests that code path a
> > > > > > > little. */
> > > > > > > - dev->config->reset(dev);
> > > > > > > + err = dev->config->reset(dev);
> > > > > > > + if (err)
> > > > > > > + goto out_ida;
> > > > > > > /* Acknowledge that we've seen the device. */
> > > > > > > virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> > > > > > > @@ -362,10 +364,14 @@ int register_virtio_device(struct
> > > > > > > virtio_device *dev)
> > > > > > > */
> > > > > > > err = device_add(&dev->dev);
> > > > > > > if (err)
> > > > > > > - ida_simple_remove(&virtio_index_ida, dev->index);
> > > > > > > -out:
> > > > > > > - if (err)
> > > > > > > - virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> > > > > > > + goto out_ida;
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > +
> > > > > > > +out_ida:
> > > > > > > + ida_simple_remove(&virtio_index_ida, dev->index);
> > > > > > > +out_err:
> > > > > > > + virtio_add_status(dev, VIRTIO_CONFIG_S_FAILED);
> > > > > > > return err;
> > > > > > > }
> > > > > > > EXPORT_SYMBOL_GPL(register_virtio_device);
> > > > > > > @@ -408,7 +414,9 @@ int virtio_device_restore(struct virtio_device *dev)
> > > > > > > /* We always start by resetting the device, in case a previous
> > > > > > > * driver messed it up. */
> > > > > > > - dev->config->reset(dev);
> > > > > > > + ret = dev->config->reset(dev);
> > > > > > > + if (ret)
> > > > > > > + goto err;
> > > > > > > /* Acknowledge that we've seen the device. */
> > > > > > > virtio_add_status(dev, VIRTIO_CONFIG_S_ACKNOWLEDGE);
> > > > > > > diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> > > > > > > index 56128b9c46eb..12b8f048c48d 100644
> > > > > > > --- a/drivers/virtio/virtio_mmio.c
> > > > > > > +++ b/drivers/virtio/virtio_mmio.c
> > > > > > > @@ -256,12 +256,13 @@ static void vm_set_status(struct virtio_device
> > > > > > > *vdev, u8 status)
> > > > > > > writel(status, vm_dev->base + VIRTIO_MMIO_STATUS);
> > > > > > > }
> > > > > > > -static void vm_reset(struct virtio_device *vdev)
> > > > > > > +static int vm_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct virtio_mmio_device *vm_dev = to_virtio_mmio_device(vdev);
> > > > > > > /* 0 status means a reset. */
> > > > > > > writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > diff --git a/drivers/virtio/virtio_pci_legacy.c
> > > > > > > b/drivers/virtio/virtio_pci_legacy.c
> > > > > > > index d62e9835aeec..0b5d95e3efa1 100644
> > > > > > > --- a/drivers/virtio/virtio_pci_legacy.c
> > > > > > > +++ b/drivers/virtio/virtio_pci_legacy.c
> > > > > > > @@ -89,7 +89,7 @@ static void vp_set_status(struct virtio_device
> > > > > > > *vdev, u8 status)
> > > > > > > iowrite8(status, vp_dev->ioaddr + VIRTIO_PCI_STATUS);
> > > > > > > }
> > > > > > > -static void vp_reset(struct virtio_device *vdev)
> > > > > > > +static int vp_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > > > > > > /* 0 status means a reset. */
> > > > > > > @@ -99,6 +99,8 @@ static void vp_reset(struct virtio_device *vdev)
> > > > > > > ioread8(vp_dev->ioaddr + VIRTIO_PCI_STATUS);
> > > > > > > /* Flush pending VQ/configuration callbacks. */
> > > > > > > vp_synchronize_vectors(vdev);
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > static u16 vp_config_vector(struct virtio_pci_device *vp_dev,
> > > > > > > u16 vector)
> > > > > > > diff --git a/drivers/virtio/virtio_pci_modern.c
