From: Cornelia Huck <cohuck@redhat.com>
To: Tony Krowiak <akrowiak@linux.ibm.com>
Cc: linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, freude@linux.ibm.com,
borntraeger@de.ibm.com, mjrosato@linux.ibm.com,
pasic@linux.ibm.com, alex.williamson@redhat.com,
kwankhede@nvidia.com, fiuczy@linux.ibm.com,
frankja@linux.ibm.com, david@redhat.com, imbrenda@linux.ibm.com,
hca@linux.ibm.com, gor@linux.ibm.com,
kernel test robot <lkp@intel.com>
Subject: Re: [PATCH v10 04/16] s390/zcrypt: driver callback to indicate resource in use
Date: Thu, 17 Sep 2020 14:14:42 +0200 [thread overview]
Message-ID: <20200917141442.6e531799.cohuck@redhat.com> (raw)
In-Reply-To: <fe3ba715-8ea7-45df-4144-d1f5dec38a45@linux.ibm.com>
On Tue, 15 Sep 2020 15:32:35 -0400
Tony Krowiak <akrowiak@linux.ibm.com> wrote:
> On 9/14/20 11:29 AM, Cornelia Huck wrote:
> > On Fri, 21 Aug 2020 15:56:04 -0400
> > Tony Krowiak <akrowiak@linux.ibm.com> wrote:
> >
> >> Introduces a new driver callback to prevent a root user from unbinding
> >> an AP queue from its device driver if the queue is in use. The intent of
> >> this callback is to provide a driver with the means to prevent a root user
> >> from inadvertently taking a queue away from a matrix mdev and giving it to
> >> the host while it is assigned to the matrix mdev. The callback will
> >> be invoked whenever a change to the AP bus's sysfs apmask or aqmask
> >> attributes would result in one or more AP queues being removed from its
> >> driver. If the callback responds in the affirmative for any driver
> >> queried, the change to the apmask or aqmask will be rejected with a device
> >> in use error.
> >>
> >> For this patch, only non-default drivers will be queried. Currently,
> >> there is only one non-default driver, the vfio_ap device driver. The
> >> vfio_ap device driver facilitates pass-through of an AP queue to a
> >> guest. The idea here is that a guest may be administered by a different
> >> sysadmin than the host and we don't want AP resources to unexpectedly
> >> disappear from a guest's AP configuration (i.e., adapters, domains and
> >> control domains assigned to the matrix mdev). This will enforce the proper
> >> procedure for removing AP resources intended for guest usage which is to
> >> first unassign them from the matrix mdev, then unbind them from the
> >> vfio_ap device driver.
> >>
> >> Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
> >> Reported-by: kernel test robot <lkp@intel.com>
> > This looks a bit odd...
>
> I've removed all of those. These kernel test robot errors were flagged
> in the last series. The review comments from the robot suggested
> the reported-by, but I assume that was for patches intended to
> fix those errors, so I am removing these as per Christian's comments.
Yes, I think the Reported-by: mostly makes sense if you include a patch
to fix something on top.
>
> >
> >> ---
> >> drivers/s390/crypto/ap_bus.c | 148 ++++++++++++++++++++++++++++++++---
> >> drivers/s390/crypto/ap_bus.h | 4 +
> >> 2 files changed, 142 insertions(+), 10 deletions(-)
> >>
> > (...)
> >
> >> @@ -1107,12 +1118,70 @@ static ssize_t apmask_show(struct bus_type *bus, char *buf)
> >> return rc;
> >> }
> >>
> >> +static int __verify_card_reservations(struct device_driver *drv, void *data)
> >> +{
> >> + int rc = 0;
> >> + struct ap_driver *ap_drv = to_ap_drv(drv);
> >> + unsigned long *newapm = (unsigned long *)data;
> >> +
> >> + /*
> >> + * No need to verify whether the driver is using the queues if it is the
> >> + * default driver.
> >> + */
> >> + if (ap_drv->flags & AP_DRIVER_FLAG_DEFAULT)
> >> + return 0;
> >> +
> >> + /* The non-default driver's module must be loaded */
> >> + if (!try_module_get(drv->owner))
> >> + return 0;
> >> +
> >> + if (ap_drv->in_use)
> >> + if (ap_drv->in_use(newapm, ap_perms.aqm))
> >> + rc = -EADDRINUSE;
> > ISTR that Christian suggested -EBUSY in a past revision of this series?
> > I think that would be more appropriate.
>
> I went back and looked and sure enough, he did recommend that.
> You have a great memory! I didn't respond to that comment, so I
> must have missed it at the time.
>
> I personally prefer EADDRINUSE because I think it is more indicative
> of the reason an AP resource can not be assigned back to the host
> drivers is because it is in use by a guest or, at the very least, reserved
> for use by a guest (i.e., assigned to an mdev). To say it is busy implies
> that the device is busy performing encryption services which may or
> may not be true at a given moment. Even if so, that is not the reason
> for refusing to allow reassignment of the device.
