[PATCH v20 12/20] s390/vfio-ap: allow hot plug/unplug of AP devices when assigned/unassigned

[Tony Krowiak]

Let's hot plug an adapter, domain or control domain into the guest when it
is assigned to a matrix mdev that is attached to a KVM guest. Likewise,
let's hot unplug an adapter, domain or control domain from the guest when
it is unassigned from a matrix_mdev that is attached to a KVM guest.

Whenever an assignment or unassignment of an adapter, domain or control
domain is performed, the APQNs and control domains assigned to the matrix
mdev will be filtered and assigned to the AP control block
(APCB) that supplies the AP configuration to the guest so that no
adapter, domain or control domain that is not in the host's AP
configuration nor any APQN that does not reference a queue device bound
to the vfio_ap device driver is assigned.

After updating the APCB, if the mdev is in use by a KVM guest, it is
hot plugged into the guest to dynamically provide access to the adapters,
domains and control domains provided via the newly refreshed APCB.

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
Reviewed-by: Jason J. Herne <jjherne@xxxxxxxxxxxxx>
---
 drivers/s390/crypto/vfio_ap_ops.c | 112 +++++++++++++++---------------
 1 file changed, 57 insertions(+), 55 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index 6d55713c7f7a..93e932458590 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -600,10 +600,25 @@ static void vfio_ap_matrix_init(struct ap_config_info *info,
 	matrix->adm_max = info->apxa ? info->Nd : 15;
 }
 
-static void vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)
+static void vfio_ap_mdev_update_guest_apcb(struct ap_matrix_mdev *matrix_mdev)
 {
+	if (matrix_mdev->kvm)
+		kvm_arch_crypto_set_masks(matrix_mdev->kvm,
+					  matrix_mdev->shadow_apcb.apm,
+					  matrix_mdev->shadow_apcb.aqm,
+					  matrix_mdev->shadow_apcb.adm);
+}
+
+static bool vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)
+{
+	DECLARE_BITMAP(prev_shadow_adm, AP_DOMAINS);
+
+	bitmap_copy(prev_shadow_adm, matrix_mdev->shadow_apcb.adm, AP_DOMAINS);
 	bitmap_and(matrix_mdev->shadow_apcb.adm, matrix_mdev->matrix.adm,
 		   (unsigned long *)matrix_dev->info.adm, AP_DOMAINS);
+
+	return !bitmap_equal(prev_shadow_adm, matrix_mdev->shadow_apcb.adm,
+			     AP_DOMAINS);
 }
 
 /*
@@ -618,17 +633,24 @@ static void vfio_ap_mdev_filter_cdoms(struct ap_matrix_mdev *matrix_mdev)
  *	 driver, its APID will be filtered from the guest's APCB. The matrix
  *	 structure precludes filtering an individual APQN, so its APID will be
  *	 filtered.
+ *
+ * Return: a boolean value indicating whether the KVM guest's APCB was changed
+ *	   by the filtering or not.
  */
-static void vfio_ap_mdev_filter_matrix(unsigned long *apm, unsigned long *aqm,
+static bool vfio_ap_mdev_filter_matrix(unsigned long *apm, unsigned long *aqm,
 				       struct ap_matrix_mdev *matrix_mdev)
 {
 	int ret;
 	unsigned long apid, apqi, apqn;
+	DECLARE_BITMAP(prev_shadow_apm, AP_DEVICES);
+	DECLARE_BITMAP(prev_shadow_aqm, AP_DOMAINS);
 
 	ret = ap_qci(&matrix_dev->info);
 	if (ret)
-		return;
+		return false;
 
+	bitmap_copy(prev_shadow_apm, matrix_mdev->shadow_apcb.apm, AP_DEVICES);
+	bitmap_copy(prev_shadow_aqm, matrix_mdev->shadow_apcb.aqm, AP_DOMAINS);
 	vfio_ap_matrix_init(&matrix_dev->info, &matrix_mdev->shadow_apcb);
 
