From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v6 2/7] s390: ap: new vfio_ap_queue structure Date: Thu, 28 Mar 2019 14:06:46 +0100 Message-ID: <1b64ad7b-2a7c-b604-1adb-af400e7be516@linux.ibm.com> References: <1553265828-27823-1-git-send-email-pmorel@linux.ibm.com> <1553265828-27823-3-git-send-email-pmorel@linux.ibm.com> <169eec34-6397-3150-27df-9985c9e711b8@linux.ibm.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format="flowed" Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <169eec34-6397-3150-27df-9985c9e711b8@linux.ibm.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Archive: List-Post: To: Tony Krowiak , borntraeger@de.ibm.com Cc: alex.williamson@redhat.com, cohuck@redhat.com, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, frankja@linux.ibm.com, pasic@linux.ibm.com, david@redhat.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, freude@linux.ibm.com, mimu@linux.ibm.com List-ID: On 26/03/2019 21:45, Tony Krowiak wrote: > On 3/22/19 10:43 AM, Pierre Morel wrote: >> The AP interruptions are assigned on a queue basis and >> the GISA structure is handled on a VM basis, so that >> we need to add a structure we can retrieve from both side > > s/side/sides/ OK > >> holding the information we need to handle PQAP/AQIC interception >> and setup the GISA. > > s/setup/set up/ OK ...snip... >> + >> +static int vfio_ap_mdev_reset_queue(struct vfio_ap_queue *q) >> +{ >> +    struct ap_queue_status status; >> +    int retry = 1; >> + >> +    do { >> +        status = ap_zapq(q->apqn); >> +        switch (status.response_code) { >> +        case AP_RESPONSE_NORMAL: >> +            return 0; >> +        case AP_RESPONSE_RESET_IN_PROGRESS: >> +        case AP_RESPONSE_BUSY: >> +            msleep(20); >> +            break; >> +        default: >> +            /* things are really broken, give up */ > > I'm not sure things are necessarily broken. We could end up here if > the AP is removed from the configuration via the SE or SCLP Deconfigure > Adjunct Processor command. OK, but note that it is your original comment I just moved the function here ;) > >> +            return -EIO; >> +        } >> +    } while (retry--); >> + >> +    return -EBUSY; >> +} >> + >>   static void vfio_ap_matrix_init(struct ap_config_info *info, >>                   struct ap_matrix *matrix) >>   { >> @@ -45,6 +107,7 @@ static int vfio_ap_mdev_create(struct kobject >> *kobj, struct mdev_device *mdev) >>           return -ENOMEM; >>       } >> +    INIT_LIST_HEAD(&matrix_mdev->qlist); >>       vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix); >>       mdev_set_drvdata(mdev, matrix_mdev); >>       mutex_lock(&matrix_dev->lock); >> @@ -113,162 +176,189 @@ static struct attribute_group >> *vfio_ap_mdev_type_groups[] = { >>       NULL, >>   }; >> -struct vfio_ap_queue_reserved { >> -    unsigned long *apid; >> -    unsigned long *apqi; >> -    bool reserved; >> -}; >> +static void vfio_ap_free_queue(int apqn, struct ap_matrix_mdev >> *matrix_mdev) >> +{ >> +    struct vfio_ap_queue *q; >> + >> +    q = vfio_ap_get_queue(apqn, &matrix_mdev->qlist); >> +    if (!q) >> +        return; >> +    q->matrix_mdev = NULL; >> +    vfio_ap_mdev_reset_queue(q); > > I'm wondering if it's necessary to reset the queue here. The only time > a queue is used is when a guest using the mdev device is started. When > that guest is terminated, the fd for the mdev device is closed and the > mdev device's release callback is invoked. The release callback resets > the queues assigned to the mdev device. Is it really necessary to > reset the queue again when it is unassigned even if there would have > been no subsequent activity? Yes, it is necessary, the queue can be re-assigned to another guest later. Release will only be called when unbinding the queue from the driver. > >> +    list_move(&q->list, &matrix_dev->free_list); >> +} ...snip... >> +    for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) { >> +        apqn = AP_MKQID(apid, apqi); >> +        q = vfio_ap_find_queue(apqn); >> +        if (!q) { >> +            ret = -EADDRNOTAVAIL; >> +            goto rewind; >> +        } >> +        if (q->matrix_mdev) { > > If somebody assigns the same domain a second time, the assignment will > fail because the matrix_mdev will already have been associated with the > queue. I don't think it is appropriate to fail the assignment if the It is usual to report a failure in the case the operation requested has already be done. But we can do as you want. Any other opinion? > q->matrix_mdev is the same as the input matrix_mdev. This should be > changed to: > >     if (q->matrix_mdev != matrix_mdev) You surely want to say: add this, not change to this. ;) > Thanks for commenting, Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany