Re: [PATCH v10 08/16] s390/vfio-ap: filter matrix for unavailable queue devices
From: Tony Krowiak
Date: Tue Sep 29 2020 - 17:59:55 EST
On 9/26/20 4:24 AM, Halil Pasic wrote:
On Fri, 21 Aug 2020 15:56:08 -0400
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:
Even though APQNs for queues that are not in the host's AP configuration
may be assigned to a matrix mdev, we do not want to set bits in the guest's
APCB for APQNs that do not reference AP queue devices bound to the vfio_ap
device driver. Ideally, it would be great if such APQNs could be filtered
out before setting the bits in the guest's APCB; however, the architecture
precludes filtering individual APQNs. Consequently, either the APID or APQI
must be filtered.
This patch introduces code to filter the APIDs or APQIs assigned to the
matrix mdev's AP configuration before assigning them to the guest's AP
configuration (i.e., APCB). We'll start by filtering the APIDs:
If an APQN assigned to the matrix mdev's AP configuration does not
reference a queue device bound to the vfio_ap device driver, the APID
will be filtered out (i.e., not assigned to the guest's APCB).
If every APID assigned to the matrix mdev is filtered out, then we'll try
filtering the APQI's:
If an APQN assigned to the matrix mdev's AP configuration does not
reference a queue device bound to the vfio_ap device driver, the APQI
will be filtered out (i.e., not assigned to the guest's APCB).
In any case, if after filtering either the APIDs or APQIs there are any
APQNs that can be assigned to the guest's APCB, they will be assigned and
the CRYCB will be hot plugged into the guest.
Example
=======
APQNs bound to vfio_ap device driver:
04.0004
04.0047
04.0054
05.0005
05.0047
05.0054
Assignments to matrix mdev:
APIDs APQIs -> APQNs
04 0004 04.0004
05 0005 04.0005
0047 04.0047
0054 04.0054
05.0004
05.0005
05.0047
04.0054
Filter APIDs:
APID 04 will be filtered because APQN 04.0005 is not bound.
APID 05 will be filtered because APQN 05.0004 is not bound.
APQNs remaining: None
Filter APQIs:
APQI 04 will be filtered because APQN 05.0004 is not bound.
APQI 05 will be filtered because APQN 04.0005 is not bound.
APQNs remaining: 04.0047, 04.0054, 05.0047, 05.0054
APQNs 04.0047, 04.0054, 05.0047, 05.0054 will be assigned to the CRYCB and
hot plugged into the KVM guest.
I find this logic where we first do one strategy, and if nothing remains
do the other strategy a little confusing. I will ramble on about it some
more in the code.
Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
---
drivers/s390/crypto/vfio_ap_ops.c | 159 +++++++++++++++++++++++++++++-
1 file changed, 155 insertions(+), 4 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 30bf23734af6..eaf4e9eab6cb 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -326,7 +326,7 @@ static bool vfio_ap_mdev_has_crycb(struct ap_matrix_mdev *matrix_mdev)
return (matrix_mdev->kvm && matrix_mdev->kvm->arch.crypto.crycbd);
}
-static void vfio_ap_mdev_commit_crycb(struct ap_matrix_mdev *matrix_mdev)
+static void vfio_ap_mdev_commit_shadow_apcb(struct ap_matrix_mdev *matrix_mdev)
{
kvm_arch_crypto_set_masks(matrix_mdev->kvm,
matrix_mdev->shadow_apcb.apm,
@@ -597,6 +597,157 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev,
return 0;
}
+/**
+ * vfio_ap_mdev_filter_matrix
+ *
+ * Filter APQNs assigned to the matrix mdev that do not reference an AP queue
+ * device bound to the vfio_ap device driver.
+ *
+ * @matrix_mdev: the matrix mdev whose AP configuration is to be filtered
+ * @shadow_apcb: the shadow of the KVM guest's APCB (contains AP configuration
+ * for guest)
+ * @filter_apids: boolean value indicating whether the APQNs shall be filtered
+ * by APID (true) or by APQI (false).
+ *
+ * Returns the number of APQNs remaining after filtering is complete.
