Re: [PATCH v10 13/16] s390/vfio-ap: handle host AP config change notification

From: Tony Krowiak
Date: Mon Oct 12 2020 - 16:53:22 EST

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On 9/27/20 9:38 PM, Halil Pasic wrote:

On Fri, 21 Aug 2020 15:56:13 -0400
Tony Krowiak <akrowiak@xxxxxxxxxxxxx> wrote:

Implements the driver callback invoked by the AP bus when the host
AP configuration has changed. Since this callback is invoked prior to
unbinding a device from its device driver, the vfio_ap driver will
respond by unplugging the AP adapters, domains and control domains
removed from the host's AP configuration from the guests using them.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reported-by: kernel test robot <lkp@xxxxxxxxx>

Looks reasonable, but shouldn't vfio_ap_mdev_remove_queue() already
have code that kicks the queue from the shadow at this stage?

I mean if the removal is for a reason different that host config change,
we wont update the guest_matrix or?

---
drivers/s390/crypto/vfio_ap_drv.c | 5 +-
drivers/s390/crypto/vfio_ap_ops.c | 147 ++++++++++++++++++++++++--
drivers/s390/crypto/vfio_ap_private.h | 7 +-
3 files changed, 146 insertions(+), 13 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_drv.c b/drivers/s390/crypto/vfio_ap_drv.c
index aae5b3d8e3fa..ea0a7603e886 100644
--- a/drivers/s390/crypto/vfio_ap_drv.c
+++ b/drivers/s390/crypto/vfio_ap_drv.c
@@ -115,9 +115,11 @@ static int vfio_ap_matrix_dev_create(void)
/* Fill in config info via PQAP(QCI), if available */
if (test_facility(12)) {
- ret = ap_qci(&matrix_dev->info);
+ ret = ap_qci(&matrix_dev->config_info);
if (ret)
goto matrix_alloc_err;
+ memcpy(&matrix_dev->config_info_prev, &matrix_dev->config_info,
+ sizeof(struct ap_config_info));
}
mutex_init(&matrix_dev->lock);
@@ -177,6 +179,7 @@ static int __init vfio_ap_init(void)
vfio_ap_drv.remove = vfio_ap_queue_dev_remove;
vfio_ap_drv.in_use = vfio_ap_mdev_resource_in_use;
vfio_ap_drv.ids = ap_queue_ids;
+ vfio_ap_drv.on_config_changed = vfio_ap_on_cfg_changed;
ret = ap_driver_register(&vfio_ap_drv, THIS_MODULE, VFIO_AP_DRV_NAME);
if (ret) {
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 2b01a8eb6ee7..e002d556abab 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -347,7 +347,9 @@ static int vfio_ap_mdev_create(struct kobject *kobj, struct mdev_device *mdev)
}
matrix_mdev->mdev = mdev;
- vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->matrix);
+ vfio_ap_matrix_init(&matrix_dev->config_info, &matrix_mdev->matrix);
+ vfio_ap_matrix_init(&matrix_dev->config_info,
+ &matrix_mdev->shadow_apcb);
hash_init(matrix_mdev->qtable);
mdev_set_drvdata(mdev, matrix_mdev);
matrix_mdev->pqap_hook.hook = handle_pqap;
@@ -526,8 +528,8 @@ static int vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,
* 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)) {
+ if (!test_bit_inv(apid, (unsigned long *)
+ matrix_dev->config_info.apm)) {
clear_bit_inv(apid, shadow_apcb->apm);
continue;
}
@@ -540,7 +542,7 @@ static int vfio_ap_mdev_filter_matrix(struct ap_matrix_mdev *matrix_mdev,
* guest's AP configuration
*/
if (!test_bit_inv(apqi, (unsigned long *)
- matrix_dev->info.aqm)) {
+ matrix_dev->config_info.aqm)) {
clear_bit_inv(apqi, shadow_apcb->aqm);
continue;
}
@@ -594,7 +596,7 @@ 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);
+ vfio_ap_matrix_init(&matrix_dev->config_info, &shadow_apcb);
napm = bitmap_weight(matrix_mdev->matrix.apm, AP_DEVICES);
naqm = bitmap_weight(matrix_mdev->matrix.aqm, AP_DOMAINS);
@@ -741,7 +743,7 @@ static bool vfio_ap_mdev_assign_apqis_4_apid(struct ap_matrix_mdev *matrix_mdev,
for_each_set_bit_inv(apqi, matrix_mdev->matrix.aqm, AP_DOMAINS) {
if (!test_bit_inv(apqi,
- (unsigned long *) matrix_dev->info.aqm))
+ (unsigned long *)matrix_dev->config_info.aqm))
clear_bit_inv(apqi, aqm);
apqn = AP_MKQID(apid, apqi);
@@ -764,7 +766,7 @@ static bool vfio_ap_mdev_assign_guest_apid(struct ap_matrix_mdev *matrix_mdev,
unsigned long apqi, apqn;
if (!vfio_ap_mdev_has_crycb(matrix_mdev) ||
- !test_bit_inv(apid, (unsigned long *)matrix_dev->info.apm))
+ !test_bit_inv(apid, (unsigned long *)matrix_dev->config_info.apm))
return false;
if (bitmap_empty(matrix_mdev->shadow_apcb.aqm, AP_DOMAINS))
@@ -931,8 +933,8 @@ static bool vfio_ap_mdev_assign_apids_4_apqi(struct ap_matrix_mdev *matrix_mdev,
bitmap_copy(apm, matrix_mdev->matrix.apm, AP_DEVICES);
for_each_set_bit_inv(apid, matrix_mdev->matrix.apm, AP_DEVICES) {
- if (!test_bit_inv(apid,
- (unsigned long *) matrix_dev->info.apm))
+ if (!test_bit_inv(apid, (unsigned long *)
+ matrix_dev->config_info.apm))
clear_bit_inv(apqi, apm);
apqn = AP_MKQID(apid, apqi);
@@ -955,7 +957,7 @@ static bool vfio_ap_mdev_assign_guest_apqi(struct ap_matrix_mdev *matrix_mdev,
unsigned long apid, apqn;
if (!vfio_ap_mdev_has_crycb(matrix_mdev) ||
- !test_bit_inv(apqi, (unsigned long *)matrix_dev->info.aqm))
+ !test_bit_inv(apqi, (unsigned long *)matrix_dev->config_info.aqm))
return false;
if (bitmap_empty(matrix_mdev->shadow_apcb.apm, AP_DEVICES))
@@ -1702,7 +1704,7 @@ int vfio_ap_mdev_probe_queue(struct ap_queue *queue)
void vfio_ap_mdev_remove_queue(struct ap_queue *queue)
{
struct vfio_ap_queue *q;
- int apid, apqi;
+ unsigned long apid, apqi;

