From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Wed, 8 May 2019 11:52:03 +0200 From: Cornelia Huck Subject: Re: [PATCH v1 1/2] vfio-ccw: Set subchannel state STANDBY on open Message-ID: <20190508115203.5596e207.cohuck@redhat.com> In-Reply-To: <3a55983d-c304-ec7e-f53d-8380576b9a42@linux.ibm.com> References: <1557148270-19901-1-git-send-email-pmorel@linux.ibm.com> <1557148270-19901-2-git-send-email-pmorel@linux.ibm.com> <3a55983d-c304-ec7e-f53d-8380576b9a42@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: kvm-owner@vger.kernel.org List-Archive: List-Post: To: Farhan Ali Cc: Pierre Morel , pasic@linux.vnet.ibm.com, farman@linux.ibm.com, linux-s390@vger.kernel.org, kvm@vger.kernel.org List-ID: On Tue, 7 May 2019 15:44:54 -0400 Farhan Ali wrote: > On 05/06/2019 09:11 AM, Pierre Morel wrote: > > When no guest is associated with the mediated device, > > i.e. the mediated device is not opened, the state of > > the mediated device is VFIO_CCW_STATE_NOT_OPER. > > > > The subchannel enablement and the according setting to the > > VFIO_CCW_STATE_STANDBY state should only be done when all > > parts of the VFIO mediated device have been initialized > > i.e. after the mediated device has been successfully opened. > > > > Let's stay in VFIO_CCW_STATE_NOT_OPER until the mediated > > device has been opened. > > > > When the mediated device is closed, disable the sub channel > > by calling vfio_ccw_sch_quiesce() no reset needs to be done > > the mediated devce will be enable on next open. > > s/devce/device > > > > > Signed-off-by: Pierre Morel > > --- > > drivers/s390/cio/vfio_ccw_drv.c | 10 +--------- > > drivers/s390/cio/vfio_ccw_ops.c | 36 ++++++++++++++++++------------------ > > 2 files changed, 19 insertions(+), 27 deletions(-) > > (...) > > diff --git a/drivers/s390/cio/vfio_ccw_ops.c b/drivers/s390/cio/vfio_ccw_ops.c > > index 5eb6111..497419c 100644 > > --- a/drivers/s390/cio/vfio_ccw_ops.c > > +++ b/drivers/s390/cio/vfio_ccw_ops.c > > @@ -115,14 +115,10 @@ static int vfio_ccw_mdev_create(struct kobject *kobj, struct mdev_device *mdev) > > struct vfio_ccw_private *private = > > dev_get_drvdata(mdev_parent_dev(mdev)); > > > > - if (private->state == VFIO_CCW_STATE_NOT_OPER) > > - return -ENODEV; > > - > > if (atomic_dec_if_positive(&private->avail) < 0) > > return -EPERM; > > > > private->mdev = mdev; > > - private->state = VFIO_CCW_STATE_IDLE; > > > > return 0; > > } > > @@ -132,12 +128,7 @@ static int vfio_ccw_mdev_remove(struct mdev_device *mdev) > > struct vfio_ccw_private *private = > > dev_get_drvdata(mdev_parent_dev(mdev)); > > > > - if ((private->state != VFIO_CCW_STATE_NOT_OPER) && > > - (private->state != VFIO_CCW_STATE_STANDBY)) { > > - if (!vfio_ccw_sch_quiesce(private->sch)) > > - private->state = VFIO_CCW_STATE_STANDBY; > > - /* The state will be NOT_OPER on error. */ > > - } > > + vfio_ccw_sch_quiesce(private->sch); > > > > cp_free(&private->cp); > > private->mdev = NULL; > > @@ -151,6 +142,7 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev) > > struct vfio_ccw_private *private = > > dev_get_drvdata(mdev_parent_dev(mdev)); > > unsigned long events = VFIO_IOMMU_NOTIFY_DMA_UNMAP; > > + struct subchannel *sch = private->sch; > > int ret; > > > > private->nb.notifier_call = vfio_ccw_mdev_notifier; > > @@ -165,6 +157,20 @@ static int vfio_ccw_mdev_open(struct mdev_device *mdev) > > vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY, > > &private->nb); > > return ret; I think this "return ret;" needs to go into the if branch above it; otherwise, the code below won't be reached :) > > + > > + spin_lock_irq(private->sch->lock); > > + if (cio_enable_subchannel(sch, (u32)(unsigned long)sch)) > > + goto error; > > + > > + private->state = VFIO_CCW_STATE_STANDBY; > > I don't think we should set the state to STANDBY here, because with just > this patch applied, any VFIO_CCW_EVENT_IO_REQ will return an error (due > to fsm_io_error). > > It might be safe to set it to IDLE in this patch. Agreed, this should be IDLE; otherwise, I don't see how a device might move into IDLE state? (That change happens in the next patch anyway.) > > > > + spin_unlock_irq(sch->lock); > > + return 0; > > + > > +error: > > + spin_unlock_irq(sch->lock); > > + vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY, > > + &private->nb); > > + return -EFAULT; > > } > > > > static void vfio_ccw_mdev_release(struct mdev_device *mdev) > > @@ -173,20 +179,14 @@ static void vfio_ccw_mdev_release(struct mdev_device *mdev) > > dev_get_drvdata(mdev_parent_dev(mdev)); > > int i; > > > > - if ((private->state != VFIO_CCW_STATE_NOT_OPER) && > > - (private->state != VFIO_CCW_STATE_STANDBY)) { > > - if (!vfio_ccw_mdev_reset(mdev)) > > - private->state = VFIO_CCW_STATE_STANDBY; > > - /* The state will be NOT_OPER on error. */ > > - } > > - > > - cp_free(&private->cp); > > + vfio_ccw_sch_quiesce(private->sch); > > vfio_unregister_notifier(mdev_dev(mdev), VFIO_IOMMU_NOTIFY, > > &private->nb); > > > > for (i = 0; i < private->num_regions; i++) > > private->region[i].ops->release(private, &private->region[i]); > > > > + cp_free(&private->cp); I'm wondering why this cp_free is moved -- there should not be any activity related to it after quiesce, should there? > > private->num_regions = 0; > > kfree(private->region); > > private->region = NULL; > > >