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From:   Alexandre Chartre <alexandre.chartre@oracle.com>
To:     tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com,
        dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org,
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Cc:     pbonzini@redhat.com, konrad.wilk@oracle.com,
        jan.setjeeilers@oracle.com, liran.alon@oracle.com,
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        kuzuno@gmail.com, mgross@linux.intel.com,
        alexandre.chartre@oracle.com
Subject: [RFC v4][PATCH part-3 05/14] asidrv: Sequence to test interrupt on ASI
Date:   Mon,  4 May 2020 17:02:26 +0200
Message-Id: <20200504150235.12171-6-alexandre.chartre@oracle.com>
In-Reply-To: <20200504150235.12171-1-alexandre.chartre@oracle.com>
References: <20200504150235.12171-1-alexandre.chartre@oracle.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Add a sequence to test if an ASI remains active after receiving
an interrupt.

Signed-off-by: Alexandre Chartre <alexandre.chartre@oracle.com>
---
 drivers/staging/asi/asidrv.c | 144 +++++++++++++++++++++++++++++++++--
 drivers/staging/asi/asidrv.h |   5 ++
 2 files changed, 144 insertions(+), 5 deletions(-)

diff --git a/drivers/staging/asi/asidrv.c b/drivers/staging/asi/asidrv.c
index 4231b56db167..a3c7da2bf16e 100644
--- a/drivers/staging/asi/asidrv.c
+++ b/drivers/staging/asi/asidrv.c
@@ -7,6 +7,7 @@
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 
 #include <asm/asi.h>
 #include <asm/dpt.h>
@@ -19,6 +20,12 @@
 /* Number of read for mem/memmap test sequence */
 #define ASIDRV_MEM_READ_COUNT		1000
 
+/* Timeout for target to be ready to receive an interrupt */
+#define ASIDRV_TIMEOUT_TARGET_READY	1
+
+/* Timeout for receiving an interrupt */
+#define ASIDRV_TIMEOUT_INTERRUPT	5
+
 enum asidrv_state {
 	ASIDRV_STATE_NONE,
 	ASIDRV_STATE_INTR_WAITING,
@@ -29,6 +36,13 @@ struct asidrv_test {
 	struct asi		*asi;	/* ASI for testing */
 	struct dpt		*dpt;	/* ASI decorated page-table */
 	char			*buffer; /* buffer for testing */
+
+	/* runtime */
+	atomic_t		state;	/* runtime state */
+	int			cpu;	/* cpu the test is running on */
+	struct work_struct	work;	/* work for other cpu */
+	bool			work_set;
+	enum asidrv_run_error	run_error;
 };
 
 struct asidrv_sequence {
@@ -160,6 +174,107 @@ static int asidrv_asi_is_active(struct asi *asi)
 	return false;
 }
 
+/*
+ * Wait for an atomic value to be set or the timeout to expire.
+ * Return 0 if the value is set, or -1 if the timeout expires.
+ */
+static enum asidrv_run_error asidrv_wait(struct asidrv_test *test,
+					 int value, unsigned int timeout)
+{
+	cycles_t start = get_cycles();
+	cycles_t stop = start + timeout * tsc_khz * 1000;
+
+	while (get_cycles() < stop) {
+		if (atomic_read(&test->state) == value ||
+		    test->run_error != ASIDRV_RUN_ERR_NONE)
+			return test->run_error;
+		cpu_relax();
+	}
+
+	/* timeout reached */
+	return ASIDRV_RUN_ERR_TIMEOUT;
+}
+
+/*
+ * Wait for an atomic value to transition from the initial value (set
+ * on entry) to the final value, or to timeout. Return 0 if the transition
+ * was done, or -1 if the timeout expires.
+ */
+static enum asidrv_run_error asidrv_wait_transition(struct asidrv_test *test,
+						    int initial, int final,
+						    unsigned int timeout)
+{
+	/* set the initial state value */
+	atomic_set(&test->state, initial);
+
+	/* do an active wait for the state changes */
+	return asidrv_wait(test, final, timeout);
+}
+
+/*
+ * Interrupt Test Sequence
+ */
+
+static void asidrv_intr_handler(void *info)
+{
+	struct asidrv_test *test = info;
+
+	/* ASI should be interrupted by the interrupt */
+	if (asidrv_asi_is_active(test->asi)) {
+		test->run_error = ASIDRV_RUN_ERR_INTR_ASI_ACTIVE;
+		atomic_set(&test->state, ASIDRV_STATE_INTR_RECEIVED);
+		return;
+	}
+
+	pr_debug("Received interrupt\n");
+	atomic_set(&test->state, ASIDRV_STATE_INTR_RECEIVED);
+}
+
+static void asidrv_intr_send(struct work_struct *work)
+{
+	struct asidrv_test *test = container_of(work, struct asidrv_test, work);
+	enum asidrv_run_error err;
+
+	/* wait for cpu target to be ready, then send an interrupt */
+	err = asidrv_wait(test,
+			  ASIDRV_STATE_INTR_WAITING,
+			  ASIDRV_TIMEOUT_TARGET_READY);
+	if (err) {
+		pr_debug("Target cpu %d not ready, interrupt not sent: error %d\n",
+			 test->cpu, err);
+		return;
+	}
+
+	pr_debug("Sending interrupt to cpu %d\n", test->cpu);
+	smp_call_function_single(test->cpu, asidrv_intr_handler,
+				 test, false);
+}
+
+static enum asidrv_run_error asidrv_intr_setup(struct asidrv_test *test)
+{
+	/* set work to have another cpu to send us an interrupt */
+	INIT_WORK(&test->work, asidrv_intr_send);
+	test->work_set = true;
+	return ASIDRV_RUN_ERR_NONE;
+}
+
+static enum asidrv_run_error asidrv_intr_run(struct asidrv_test *test)
+{
+	enum asidrv_run_error err;
+
+	/* wait for state changes indicating that an interrupt was received */
+	err = asidrv_wait_transition(test,
+				     ASIDRV_STATE_INTR_WAITING,
+				     ASIDRV_STATE_INTR_RECEIVED,
+				     ASIDRV_TIMEOUT_INTERRUPT);
+	if (err == ASIDRV_RUN_ERR_TIMEOUT) {
+		pr_debug("Interrupt wait timeout\n");
+		err = ASIDRV_RUN_ERR_INTR;
+	}
+
+	return err;
+}
+
 /*
  * Memory Buffer Access Test Sequences
  */
@@ -231,12 +346,18 @@ struct asidrv_sequence asidrv_sequences[] = {
 		"memmap",
 		asidrv_memmap_setup, asidrv_mem_run, asidrv_memmap_cleanup,
 	},
+	[ASIDRV_SEQ_INTERRUPT] = {
+		"interrupt",
+		asidrv_intr_setup, asidrv_intr_run, NULL,
+	},
 };
 
