Message ID | 20190130132212.7376-4-cohuck@redhat.com (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
Series | vfio-ccw: support hsch/csch (kernel part) | expand |
On 01/30/2019 08:22 AM, Cornelia Huck wrote: > Introduce a mutex to disallow concurrent reads or writes to the > I/O region. This makes sure that the data the kernel or user > space see is always consistent. > > The same mutex will be used to protect the async region as well. > > Signed-off-by: Cornelia Huck <cohuck@redhat.com> I keep wondering how the FSM could provide this, but I end up getting into chicken/egg rabbit holes. So, until my brain becomes wiser... Reviewed-by: Eric Farman <farman@linux.ibm.com> > --- > drivers/s390/cio/vfio_ccw_drv.c | 3 +++ > drivers/s390/cio/vfio_ccw_ops.c | 28 +++++++++++++++++++--------- > drivers/s390/cio/vfio_ccw_private.h | 2 ++ > 3 files changed, 24 insertions(+), 9 deletions(-) > > diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c > index 0b3b9de45c60..5ea0da1dd954 100644 > --- a/drivers/s390/cio/vfio_ccw_drv.c > +++ b/drivers/s390/cio/vfio_ccw_drv.c > @@ -84,7 +84,9 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) > if (is_final) > cp_free(&private->cp); > } > + mutex_lock(&private->io_mutex); > memcpy(private->io_region->irb_area, irb, sizeof(*irb)); > + mutex_unlock(&private->io_mutex); > > if (private->io_trigger) > eventfd_signal(private->io_trigger, 1); > @@ -129,6 +131,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) > > private->sch = sch; > dev_set_drvdata(&sch->dev, private); > + mutex_init(&private->io_mutex); > > spin_lock_irq(sch->lock); > private->state = VFIO_CCW_STATE_NOT_OPER; > diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c > index 3fdcc6dfe0bf..025c8a832bc8 100644 > --- a/drivers/s390/cio/vfio_ccw_ops.c > +++ b/drivers/s390/cio/vfio_ccw_ops.c > @@ -169,16 +169,20 @@ static ssize_t vfio_ccw_mdev_read(struct mdev_device *mdev, > { > struct vfio_ccw_private *private; > struct ccw_io_region *region; > + int ret; > > if (*ppos + count > sizeof(*region)) > return -EINVAL; > > private = dev_get_drvdata(mdev_parent_dev(mdev)); > + mutex_lock(&private->io_mutex); > region = private->io_region; > if (copy_to_user(buf, (void *)region + *ppos, count)) > - return -EFAULT; > - > - return count; > + ret = -EFAULT; > + else > + ret = count; > + mutex_unlock(&private->io_mutex); > + return ret; > } > > static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, > @@ -188,23 +192,29 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, > { > struct vfio_ccw_private *private; > struct ccw_io_region *region; > + int ret; > > if (*ppos + count > sizeof(*region)) > return -EINVAL; > > private = dev_get_drvdata(mdev_parent_dev(mdev)); > + if (!mutex_trylock(&private->io_mutex)) > + return -EAGAIN; > > region = private->io_region; > - if (copy_from_user((void *)region + *ppos, buf, count)) > - return -EFAULT; > + if (copy_from_user((void *)region + *ppos, buf, count)) { > + ret = -EFAULT; > + goto out_unlock; > + } > > vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ); > - if (region->ret_code != 0) { > + if (region->ret_code != 0) > private->state = VFIO_CCW_STATE_IDLE; > - return region->ret_code; > - } > + ret = (region->ret_code != 0) ? region->ret_code : count; > > - return count; > +out_unlock: > + mutex_unlock(&private->io_mutex); > + return ret; > } > > static int vfio_ccw_mdev_get_device_info(struct vfio_device_info *info) > diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h > index 50c52efb4fcb..32173cbd838d 100644 > --- a/drivers/s390/cio/vfio_ccw_private.h > +++ b/drivers/s390/cio/vfio_ccw_private.h > @@ -28,6 +28,7 @@ > * @mdev: pointer to the mediated device > * @nb: notifier for vfio events > * @io_region: MMIO region to input/output I/O arguments/results > + * @io_mutex: protect against concurrent update of I/O regions > * @cp: channel program for the current I/O operation > * @irb: irb info received from interrupt > * @scsw: scsw info > @@ -42,6 +43,7 @@ struct vfio_ccw_private { > struct mdev_device *mdev; > struct notifier_block nb; > struct ccw_io_region *io_region; > + struct mutex io_mutex; > > struct channel_program cp; > struct irb irb; >
