From: Harald Freudenberger freude@linux.ibm.com
commit 0fef40be5d1f8e7af3d61e8827a63c5862cd99f7 upstream.
On older z series machines (z12 and older) there is no QCI info available. The AP code took care of this and the AP bus scan then switched to simple probing via TAPQ.
With commit 283915850a44 ("s390/ap: notify drivers on config changed and scan complete callbacks") some code was introduced which silently assumed that the QCI info is always available. However, with KVM simulating an older machine (z12) the result was a kernel crash. Funnily the same crash does not happen on LPAR - maybe because NULL is a valid pointer and reading some data from address 0 also works fine.
This fix now improves the code to be aware that the QCI instruction may not be available on older machines and thus the two pointers to QCI info structs may simple be NULL.
However, on a machine not providing the QCI info the two callbacks to the zcrypt device drivers on_config_changed() and on_scan_complete() provide parameters which are pointers to a QCI info struct. These both callbacks are NOT served if there is no QCI info available. The only consumer of these callbacks is the vfio device driver. This driver only supports CEX4 and higher. All physical machines which are able to provide CEX4 cards have QCI support available. So there is no sense in for example fill the QCI info struct by hand with looping over cards and queues and TAPQ each APQN.
Signed-off-by: Harald Freudenberger freude@linux.ibm.com Signed-off-by: Tony Krowiak akrowiak@linux.ibm.com Cc: stable@vger.kernel.org Fixes: 283915850a44 ("s390/ap: notify drivers on config changed and scan complete callbacks") Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/s390/crypto/ap_bus.c | 3 +++ drivers/s390/crypto/ap_bus.h | 4 ++++ 2 files changed, 7 insertions(+)
--- a/drivers/s390/crypto/ap_bus.c +++ b/drivers/s390/crypto/ap_bus.c @@ -2068,6 +2068,9 @@ static inline void ap_scan_adapter(int a */ static bool ap_get_configuration(void) { + if (!ap_qci_info) /* QCI not supported */ + return false; + memcpy(ap_qci_info_old, ap_qci_info, sizeof(*ap_qci_info)); ap_fetch_qci_info(ap_qci_info);
--- a/drivers/s390/crypto/ap_bus.h +++ b/drivers/s390/crypto/ap_bus.h @@ -148,12 +148,16 @@ struct ap_driver { /* * Called at the start of the ap bus scan function when * the crypto config information (qci) has changed. + * This callback is not invoked if there is no AP + * QCI support available. */ void (*on_config_changed)(struct ap_config_info *new_config_info, struct ap_config_info *old_config_info); /* * Called at the end of the ap bus scan function when * the crypto config information (qci) has changed. + * This callback is not invoked if there is no AP + * QCI support available. */ void (*on_scan_complete)(struct ap_config_info *new_config_info, struct ap_config_info *old_config_info);