 static enum asidrv_run_error asidrv_run_init(struct asidrv_test *test)
 {
 	int err;
 
+	test->run_error = ASIDRV_RUN_ERR_NONE;
+
 	/*
 	 * Map the current stack, we need it to enter ASI.
 	 */
@@ -272,18 +393,31 @@ static void asidrv_run_fini(struct asidrv_test *test)
 static enum asidrv_run_error asidrv_run_setup(struct asidrv_test *test,
 					      struct asidrv_sequence *sequence)
 {
-	int run_err = ASIDRV_RUN_ERR_NONE;
+	unsigned int other_cpu;
+	int run_err;
+
+	test->work_set = false;
 
 	if (sequence->setup) {
 		run_err = sequence->setup(test);
 		if (run_err)
-			goto failed;
+			return run_err;
 	}
 
-	return ASIDRV_RUN_ERR_NONE;
+	if (test->work_set) {
+		other_cpu = cpumask_any_but(cpu_online_mask, test->cpu);
+		if (other_cpu == test->cpu) {
+			pr_debug("Sequence %s requires an extra online cpu\n",
+				 sequence->name);
+			asidrv_run_cleanup(test, sequence);
+			return ASIDRV_RUN_ERR_NCPUS;
+		}
 
-failed:
-	return run_err;
+		atomic_set(&test->state, ASIDRV_STATE_NONE);
+		schedule_work_on(other_cpu, &test->work);
+	}
+
+	return ASIDRV_RUN_ERR_NONE;
 }
 
 static void asidrv_run_cleanup(struct asidrv_test *test,
diff --git a/drivers/staging/asi/asidrv.h b/drivers/staging/asi/asidrv.h
index 1e820cc64f13..8055d96a0058 100644
--- a/drivers/staging/asi/asidrv.h
+++ b/drivers/staging/asi/asidrv.h
@@ -10,6 +10,7 @@ enum asidrv_seqnum {
 	ASIDRV_SEQ_PRINTK,	/* printk sequence */
 	ASIDRV_SEQ_MEM,		/* access unmapped memory */
 	ASIDRV_SEQ_MEMMAP,	/* access mapped memory */
+	ASIDRV_SEQ_INTERRUPT,	/* interrupt sequence */
 };
 
 enum asidrv_run_error {
@@ -20,6 +21,10 @@ enum asidrv_run_error {
 	ASIDRV_RUN_ERR_ENTER,	/* failed to enter ASI */
 	ASIDRV_RUN_ERR_ACTIVE,	/* ASI is not active after entering ASI */
 	ASIDRV_RUN_ERR_MAP_BUFFER, /* failed to map buffer */
+	ASIDRV_RUN_ERR_NCPUS,	/* not enough active cpus */
+	ASIDRV_RUN_ERR_INTR,	/* no interrupt received */
+	ASIDRV_RUN_ERR_INTR_ASI_ACTIVE, /* ASI active in interrupt handler */
+	ASIDRV_RUN_ERR_TIMEOUT,
 };
 
 #define ASIDRV_IOCTL_RUN_SEQUENCE	_IOWR('a', 1, struct asidrv_run_param)
-- 
2.18.2