Unrelated?

Yes, I'll remove it.

mutex_lock(&matrix_dev->lock);
q = dev_get_drvdata(&queue->ap_dev.device);
@@ -1727,3 +1729,126 @@ bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm)
return in_use;
}
+
+/**
+ * vfio_ap_mdev_unassign_apids
+ *
+ * @matrix_mdev: The matrix mediated device
+ *
+ * @aqm: A bitmap with 256 bits. Each bit in the map represents an APID from 0
+ * to 255 (with the leftmost bit corresponding to APID 0).
+ *
+ * Unassigns each APID specified in @aqm that is assigned to the shadow CRYCB
+ * of @matrix_mdev. Returns true if at least one APID is unassigned; otherwise,
+ * returns false.
+ */
+static bool vfio_ap_mdev_unassign_apids(struct ap_matrix_mdev *matrix_mdev,
+ unsigned long *apm_unassign)
+{
+ unsigned long apid;
+ bool unassigned = false;
+
+ /*
+ * If the matrix mdev is not in use by a KVM guest, return indicating
+ * that no APIDs have been unassigned.
+ */
+ if (!vfio_ap_mdev_has_crycb(matrix_mdev))
+ return false;
+
+ for_each_set_bit_inv(apid, apm_unassign, AP_DEVICES) {
+ unassigned |= vfio_ap_mdev_unassign_guest_apid(matrix_mdev,
+ apid);
+ }

I guess, we could accomplish the unassign with operations operating on
full bitmaps (without looping over bits), but I have no strong opinion
here.