> > > > > > > b/drivers/virtio/virtio_pci_modern.c
> > > > > > > index fbd4ebc00eb6..cc3412a96a17 100644
> > > > > > > --- a/drivers/virtio/virtio_pci_modern.c
> > > > > > > +++ b/drivers/virtio/virtio_pci_modern.c
> > > > > > > @@ -158,7 +158,7 @@ static void vp_set_status(struct virtio_device
> > > > > > > *vdev, u8 status)
> > > > > > > vp_modern_set_status(&vp_dev->mdev, status);
> > > > > > > }
> > > > > > > -static void vp_reset(struct virtio_device *vdev)
> > > > > > > +static int vp_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct virtio_pci_device *vp_dev = to_vp_device(vdev);
> > > > > > > struct virtio_pci_modern_device *mdev = &vp_dev->mdev;
> > > > > > > @@ -174,6 +174,7 @@ static void vp_reset(struct virtio_device *vdev)
> > > > > > > msleep(1);
> > > > > > > /* Flush pending VQ/configuration callbacks. */
> > > > > > > vp_synchronize_vectors(vdev);
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > static u16 vp_config_vector(struct virtio_pci_device *vp_dev,
> > > > > > > u16 vector)
> > > > > > > diff --git a/drivers/virtio/virtio_vdpa.c b/drivers/virtio/virtio_vdpa.c
> > > > > > > index e28acf482e0c..5fd4e627a9b0 100644
> > > > > > > --- a/drivers/virtio/virtio_vdpa.c
> > > > > > > +++ b/drivers/virtio/virtio_vdpa.c
> > > > > > > @@ -97,11 +97,13 @@ static void virtio_vdpa_set_status(struct
> > > > > > > virtio_device *vdev, u8 status)
> > > > > > > return ops->set_status(vdpa, status);
> > > > > > > }
> > > > > > > -static void virtio_vdpa_reset(struct virtio_device *vdev)
> > > > > > > +static int virtio_vdpa_reset(struct virtio_device *vdev)
> > > > > > > {
> > > > > > > struct vdpa_device *vdpa = vd_get_vdpa(vdev);
> > > > > > > vdpa_reset(vdpa);
> > > > > > > +
> > > > > > > + return 0;
> > > > > > > }
> > > > > > > static bool virtio_vdpa_notify(struct virtqueue *vq)
> > > > > > > diff --git a/include/linux/virtio_config.h
> > > > > > > b/include/linux/virtio_config.h
> > > > > > > index 8519b3ae5d52..d2b0f1699a75 100644
> > > > > > > --- a/include/linux/virtio_config.h
> > > > > > > +++ b/include/linux/virtio_config.h
> > > > > > > @@ -44,9 +44,10 @@ struct virtio_shm_region {
> > > > > > > * status: the new status byte
> > > > > > > * @reset: reset the device
> > > > > > > * vdev: the virtio device
> > > > > > > - * After this, status and feature negotiation must be done again
> > > > > > > + * Upon success, status and feature negotiation must be done again
> > > > > > > * Device must not be reset from its vq/config callbacks, or in
> > > > > > > * parallel with being added/removed.
> > > > > > > + * Returns 0 on success or error status.
> > > > > > > * @find_vqs: find virtqueues and instantiate them.
> > > > > > > * vdev: the virtio_device
> > > > > > > * nvqs: the number of virtqueues to find
> > > > > > > @@ -82,7 +83,7 @@ struct virtio_config_ops {
> > > > > > > u32 (*generation)(struct virtio_device *vdev);
> > > > > > > u8 (*get_status)(struct virtio_device *vdev);
> > > > > > > void (*set_status)(struct virtio_device *vdev, u8 status);
> > > > > > > - void (*reset)(struct virtio_device *vdev);
> > > > > > > + int (*reset)(struct virtio_device *vdev);
> > > > > > > int (*find_vqs)(struct virtio_device *, unsigned nvqs,
> > > > > > > struct virtqueue *vqs[], vq_callback_t *callbacks[],
> > > > > > > const char * const names[], const bool *ctx,