On Fri, 8 Feb 2019 16:26:06 -0500 Eric Farman <farman@linux.ibm.com> wrote: > On 01/30/2019 08:22 AM, Cornelia Huck wrote: > > Introduce a mutex to disallow concurrent reads or writes to the > > I/O region. This makes sure that the data the kernel or user > > space see is always consistent. > > > > The same mutex will be used to protect the async region as well. > > > > Signed-off-by: Cornelia Huck <cohuck@redhat.com> > > I keep wondering how the FSM could provide this, but I end up getting > into chicken/egg rabbit holes. Yes, if the fsm is able to provide this, it is probably not in an easy-to-understand way... > So, until my brain becomes wiser... > > Reviewed-by: Eric Farman <farman@linux.ibm.com> Thanks! > > > --- > > drivers/s390/cio/vfio_ccw_drv.c | 3 +++ > > drivers/s390/cio/vfio_ccw_ops.c | 28 +++++++++++++++++++--------- > > drivers/s390/cio/vfio_ccw_private.h | 2 ++ > > 3 files changed, 24 insertions(+), 9 deletions(-)
diff --git a/drivers/s390/cio/vfio_ccw_drv.c b/drivers/s390/cio/vfio_ccw_drv.c index 0b3b9de45c60..5ea0da1dd954 100644 --- a/drivers/s390/cio/vfio_ccw_drv.c +++ b/drivers/s390/cio/vfio_ccw_drv.c @@ -84,7 +84,9 @@ static void vfio_ccw_sch_io_todo(struct work_struct *work) if (is_final) cp_free(&private->cp); } + mutex_lock(&private->io_mutex); memcpy(private->io_region->irb_area, irb, sizeof(*irb)); + mutex_unlock(&private->io_mutex); if (private->io_trigger) eventfd_signal(private->io_trigger, 1); @@ -129,6 +131,7 @@ static int vfio_ccw_sch_probe(struct subchannel *sch) private->sch = sch; dev_set_drvdata(&sch->dev, private); + mutex_init(&private->io_mutex); spin_lock_irq(sch->lock); private->state = VFIO_CCW_STATE_NOT_OPER; diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c index 3fdcc6dfe0bf..025c8a832bc8 100644 --- a/drivers/s390/cio/vfio_ccw_ops.c +++ b/drivers/s390/cio/vfio_ccw_ops.c @@ -169,16 +169,20 @@ static ssize_t vfio_ccw_mdev_read(struct mdev_device *mdev, { struct vfio_ccw_private *private; struct ccw_io_region *region; + int ret; if (*ppos + count > sizeof(*region)) return -EINVAL; private = dev_get_drvdata(mdev_parent_dev(mdev)); + mutex_lock(&private->io_mutex); region = private->io_region; if (copy_to_user(buf, (void *)region + *ppos, count)) - return -EFAULT; - - return count; + ret = -EFAULT; + else + ret = count; + mutex_unlock(&private->io_mutex); + return ret; } static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, @@ -188,23 +192,29 @@ static ssize_t vfio_ccw_mdev_write(struct mdev_device *mdev, { struct vfio_ccw_private *private; struct ccw_io_region *region; + int ret; if (*ppos + count > sizeof(*region)) return -EINVAL; private = dev_get_drvdata(mdev_parent_dev(mdev)); + if (!mutex_trylock(&private->io_mutex)) + return -EAGAIN; region = private->io_region; - if (copy_from_user((void *)region + *ppos, buf, count)) - return -EFAULT; + if (copy_from_user((void *)region + *ppos, buf, count)) { + ret = -EFAULT; + goto out_unlock; + } vfio_ccw_fsm_event(private, VFIO_CCW_EVENT_IO_REQ); - if (region->ret_code != 0) { + if (region->ret_code != 0) private->state = VFIO_CCW_STATE_IDLE; - return region->ret_code; - } + ret = (region->ret_code != 0) ? region->ret_code : count; - return count; +out_unlock: + mutex_unlock(&private->io_mutex); + return ret; } static int vfio_ccw_mdev_get_device_info(struct vfio_device_info *info) diff --git a/drivers/s390/cio/vfio_ccw_private.h b/drivers/s390/cio/vfio_ccw_private.h index 50c52efb4fcb..32173cbd838d 100644 --- a/drivers/s390/cio/vfio_ccw_private.h +++ b/drivers/s390/cio/vfio_ccw_private.h @@ -28,6 +28,7 @@ * @mdev: pointer to the mediated device * @nb: notifier for vfio events * @io_region: MMIO region to input/output I/O arguments/results + * @io_mutex: protect against concurrent update of I/O regions * @cp: channel program for the current I/O operation * @irb: irb info received from interrupt * @scsw: scsw info @@ -42,6 +43,7 @@ struct vfio_ccw_private { struct mdev_device *mdev; struct notifier_block nb; struct ccw_io_region *io_region; + struct mutex io_mutex; struct channel_program cp; struct irb irb;
Introduce a mutex to disallow concurrent reads or writes to the I/O region. This makes sure that the data the kernel or user space see is always consistent. The same mutex will be used to protect the async region as well. Signed-off-by: Cornelia Huck <cohuck@redhat.com> --- drivers/s390/cio/vfio_ccw_drv.c | 3 +++ drivers/s390/cio/vfio_ccw_ops.c | 28 +++++++++++++++++++--------- drivers/s390/cio/vfio_ccw_private.h | 2 ++ 3 files changed, 24 insertions(+), 9 deletions(-)