 	/*
@@ -660,6 +682,11 @@ static void vfio_ap_mdev_filter_matrix(unsigned long *apm, unsigned long *aqm,
 			}
 		}
 	}
+
+	return !bitmap_equal(prev_shadow_apm, matrix_mdev->shadow_apcb.apm,
+			     AP_DEVICES) ||
+	       !bitmap_equal(prev_shadow_aqm, matrix_mdev->shadow_apcb.aqm,
+			     AP_DOMAINS);
 }
 
 static int vfio_ap_mdev_probe(struct mdev_device *mdev)
@@ -935,17 +962,10 @@ static ssize_t assign_adapter_store(struct device *dev,
 	int ret;
 	unsigned long apid;
 	DECLARE_BITMAP(apm_delta, AP_DEVICES);
-
 	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
 
 	get_update_locks_for_mdev(matrix_mdev);
 
-	/* If the KVM guest is running, disallow assignment of adapter */
-	if (matrix_mdev->kvm) {
-		ret = -EBUSY;
-		goto done;
-	}
-
 	ret = kstrtoul(buf, 0, &apid);
 	if (ret)
 		goto done;
@@ -966,8 +986,11 @@ static ssize_t assign_adapter_store(struct device *dev,
 	vfio_ap_mdev_link_adapter(matrix_mdev, apid);
 	memset(apm_delta, 0, sizeof(apm_delta));
 	set_bit_inv(apid, apm_delta);
-	vfio_ap_mdev_filter_matrix(apm_delta,
-				   matrix_mdev->matrix.aqm, matrix_mdev);
+
+	if (vfio_ap_mdev_filter_matrix(apm_delta,
+				       matrix_mdev->matrix.aqm, matrix_mdev))
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+
 	ret = count;
 done:
 	release_update_locks_for_mdev(matrix_mdev);
@@ -1015,12 +1038,6 @@ static ssize_t unassign_adapter_store(struct device *dev,
 
 	get_update_locks_for_mdev(matrix_mdev);
 
-	/* If the KVM guest is running, disallow unassignment of adapter */
-	if (matrix_mdev->kvm) {
-		ret = -EBUSY;
-		goto done;
-	}
-
 	ret = kstrtoul(buf, 0, &apid);
 	if (ret)
 		goto done;
@@ -1033,8 +1050,10 @@ static ssize_t unassign_adapter_store(struct device *dev,
 	clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
 	vfio_ap_mdev_unlink_adapter(matrix_mdev, apid);
 
-	if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm))
+	if (test_bit_inv(apid, matrix_mdev->shadow_apcb.apm)) {
 		clear_bit_inv(apid, matrix_mdev->shadow_apcb.apm);
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+	}
 
 	ret = count;
 done:
@@ -1091,20 +1110,14 @@ static ssize_t assign_domain_store(struct device *dev,
 	unsigned long apqi;
 	DECLARE_BITMAP(aqm_delta, AP_DOMAINS);
 	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
-	unsigned long max_apqi = matrix_mdev->matrix.aqm_max;
 
 	get_update_locks_for_mdev(matrix_mdev);
 
-	/* If the KVM guest is running, disallow assignment of domain */
-	if (matrix_mdev->kvm) {
-		ret = -EBUSY;
-		goto done;
-	}
-
 	ret = kstrtoul(buf, 0, &apqi);
 	if (ret)
 		goto done;
-	if (apqi > max_apqi) {
+
+	if (apqi > matrix_mdev->matrix.aqm_max) {
 		ret = -ENODEV;
 		goto done;
 	}
@@ -1120,8 +1133,11 @@ static ssize_t assign_domain_store(struct device *dev,
 	vfio_ap_mdev_link_domain(matrix_mdev, apqi);
 	memset(aqm_delta, 0, sizeof(aqm_delta));
 	set_bit_inv(apqi, aqm_delta);
-	vfio_ap_mdev_filter_matrix(matrix_mdev->matrix.apm, aqm_delta,
-				   matrix_mdev);
+
+	if (vfio_ap_mdev_filter_matrix(matrix_mdev->matrix.apm, aqm_delta,
+				       matrix_mdev))
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+
 	ret = count;
 done:
 	release_update_locks_for_mdev(matrix_mdev);
@@ -1169,12 +1185,6 @@ static ssize_t unassign_domain_store(struct device *dev,
 
 	get_update_locks_for_mdev(matrix_mdev);
 
