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This patch fixes a lockdep splat introduced by commit f21916ec4826
("s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated").
The lockdep splat only occurs when starting a Secure Execution guest.
Crypto virtualization (vfio_ap) is not yet supported for SE guests;
however, in order to avoid this problem when support becomes available,
this fix is being provided.
The circular locking dependency was introduced when the setting of the
masks in the guest's APCB was executed while holding the matrix_dev->lock.
While the lock is definitely needed to protect the setting/unsetting of the
matrix_mdev->kvm pointer, it is not necessarily critical for setting the
masks; so, the matrix_dev->lock will be released while the masks are being
set or cleared.
Keep in mind, however, that another process that takes the matrix_dev->lock
can get control while the masks in the guest's APCB are being set or
cleared as a result of the driver being notified that the KVM pointer
has been set or unset. This could result in invalid access to the
matrix_mdev->kvm pointer by the intervening process. To avoid this
scenario, two new fields are being added to the ap_matrix_mdev struct:
struct ap_matrix_mdev {
...
bool kvm_busy;
wait_queue_head_t wait_for_kvm;
...
};
The functions that handle notification that the KVM pointer value has
been set or cleared will set the kvm_busy flag to true until they are done
processing at which time they will set it to false and wake up the tasks on
the matrix_mdev->wait_for_kvm wait queue. Functions that require
access to matrix_mdev->kvm will sleep on the wait queue until they are
awakened at which time they can safely access the matrix_mdev->kvm
field.
Fixes: f21916ec4826 ("s390/vfio-ap: clean up vfio_ap resources when KVM pointer invalidated")
Cc: stable@vger.kernel.org
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
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The queues assigned to a matrix mediated device are currently reset when:
* The VFIO_DEVICE_RESET ioctl is invoked
* The mdev fd is closed by userspace (QEMU)
* The mdev is removed from sysfs.
Immediately after the reset of a queue, a call is made to disable
interrupts for the queue. This is entirely unnecessary because the reset of
a queue disables interrupts, so this will be removed.
Furthermore, vfio_ap_irq_disable() does an unconditional PQAP/AQIC which
can result in a specification exception (when the corresponding facility
is not available), so this is actually a bugfix.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
[pasic@linux.ibm.com: minor rework before merging]
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Fixes: ec89b55e3bce ("s390: ap: implement PAPQ AQIC interception in kernel")
Cc: <stable@vger.kernel.org>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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We register a AP PQAP instruction hook during the open
of the mediated device. And unregister it on release.
During the probe of the AP device, we allocate a vfio_ap_queue
structure to keep track of the information we need for the
PQAP/AQIC instruction interception.
In the AP PQAP instruction hook, if we receive a demand to
enable IRQs,
- we retrieve the vfio_ap_queue based on the APQN we receive
in REG1,
- we retrieve the page of the guest address, (NIB), from
register REG2
- we retrieve the mediated device to use the VFIO pinning
infrastructure to pin the page of the guest address,
- we retrieve the pointer to KVM to register the guest ISC
and retrieve the host ISC
- finaly we activate GISA
If we receive a demand to disable IRQs,
- we deactivate GISA
- unregister from the GIB
- unpin the NIB
When removing the AP device from the driver the device is
reseted and this process unregisters the GISA from the GIB,
and unpins the NIB address then we free the vfio_ap_queue
structure.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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To be able to use the VFIO interface to facilitate the
mediated device memory pinning/unpinning we need to register
a notifier for IOMMU.
While we will start to pin one guest page for the interrupt indicator
byte, this is still ok with ballooning as this page will never be
used by the guest virtio-balloon driver.
So the pinned page will never be freed. And even a broken guest does
so, that would not impact the host as the original page is still
in control by vfio.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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We prepare the interception of the PQAP/AQIC instruction for
the case the AQIC facility is enabled in the guest.
First of all we do not want to change existing behavior when
intercepting AP instructions without the SIE allowing the guest
to use AP instructions.
In this patch we only handle the AQIC interception allowed by
facility 65 which will be enabled when the complete interception
infrastructure will be present.
We add a callback inside the KVM arch structure for s390 for
a VFIO driver to handle a specific response to the PQAP
instruction with the AQIC command and only this command.
