[PATCH 4/7] s390: vfio-ap: allow hot plug/unplug of AP resources using mdev device

Tony Krowiak
2019-04-11T21:03:21Z

Let's allow adapters, domains and control domains to be assigned to or
unassigned from an AP matrix mdev device while it is in use by a guest.
When an adapter, domain or control domain is assigned to or unassigned
from an mdev device while a guest is using it, the guest's CRYCB will be
updated thus giving access to the resource assigned, or taking access away
from the resource unassigned for the guest.

Signed-off-by: Tony Krowiak <akrowiak@linux.ibm.com>
---
drivers/s390/crypto/vfio_ap_ops.c | 68 +++++++++++++++++++--------------------
1 file changed, 33 insertions(+), 35 deletions(-)

diff --git a/drivers/s390/crypto/vfio_ap_ops.c b/drivers/s390/crypto/vfio_ap_ops.c
index cb3e4f7671be..cda1d216ee38 100644
--- a/drivers/s390/crypto/vfio_ap_ops.c
+++ b/drivers/s390/crypto/vfio_ap_ops.c
@@ -155,6 +155,24 @@ static int vfio_ap_mdev_verify_no_sharing(struct ap_matrix_mdev *matrix_mdev)
return 0;
}

+/*
+ * vfio_ap_mdev_update_crycb
+ *
+ * @matrix_mdev: the mediated matrix device
+ *
+ * Updates the AP matrix in the guest's CRYCB from the masks configured for the
+ * mediated matrix device via its sysfs interfaces.
+ */
+static void vfio_ap_mdev_update_crycb(struct ap_matrix_mdev *matrix_mdev)
+{
+ if (matrix_mdev->kvm) {
+ kvm_arch_crypto_set_masks(matrix_mdev->kvm,
+ matrix_mdev->matrix.apm,
+ matrix_mdev->matrix.aqm,
+ matrix_mdev->matrix.adm);
+ }
+}
+
/**
* assign_adapter_store
*
@@ -196,10 +214,6 @@ static ssize_t assign_adapter_store(struct device *dev,
struct mdev_device *mdev = mdev_from_dev(dev);
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

- /* If the guest is running, disallow assignment of adapter */
- if (matrix_mdev->kvm)
- return -EBUSY;
-
ret = kstrtoul(buf, 0, &apid);
if (ret)
return ret;
@@ -214,16 +228,12 @@ static ssize_t assign_adapter_store(struct device *dev,
*/
mutex_lock(&matrix_dev->lock);

- ret = vfio_ap_mdev_verify_queues_reserved_for_apid(matrix_mdev, apid);
- if (ret)
- goto done;
-
set_bit_inv(apid, matrix_mdev->matrix.apm);

ret = ap_apqn_in_matrix_owned_by_def_drv(matrix_mdev->matrix.apm,
matrix_mdev->matrix.aqm);

- /* If any APQN is reserved for used by the default drivers */
+ /* If any APQN is owned by the default drivers */
ret = (ret == 1) ? -EADDRNOTAVAIL : ret;
if (ret)
goto error;
@@ -232,6 +242,7 @@ static ssize_t assign_adapter_store(struct device *dev,
if (ret)
goto error;

+ vfio_ap_mdev_update_crycb(matrix_mdev);
ret = count;
goto done;

@@ -270,10 +281,6 @@ static ssize_t unassign_adapter_store(struct device *dev,
struct mdev_device *mdev = mdev_from_dev(dev);
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

- /* If the guest is running, disallow un-assignment of adapter */
- if (matrix_mdev->kvm)
- return -EBUSY;
-
ret = kstrtoul(buf, 0, &apid);
if (ret)
return ret;
@@ -283,6 +290,7 @@ static ssize_t unassign_adapter_store(struct device *dev,

mutex_lock(&matrix_dev->lock);
clear_bit_inv((unsigned long)apid, matrix_mdev->matrix.apm);
+ vfio_ap_mdev_update_crycb(matrix_mdev);
mutex_unlock(&matrix_dev->lock);

return count;
@@ -331,10 +339,6 @@ static ssize_t assign_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
unsigned long max_apqi = matrix_mdev->matrix.aqm_max;