+ */
+static int vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,
+ struct ap_matrix *shadow_apcb,
+ bool filter_apids)
+{
+ unsigned long apid, apqi, apqn;
+
+ memcpy(shadow_apcb, &matrix_mdev->matrix, sizeof(*shadow_apcb));
+
+ for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
+ /*
+ * If the APID is not assigned to the host AP configuration,
+ * we can not assign it to the guest's AP configuration
+ */
+ if (!test_bit_inv(apid,
+ (unsigned long *)matrix_dev->info.apm)) {
The patch description and the code seem to be out of sync. Here you do
some filtering based on the host's AP config info read at module read at
module initialization time.
+ clear_bit_inv(apid, shadow_apcb->apm);
+ continue;
+ }
+
+ for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm,
+ AP_DOMAINS) {
+ /*
+ * If the APQI is not assigned to the host AP
+ * configuration, then it can not be assigned to the
+ * guest's AP configuration
+ */
+ if (!test_bit_inv(apqi, (unsigned long *)
+ matrix_dev->info.aqm)) {
+ clear_bit_inv(apqi, shadow_apcb->aqm);
+ continue;
+ }
+
+ /*
+ * If the APQN is not bound to the vfio_ap device
+ * driver, then we can't assign it to the guest's
+ * AP configuration. The AP architecture won't
+ * allow filtering of a single APQN, so if we're
+ * filtering APIDs, then filter the APID; otherwise,
+ * filter the APQI.
+ */
+ apqn = AP_MKQID(apid, apqi);
+ if (!vfio_ap_get_queue(apqn)) {
Is this really gonna give NULL if the queue is not bound to vfio-ap? I
don't think so. This will get NULL if the queue is not known to the AP
bus, or has no driver-data assigned. In the current state it should give
you non-NULL if another driver has the queue, and maintains it's own
driver specific data in drvdata.
It will not give you a NULL if the zcrypt driver has the queue because
no zcrypt driver sets any drvdata. You do bring up a good point though
because there is no guarantee that another driver will never set
the driver data for a queue device. Consequently, I will be changing the
vfio_ap_get_queue(apqn) function to check the driver associated with
the device and return NULL if it is not the vfio_ap driver.
+ if (filter_apids)
+ clear_bit_inv(apid, shadow_apcb->apm);
+ else
+ clear_bit_inv(apqi, shadow_apcb->aqm);
+ break;
+ }
+ }
+
+ /*
+ * If we're filtering APQIs and all of them have been filtered,
+ * there's no need to continue filtering.
+ */
+ if (!filter_apids)
+ if (bitmap_empty(shadow_apcb->aqm, AP_DOMAINS))
+ break;
+ }
+
+ return bitmap_weight(shadow_apcb->apm, AP_DEVICES) *
+ bitmap_weight(shadow_apcb->aqm, AP_DOMAINS);
+}
+
+/**
+ * vfio_ap_mdev_config_shadow_apcb
+ *
+ * Configure the shadow of a KVM guest's APCB specifying the adapters, domains
+ * and control domains to be assigned to the guest. The shadow APCB will be
+ * configured after filtering the APQNs assigned to the matrix mdev that do not
+ * reference a queue device bound to the vfio_ap device driver.
+ *
+ * @matrix_mdev: the matrix mdev whose shadow APCB is to be configured.
+ *
+ * Returns true if the shadow APCB contents have been changed; otherwise,
+ * returns false.
+ */
+static bool vfio_ap_mdev_config_shadow_apcb(struct ap_matrix_mdev *matrix_mdev)
+{
+ int napm, naqm;
+ struct ap_matrix shadow_apcb;
+
+ vfio_ap_matrix_init(&matrix_dev->info, &shadow_apcb);
+ napm = bitmap_weight(matrix_mdev->matrix.apm, AP_DEVICES);
+ naqm = bitmap_weight(matrix_mdev->matrix.aqm, AP_DOMAINS);
+
+ /*
+ * If there are no APIDs or no APQIs assigned to the matrix mdev,
+ * then no APQNs shall be assigned to the guest CRYCB.
+ */
+ if ((napm != 0) || (naqm != 0)) {
+ /*
+ * Filter the APIDs assigned to the matrix mdev for APQNs that
+ * do not reference an AP queue device bound to the driver.
+ */
+ napm = vfio_ap_mdev_filter_matrix(matrix_mdev, &shadow_apcb,
+ true);
+ /*
+ * If there are no APQNs that can be assigned to the guest's
+ * CRYCB after filtering, then try filtering the APQIs.
