From: Tony Krowiak <akrowiak@linux.ibm.com>
Date: Wed, 16 Mar 2022 22:21:38 -0400
Subject: s390/vfio-ap: prepare for dynamic update of guest's APCB on
assign/unassign
Git-commit: 8ee13ad99337b0b6920e732d87c692d577335f15
Patch-mainline: v6.0-rc1
References: bsc#1205701
The functions backing the matrix mdev's sysfs attribute interfaces to
assign/unassign adapters, domains and control domains must take and
release the locks required to perform a dynamic update of a guest's APCB
in the proper order.
The proper order for taking the locks is:
matrix_dev->guests_lock => kvm->lock => matrix_dev->mdevs_lock
The proper order for releasing the locks is:
matrix_dev->mdevs_lock => kvm->lock => matrix_dev->guests_lock
Two new macros are introduced for this purpose: One to take the locks and
the other to release the locks. These macros will be used by the
assignment/unassignment functions to prepare for dynamic update of
the KVM guest's APCB.
Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
Acked-by: Joerg Roedel <jroedel@suse.de>
---
drivers/s390/crypto/vfio_ap_ops.c | 71 ++++++++++++++++++++++++++++++++-------
1 file changed, 59 insertions(+), 12 deletions(-)
diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 20f779dd8ab9..dcd36d427b86 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -77,6 +77,53 @@ static inline void release_update_locks_for_kvm(struct kvm *kvm)
mutex_unlock(&matrix_dev->guests_lock);
}
+/**
+ * get_update_locks_for_mdev: Acquire the locks required to dynamically update a
+ * KVM guest's APCB in the proper order.
+ *
+ * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
+ * configuration data to use to update a KVM guest's APCB.
+ *
+ * The proper locking order is:
+ * 1. matrix_dev->guests_lock: required to use the KVM pointer to update a KVM
+ * guest's APCB.
+ * 2. matrix_mdev->kvm->lock: required to update a guest's APCB
+ * 3. matrix_dev->mdevs_lock: required to access data stored in a matrix_mdev
+ *
+ * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
+ * lock will not be taken.
+ */
+static inline void get_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
+{
+ mutex_lock(&matrix_dev->guests_lock);
+ if (matrix_mdev && matrix_mdev->kvm)
+ mutex_lock(&matrix_mdev->kvm->lock);
+ mutex_lock(&matrix_dev->mdevs_lock);
+}
+
+/**
+ * release_update_locks_for_mdev: Release the locks used to dynamically update a
+ * KVM guest's APCB in the proper order.
+ *
+ * @matrix_mdev: a pointer to a struct ap_matrix_mdev object containing the AP
+ * configuration data to use to update a KVM guest's APCB.
+ *
+ * The proper unlocking order is:
+ * 1. matrix_dev->mdevs_lock
+ * 2. matrix_mdev->kvm->lock
+ * 3. matrix_dev->guests_lock
+ *
+ * Note: If @matrix_mdev is NULL or is not attached to a KVM guest, the KVM
+ * lock will not be released.
+ */
+static inline void release_update_locks_for_mdev(struct ap_matrix_mdev *matrix_mdev)
+{
+ mutex_unlock(&matrix_dev->mdevs_lock);
+ if (matrix_mdev && matrix_mdev->kvm)
+ mutex_unlock(&matrix_mdev->kvm->lock);
+ mutex_unlock(&matrix_dev->guests_lock);
+}
+
/**
* vfio_ap_mdev_get_queue - retrieve a queue with a specific APQN from a
* hash table of queues assigned to a matrix mdev
@@ -832,7 +879,7 @@ static ssize_t assign_adapter_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->mdevs_lock);
+ get_update_locks_for_mdev(matrix_mdev);
/* If the KVM guest is running, disallow assignment of adapter */
if (matrix_mdev->kvm) {
@@ -864,7 +911,7 @@ static ssize_t assign_adapter_store(struct device *dev,
matrix_mdev->matrix.aqm, matrix_mdev);
ret = count;
done:
- mutex_unlock(&matrix_dev->mdevs_lock);
+ release_update_locks_for_mdev(matrix_mdev);
return ret;
}
@@ -907,7 +954,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
unsigned long apid;
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->mdevs_lock);
+ get_update_locks_for_mdev(matrix_mdev);
/* If the KVM guest is running, disallow unassignment of adapter */
if (matrix_mdev->kvm) {
@@ -932,7 +979,7 @@ static ssize_t unassign_adapter_store(struct device *dev,
ret = count;
done:
- mutex_unlock(&matrix_dev->mdevs_lock);
+ release_update_locks_for_mdev(matrix_mdev);
return ret;
}
static DEVICE_ATTR_WO(unassign_adapter);
@@ -987,7 +1034,7 @@ static ssize_t assign_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
- mutex_lock(&matrix_dev->mdevs_lock);
+ get_update_locks_for_mdev(matrix_mdev);
/* If the KVM guest is running, disallow assignment of domain */
if (matrix_mdev->kvm) {
@@ -1018,7 +1065,7 @@ static ssize_t assign_domain_store(struct device *dev,
matrix_mdev);
ret = count;
done:
- mutex_unlock(&matrix_dev->mdevs_lock);
+ release_update_locks_for_mdev(matrix_mdev);
return ret;
}
@@ -1061,7 +1108,7 @@ static ssize_t unassign_domain_store(struct device *dev,
unsigned long apqi;
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->mdevs_lock);
+ get_update_locks_for_mdev(matrix_mdev);
/* If the KVM guest is running, disallow unassignment of domain */
if (matrix_mdev->kvm) {
@@ -1087,7 +1134,7 @@ static ssize_t unassign_domain_store(struct device *dev,
ret = count;
done:
- mutex_unlock(&matrix_dev->mdevs_lock);
+ release_update_locks_for_mdev(matrix_mdev);
return ret;
}
static DEVICE_ATTR_WO(unassign_domain);
@@ -1114,7 +1161,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
unsigned long id;
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
- mutex_lock(&matrix_dev->mdevs_lock);
+ get_update_locks_for_mdev(matrix_mdev);
/* If the KVM guest is running, disallow assignment of control domain */
if (matrix_mdev->kvm) {
@@ -1140,7 +1187,7 @@ static ssize_t assign_control_domain_store(struct device *dev,
vfio_ap_mdev_filter_cdoms(matrix_mdev);
ret = count;
done:
- mutex_unlock(&matrix_dev->mdevs_lock);
+ release_update_locks_for_mdev(matrix_mdev);
return ret;
}
static DEVICE_ATTR_WO(assign_control_domain);
@@ -1168,7 +1215,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
unsigned long max_domid = matrix_mdev->matrix.adm_max;
- mutex_lock(&matrix_dev->mdevs_lock);
+ get_update_locks_for_mdev(matrix_mdev);
/* If a KVM guest is running, disallow unassignment of control domain */
if (matrix_mdev->kvm) {
@@ -1191,7 +1238,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,
ret = count;
done:
- mutex_unlock(&matrix_dev->mdevs_lock);
+ release_update_locks_for_mdev(matrix_mdev);
return ret;
}
static DEVICE_ATTR_WO(unassign_control_domain);