- /* If the guest is running, disallow assignment of domain */
- if (matrix_mdev->kvm)
- return -EBUSY;
-
ret = kstrtoul(buf, 0, &apqi);
if (ret)
return ret;
@@ -355,12 +359,13 @@ static ssize_t assign_domain_store(struct device *dev,

ret = vfio_ap_mdev_verify_no_sharing(matrix_mdev);
if (ret)
- goto share_err;
+ goto error;

+ vfio_ap_mdev_update_crycb(matrix_mdev);
ret = count;
goto done;

-share_err:
+error:
clear_bit_inv(apqi, matrix_mdev->matrix.aqm);
done:
mutex_unlock(&matrix_dev->lock);
@@ -396,10 +401,6 @@ static ssize_t unassign_domain_store(struct device *dev,
struct mdev_device *mdev = mdev_from_dev(dev);
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

- /* If the guest is running, disallow un-assignment of domain */
- if (matrix_mdev->kvm)
- return -EBUSY;
-
ret = kstrtoul(buf, 0, &apqi);
if (ret)
return ret;
@@ -409,6 +410,7 @@ static ssize_t unassign_domain_store(struct device *dev,

mutex_lock(&matrix_dev->lock);
clear_bit_inv((unsigned long)apqi, matrix_mdev->matrix.aqm);
+ vfio_ap_mdev_update_crycb(matrix_mdev);
mutex_unlock(&matrix_dev->lock);

return count;
@@ -440,10 +442,6 @@ static ssize_t assign_control_domain_store(struct device *dev,
struct mdev_device *mdev = mdev_from_dev(dev);
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);

- /* If the guest is running, disallow assignment of control domain */
- if (matrix_mdev->kvm)
- return -EBUSY;
-
ret = kstrtoul(buf, 0, &id);
if (ret)
return ret;
@@ -451,13 +449,16 @@ static ssize_t assign_control_domain_store(struct device *dev,
if (id > matrix_mdev->matrix.adm_max)
return -ENODEV;

- /* Set the bit in the ADM (bitmask) corresponding to the AP control
- * domain number (id). The bits in the mask, from most significant to
- * least significant, correspond to IDs 0 up to the one less than the
- * number of control domains that can be assigned.
+ /*
+ * Set the bits in the ADM (bitmask) corresponding to the AP control
+ * domain numbers in dommask. The bits in the mask, from left to right,
+ * correspond to IDs 0 up to the one less than the number of control
+ * domains that can be assigned.
+ *
*/
mutex_lock(&matrix_dev->lock);
set_bit_inv(id, matrix_mdev->matrix.adm);
+ vfio_ap_mdev_update_crycb(matrix_mdev);
mutex_unlock(&matrix_dev->lock);

return count;
@@ -490,10 +491,6 @@ static ssize_t unassign_control_domain_store(struct device *dev,
struct ap_matrix_mdev *matrix_mdev = mdev_get_drvdata(mdev);
unsigned long max_domid = matrix_mdev->matrix.adm_max;

- /* If the guest is running, disallow un-assignment of control domain */
- if (matrix_mdev->kvm)
- return -EBUSY;
-
ret = kstrtoul(buf, 0, &domid);
if (ret)
return ret;
@@ -502,6 +499,7 @@ static ssize_t unassign_control_domain_store(struct device *dev,

mutex_lock(&matrix_dev->lock);
clear_bit_inv(domid, matrix_mdev->matrix.adm);
+ vfio_ap_mdev_update_crycb(matrix_mdev);
mutex_unlock(&matrix_dev->lock);

return count;
--
2.7.4