I have a different understanding of these error codes: EADDRINUSE is
something used in the networking context when an actual address is
already used elsewhere. EBUSY is more of a generic error that indicates
that a certain resource is not free to perform the requested operation;
it does not necessarily mean that the resource is currently actively
doing something. Kind of when you get EBUSY when trying to eject
something another program holds a reference on: that other program
might not actually be doing anything, but it potentially could.
next prev parent reply other threads:[~2020-09-17 12:15 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-21 19:56 [PATCH v10 00/16] s390/vfio-ap: dynamic configuration support Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 01/16] s390/vfio-ap: add version vfio_ap module Tony Krowiak
2020-08-25 10:04 ` Cornelia Huck
2020-08-26 14:49 ` Tony Krowiak
2020-08-27 10:32 ` Cornelia Huck
2020-08-27 14:39 ` Tony Krowiak
2020-08-28 8:10 ` Cornelia Huck
2020-08-21 19:56 ` [PATCH v10 02/16] s390/vfio-ap: use new AP bus interface to search for queue devices Tony Krowiak
2020-08-25 10:13 ` Cornelia Huck
2020-08-27 14:24 ` Tony Krowiak
2020-08-28 8:13 ` Cornelia Huck
2020-08-28 15:10 ` Tony Krowiak
2020-09-25 2:11 ` Halil Pasic
2020-10-16 20:59 ` Tony Krowiak
2020-09-04 8:11 ` Christian Borntraeger
2020-09-08 18:54 ` Tony Krowiak
2020-09-25 2:27 ` Halil Pasic
2020-09-29 13:07 ` Tony Krowiak
2020-09-29 13:37 ` Halil Pasic
2020-09-29 20:57 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 03/16] s390/vfio-ap: manage link between queue struct and matrix mdev Tony Krowiak
2020-08-25 10:25 ` Cornelia Huck
2020-08-28 23:05 ` Tony Krowiak
2020-09-04 8:15 ` Christian Borntraeger
2020-09-08 19:03 ` Tony Krowiak
2020-09-25 7:58 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 04/16] s390/zcrypt: driver callback to indicate resource in use Tony Krowiak
2020-09-14 15:29 ` Cornelia Huck
2020-09-15 19:32 ` Tony Krowiak
2020-09-17 12:14 ` Cornelia Huck [this message]
2020-09-17 13:54 ` Tony Krowiak
2020-09-25 9:24 ` Halil Pasic
2020-09-29 13:59 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 05/16] s390/vfio-ap: implement in-use callback for vfio_ap driver Tony Krowiak
2020-09-14 15:31 ` Cornelia Huck
2020-09-25 9:29 ` Halil Pasic
2020-09-29 14:00 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 06/16] s390/vfio-ap: introduce shadow APCB Tony Krowiak
2020-09-17 14:22 ` Cornelia Huck
2020-09-18 17:03 ` Tony Krowiak
2020-09-26 1:38 ` Halil Pasic
2020-09-29 16:04 ` Tony Krowiak
2020-09-29 16:19 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 07/16] s390/vfio-ap: sysfs attribute to display the guest's matrix Tony Krowiak
2020-09-17 14:34 ` Cornelia Huck
2020-09-18 17:09 ` Tony Krowiak
2020-09-26 7:16 ` Halil Pasic
2020-09-29 21:00 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 08/16] s390/vfio-ap: filter matrix for unavailable queue devices Tony Krowiak
2020-09-26 8:24 ` Halil Pasic
2020-09-29 21:59 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 09/16] s390/vfio-ap: allow assignment of unavailable AP queues to mdev device Tony Krowiak
2020-09-26 23:49 ` Halil Pasic
2020-09-30 12:59 ` Tony Krowiak
2020-09-30 22:29 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 10/16] s390/vfio-ap: allow configuration of matrix mdev in use by a KVM guest Tony Krowiak
2020-09-27 0:03 ` Halil Pasic
2020-09-30 13:19 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 11/16] s390/vfio-ap: allow hot plug/unplug of AP resources using mdev device Tony Krowiak
2020-09-28 1:01 ` Halil Pasic
2020-10-05 16:24 ` Tony Krowiak
2020-10-05 18:30 ` Halil Pasic
2020-10-05 21:48 ` Tony Krowiak
2020-10-05 23:05 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 12/16] s390/zcrypt: Notify driver on config changed and scan complete callbacks Tony Krowiak
2020-09-27 1:39 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 13/16] s390/vfio-ap: handle host AP config change notification Tony Krowiak
2020-09-28 1:38 ` Halil Pasic
2020-10-12 20:53 ` Tony Krowiak
2020-10-12 21:27 ` Tony Krowiak
2020-08-21 19:56 ` [PATCH v10 14/16] s390/vfio-ap: handle AP bus scan completed notification Tony Krowiak
2020-09-28 2:11 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 15/16] s390/vfio-ap: handle probe/remove not due to host AP config changes Tony Krowiak
2020-09-28 2:45 ` Halil Pasic
2020-08-21 19:56 ` [PATCH v10 16/16] s390/vfio-ap: update docs to include dynamic config support Tony Krowiak
2020-08-25 10:45 ` Cornelia Huck
2020-08-31 18:34 ` Tony Krowiak
2020-09-28 2:48 ` Halil Pasic
2020-10-16 16:36 ` Tony Krowiak
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