-	/* If the KVM guest is running, disallow unassignment of domain */
-	if (matrix_mdev->kvm) {
-		ret = -EBUSY;
-		goto done;
-	}
-
 	ret = kstrtoul(buf, 0, &apqi);
 	if (ret)
 		goto done;
@@ -1187,8 +1197,10 @@ static ssize_t unassign_domain_store(struct device *dev,
 	clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
 	vfio_ap_mdev_unlink_domain(matrix_mdev, apqi);
 
-	if (test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm))
+	if (test_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm)) {
 		clear_bit_inv(apqi, matrix_mdev->shadow_apcb.aqm);
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+	}
 
 	ret = count;
 
@@ -1222,12 +1234,6 @@ static ssize_t assign_control_domain_store(struct device *dev,
 
 	get_update_locks_for_mdev(matrix_mdev);
 
-	/* If the KVM guest is running, disallow assignment of control domain */
-	if (matrix_mdev->kvm) {
-		ret = -EBUSY;
-		goto done;
-	}
-
 	ret = kstrtoul(buf, 0, &id);
 	if (ret)
 		goto done;
@@ -1243,7 +1249,9 @@ static ssize_t assign_control_domain_store(struct device *dev,
 	 * number of control domains that can be assigned.
 	 */
 	set_bit_inv(id, matrix_mdev->matrix.adm);
-	vfio_ap_mdev_filter_cdoms(matrix_mdev);
+	if (vfio_ap_mdev_filter_cdoms(matrix_mdev))
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+
 	ret = count;
 done:
 	release_update_locks_for_mdev(matrix_mdev);
@@ -1272,28 +1280,24 @@ static ssize_t unassign_control_domain_store(struct device *dev,
 	int ret;
 	unsigned long domid;
 	struct ap_matrix_mdev *matrix_mdev = dev_get_drvdata(dev);
-	unsigned long max_domid =  matrix_mdev->matrix.adm_max;
 
 	get_update_locks_for_mdev(matrix_mdev);
 
-	/* If a KVM guest is running, disallow unassignment of control domain */
-	if (matrix_mdev->kvm) {
-		ret = -EBUSY;
-		goto done;
-	}
-
 	ret = kstrtoul(buf, 0, &domid);
 	if (ret)
 		goto done;
-	if (domid > max_domid) {
+
+	if (domid > matrix_mdev->matrix.adm_max) {
 		ret = -ENODEV;
 		goto done;
 	}
 
 	clear_bit_inv(domid, matrix_mdev->matrix.adm);
 
-	if (test_bit_inv(domid, matrix_mdev->shadow_apcb.adm))
+	if (test_bit_inv(domid, matrix_mdev->shadow_apcb.adm)) {
 		clear_bit_inv(domid, matrix_mdev->shadow_apcb.adm);
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
+	}
 
 	ret = count;
 done:
@@ -1426,9 +1430,7 @@ static int vfio_ap_mdev_set_kvm(struct ap_matrix_mdev *matrix_mdev,
 
 		kvm_get_kvm(kvm);
 		matrix_mdev->kvm = kvm;
-		kvm_arch_crypto_set_masks(kvm, matrix_mdev->shadow_apcb.apm,
-					  matrix_mdev->shadow_apcb.aqm,
-					  matrix_mdev->shadow_apcb.adm);
+		vfio_ap_mdev_update_guest_apcb(matrix_mdev);
 
 		release_update_locks_for_kvm(kvm);
 	}
-- 
2.35.3