+
+ return unassigned;
+}
+
+/**
+ * vfio_ap_mdev_unassign_apqis
+ *
+ * @matrix_mdev: The matrix mediated device
+ *
+ * @aqm: A bitmap with 256 bits. Each bit in the map represents an APQI from 0
+ * to 255 (with the leftmost bit corresponding to APQI 0).
+ *
+ * Unassigns each APQI specified in @aqm that is assigned to the shadow CRYCB
+ * of @matrix_mdev. Returns true if at least one APQI is unassigned; otherwise,
+ * returns false.
+ */
+static bool vfio_ap_mdev_unassign_apqis(struct ap_matrix_mdev *matrix_mdev,
+ unsigned long *aqm_unassign)
+{
+ unsigned long apqi;
+ bool unassigned = false;
+
+ /*
+ * If the matrix mdev is not in use by a KVM guest, return indicating
+ * that no APQIs have been unassigned.
+ */
+ if (!vfio_ap_mdev_has_crycb(matrix_mdev))
+ return false;
+
+ for_each_set_bit_inv(apqi, aqm_unassign, AP_DOMAINS) {
+ unassigned |= vfio_ap_mdev_unassign_guest_apqi(matrix_mdev,
+ apqi);
+ }
+
+ return unassigned;
+}
+
+void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
+ struct ap_config_info *old_config_info)
+{
+ bool unassigned;
+ int ap_remove, aq_remove;
+ struct ap_matrix_mdev *matrix_mdev;
+ DECLARE_BITMAP(apm_unassign, AP_DEVICES);
+ DECLARE_BITMAP(aqm_unassign, AP_DOMAINS);
+
+ unsigned long *cur_apm, *cur_aqm, *prev_apm, *prev_aqm;
+
+ if (matrix_dev->flags & AP_MATRIX_CFG_CHG) {
+ WARN_ONCE(1, "AP host configuration change already reported");
+ return;
+ }
+
+ memcpy(&matrix_dev->config_info, new_config_info,
+ sizeof(struct ap_config_info));
+ memcpy(&matrix_dev->config_info_prev, old_config_info,
+ sizeof(struct ap_config_info));
+
+ cur_apm = (unsigned long *)matrix_dev->config_info.apm;
+ cur_aqm = (unsigned long *)matrix_dev->config_info.aqm;
+ prev_apm = (unsigned long *)matrix_dev->config_info_prev.apm;
+ prev_aqm = (unsigned long *)matrix_dev->config_info_prev.aqm;
+
+ ap_remove = bitmap_andnot(apm_unassign, prev_apm, cur_apm, AP_DEVICES);
+ aq_remove = bitmap_andnot(aqm_unassign, prev_aqm, cur_aqm, AP_DOMAINS);
+
+ mutex_lock(&matrix_dev->lock);
+ matrix_dev->flags |= AP_MATRIX_CFG_CHG;
+
+ list_for_each_entry(matrix_mdev, &matrix_dev->mdev_list, node) {
+ if (!vfio_ap_mdev_has_crycb(matrix_mdev))
+ continue;
+
+ unassigned = false;
+
+ if (ap_remove)
+ if (bitmap_intersects(matrix_mdev->shadow_apcb.apm,
+ apm_unassign, AP_DEVICES))
+ if (vfio_ap_mdev_unassign_apids(matrix_mdev,
+ apm_unassign))

This can be done with a single "if".

if (A)
if (B)
if (C)
D;

should be equivalent with
if (A && B && C)
D;
and your wouldn't end up that deep indentation. It is a style thing,
so unless regulated by the official coding style, it is up to you :)

+ unassigned = true;
+ if (aq_remove)
+ if (bitmap_intersects(matrix_mdev->shadow_apcb.aqm,
+ aqm_unassign, AP_DOMAINS))
+ if (vfio_ap_mdev_unassign_apqis(matrix_mdev,
+ aqm_unassign))
+ unassigned = true;
+
+ if (unassigned)
+ vfio_ap_mdev_commit_shadow_apcb(matrix_mdev);
+ }
+ mutex_unlock(&matrix_dev->lock);
+}
diff --git a/drivers/s390/crypto/vfio_ap_private.h b/drivers/s390/crypto/vfio_ap_private.h
index 055bce6d45db..fc8629e28ad3 100644
--- a/drivers/s390/crypto/vfio_ap_private.h
+++ b/drivers/s390/crypto/vfio_ap_private.h
@@ -40,10 +40,13 @@
struct ap_matrix_dev {
struct device device;
atomic_t available_instances;
- struct ap_config_info info;
+ struct ap_config_info config_info;
+ struct ap_config_info config_info_prev;
struct list_head mdev_list;
struct mutex lock;
struct ap_driver *vfio_ap_drv;
+ #define AP_MATRIX_CFG_CHG (1UL << 0)
+ unsigned long flags;
};
extern struct ap_matrix_dev *matrix_dev;
@@ -108,5 +111,7 @@ int vfio_ap_mdev_probe_queue(struct ap_queue *queue);
void vfio_ap_mdev_remove_queue(struct ap_queue *queue);
bool vfio_ap_mdev_resource_in_use(unsigned long *apm, unsigned long *aqm);
+void vfio_ap_on_cfg_changed(struct ap_config_info *new_config_info,
+ struct ap_config_info *old_config_info);
#endif /* _VFIO_AP_PRIVATE_H_ */

Next message: Rustam Kovhaev: "Re: KASAN: use-after-free Read in btrfs_scan_one_device"
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Next in thread: Tony Krowiak: "Re: [PATCH v10 13/16] s390/vfio-ap: handle host AP config change notification"
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