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Subject[PATCH 4.19 087/321] s390/zcrypt: make sysfs reset attribute trigger queue reset
Date
From: Harald Freudenberger <freude@linux.ibm.com>

[ Upstream commit 42a87d4103ae365e18c3be1333592ab583b8ad9d ]

Until now there is no way to reset a AP queue or card. Driving a card
or queue offline and online again does only toggle the 'software'
online state. The only way to trigger a (hardware) reset is by running
hot-unplug/hot-plug for example on the HMC.

This patch makes the queue reset attribute in sysfs writable.
Writing into this attribute triggers a reset on the AP queue's state
machine. So the AP queue is flushed and state machine runs through the
initial states which cause a reset (PQAP(RAPQ)) and a re-registration
to interrupts (PQAP(AQIC)) if available.

The reset sysfs attribute is writable by root only. So only an
administrator is allowed to initiate a reset of AP queues. Please note
that the queue's counter values are left untouched by the reset.

Signed-off-by: Harald Freudenberger <freude@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/s390/crypto/ap_queue.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/s390/crypto/ap_queue.c b/drivers/s390/crypto/ap_queue.c
index 0aa4b3ccc948c..576ac08777c50 100644
--- a/drivers/s390/crypto/ap_queue.c
+++ b/drivers/s390/crypto/ap_queue.c
@@ -14,6 +14,9 @@
#include <asm/facility.h>

#include "ap_bus.h"
+#include "ap_debug.h"
+
+static void __ap_flush_queue(struct ap_queue *aq);

/**
* ap_queue_enable_interruption(): Enable interruption on an AP queue.
@@ -541,7 +544,25 @@ static ssize_t reset_show(struct device *dev,
return rc;
}

-static DEVICE_ATTR_RO(reset);
+static ssize_t reset_store(struct device *dev,
+ struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct ap_queue *aq = to_ap_queue(dev);
+
+ spin_lock_bh(&aq->lock);
+ __ap_flush_queue(aq);
+ aq->state = AP_STATE_RESET_START;
+ ap_wait(ap_sm_event(aq, AP_EVENT_POLL));
+ spin_unlock_bh(&aq->lock);
+
+ AP_DBF(DBF_INFO, "reset queue=%02x.%04x triggered by user\n",
+ AP_QID_CARD(aq->qid), AP_QID_QUEUE(aq->qid));
+
+ return count;
+}
+
+static DEVICE_ATTR_RW(reset);

static ssize_t interrupt_show(struct device *dev,
struct device_attribute *attr, char *buf)
--
2.20.1


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