But we want to be able to return a correct answer to the guest
even there is no VFIO AP driver in the kernel.
Therefor, we inject the correct exceptions from inside KVM for the
case the callback is not initialized, which happens when the vfio_ap
driver is not loaded.
We do consider the responsibility of the driver to always initialize
the PQAP callback if it defines queues by initializing the CRYCB for
a guest.
If the callback has been setup we call it.
If not we setup an answer considering that no queue is available
for the guest when no callback has been setup.
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Harald Freudenberger <freude@linux.ibm.com>
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
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Libudev relies on having a subsystem link for non-root devices. To
avoid libudev (and potentially other userspace tools) choking on the
matrix device let us introduce a matrix bus and with it the matrix
bus subsytem. Also make the matrix device reside within the matrix
bus.
Doing this we remove the forced link from the matrix device to the
vfio_ap driver and the device_type we do not need anymore.
Since the associated matrix driver is not the vfio_ap driver any more,
we have to change the search for the devices on the vfio_ap driver in
the function vfio_ap_verify_queue_reserved.
Fixes: 1fde573413b5 ("s390: vfio-ap: base implementation of VFIO AP device driver")
Cc: stable@vger.kernel.org
Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
Reported-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
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Implements the open callback on the mediated matrix device.
The function registers a group notifier to receive notification
of the VFIO_GROUP_NOTIFY_SET_KVM event. When notified,
the vfio_ap device driver will get access to the guest's
kvm structure. The open callback must ensure that only one
mediated device shall be opened per guest.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Acked-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Tested-by: Pierre Morel <pmorel@linux.ibm.com>
Acked-by: Pierre Morel <pmorel@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20180925231641.4954-12-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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Registers the matrix device created by the VFIO AP device
driver with the VFIO mediated device framework.
Registering the matrix device will create the sysfs
structures needed to create mediated matrix devices
each of which will be used to configure the AP matrix
for a guest and connect it to the VFIO AP device driver.
Registering the matrix device with the VFIO mediated device
framework will create the following sysfs structures:
/sys/devices/vfio_ap/matrix/
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ create
To create a mediated device for the AP matrix device, write a UUID
to the create file:
uuidgen > create
A symbolic link to the mediated device's directory will be created in the
devices subdirectory named after the generated $uuid:
/sys/devices/vfio_ap/matrix/
...... [mdev_supported_types]
......... [vfio_ap-passthrough]
............ [devices]
............... [$uuid]
A symbolic link to the mediated device will also be created
in the vfio_ap matrix's directory:
/sys/devices/vfio_ap/matrix/[$uuid]
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Message-Id: <20180925231641.4954-6-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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Introduces a new AP device driver. This device driver
is built on the VFIO mediated device framework. The framework
provides sysfs interfaces that facilitate passthrough
access by guests to devices installed on the linux host.
The VFIO AP device driver will serve two purposes:
1. Provide the interfaces to reserve AP devices for exclusive
use by KVM guests. This is accomplished by unbinding the
devices to be reserved for guest usage from the zcrypt
device driver and binding them to the VFIO AP device driver.
2. Implements the functions, callbacks and sysfs attribute
interfaces required to create one or more VFIO mediated
devices each of which will be used to configure the AP
matrix for a guest and serve as a file descriptor
for facilitating communication between QEMU and the
VFIO AP device driver.
When the VFIO AP device driver is initialized:
* It registers with the AP bus for control of type 10 (CEX4
and newer) AP queue devices. This limitation was imposed
due to:
1. A desire to keep the code as simple as possible;
2. Some older models are no longer supported by the kernel
and others are getting close to end of service.
3. A lack of older systems on which to test older devices.
The probe and remove callbacks will be provided to support
the binding/unbinding of AP queue devices to/from the VFIO
AP device driver.
* Creates a matrix device, /sys/devices/vfio_ap/matrix,
to serve as the parent of the mediated devices created, one
for each guest, and to hold the APQNs of the AP devices bound to
the VFIO AP device driver.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Reviewed-by: Halil Pasic <pasic@linux.ibm.com>
Tested-by: Michael Mueller <mimu@linux.ibm.com>
Tested-by: Farhan Ali <alifm@linux.ibm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Message-Id: <20180925231641.4954-5-akrowiak@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
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