+ */
+ if (napm == 0) {
When do we expect this to happen? Currently we don't assign queues that
are not bound to us, and we have ->in_use() that inhibits disappearance
of queues due to re-partitioning.
This will happen when domains are over-provisioned for a matrix
mdev. Suppose the following APQNs are assigned to the matrix
mdev:
00.0000
00.0004
00.0047
If queue 00.0047 is not bound to the vfio_ap device driver, then
the filtering code will filter APID 00.
Is your objection that this patch occurs prior to the
patch that implements over-provisioning? I guess your confusion
makes sense given over-provisioning is not introduced until after
this patch. Maybe I should re-order these to patches.
So what we are left with is queue becomes unavailable to the host
because of a config change, and maybe manual unbind -- not sure about
that.
A queue can be removed from the vfio_ap device driver for the
following reasons:
1. The apmask or aqmask change can result in a queue device
being unbound from vfio_ap.
2. A queue device can be manually unbound from vfio_ap.
3. A queue device can be unbound due to dynamic deconfiguration of
the adapter via the SE or SCLP Deconfigure Adjunct Processor
command (i.e., a configuration change)
Now if matrix_dev->info was to reflect the config the bus acts by, which
seems to the idea behind patch 12 we could react accordingly (if the
domain is gone filter aqm).
That is handled in patch 13 which is the callback that handles the
notification introduced in patch 12. That patch does not use this
filtering code, however.
I mean, the purpose of this callback seems to be getting us out of
trouble when domains are missing across all cards (i.e. some domains
were assigned away from us on the lower level).
Or am I missing something?
I think you are missing the fact that there are other reasons
why a queue device may not be bound to vfio_ap (see reasons
above).
+ naqm = vfio_ap_mdev_filter_matrix(matrix_mdev,
+ &shadow_apcb, false);
+
+ /*
+ * If there are no APQNs that can be assigned to the
+ * matrix mdev after filtering the APQIs, then no APQNs
+ * shall be assigned to the guest's CRYCB.
+ */
+ if (naqm == 0) {
+ bitmap_clear(shadow_apcb.apm, 0, AP_DEVICES);
+ bitmap_clear(shadow_apcb.aqm, 0, AP_DOMAINS);
+ }
+ }
+ }
+
+ /*
+ * If the guest's AP configuration has not changed, then return
+ * indicating such.
+ */
+ if (bitmap_equal(matrix_mdev->shadow_apcb.apm, shadow_apcb.apm,
+ AP_DEVICES) &&
+ bitmap_equal(matrix_mdev->shadow_apcb.aqm, shadow_apcb.aqm,
+ AP_DOMAINS) &&
+ bitmap_equal(matrix_mdev->shadow_apcb.adm, shadow_apcb.adm,
+ AP_DOMAINS))
+ return false;
+
+ /*
+ * Copy the changes to the guest's CRYCB, then return indicating that
+ * the guest's AP configuration has changed.
+ */
+ memcpy(&matrix_mdev->shadow_apcb, &shadow_apcb, sizeof(shadow_apcb));
+
+ return true;
+}
+
enum qlink_type {
LINK_APID,
LINK_APQI,
@@ -1284,9 +1435,8 @@ static int vfio_ap_mdev_group_notifier(struct notifier_block *nb,
if (!vfio_ap_mdev_has_crycb(matrix_mdev))
return NOTIFY_DONE;
- memcpy(&matrix_mdev->shadow_apcb, &matrix_mdev->matrix,
- sizeof(matrix_mdev->shadow_apcb));
- vfio_ap_mdev_commit_crycb(matrix_mdev);
+ if (vfio_ap_mdev_config_shadow_apcb(matrix_mdev))
+ vfio_ap_mdev_commit_shadow_apcb(matrix_mdev);
return NOTIFY_OK;
}
@@ -1396,6 +1546,7 @@ static void vfio_ap_mdev_release(struct mdev_device *mdev)
mutex_lock(&matrix_dev->lock);
if (matrix_mdev->kvm) {
kvm_arch_crypto_clear_masks(matrix_mdev->kvm);
+ vfio_ap_matrix_clear_masks(&matrix_mdev->shadow_apcb);
matrix_mdev->kvm->arch.crypto.pqap_hook = NULL;
vfio_ap_mdev_reset_queues(mdev);
kvm_put_kvm(matrix_mdev->kvm);