[kvm-unit-tests PATCH v1 3/6] s390x: lib: css: upgrading IRQ handling

[Pierre Morel <pmorel@linux.ibm.com>]

Until now we had very few usage of interrupts, to be able to handle
several interrupts coming up asynchronously we need to take care
to save the previous interrupt before handling the next one.

Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
---
 lib/s390x/css.h     |  29 +++++++++++
 lib/s390x/css_lib.c | 117 ++++++++++++++++++++++++++++++++++----------
 2 files changed, 120 insertions(+), 26 deletions(-)

diff --git a/lib/s390x/css.h b/lib/s390x/css.h
index 460b0bd..65fc335 100644
--- a/lib/s390x/css.h
+++ b/lib/s390x/css.h
@@ -425,4 +425,33 @@ struct measurement_block_format1 {
 	uint32_t irq_prio_delay_time;
 };
 
+struct irq_entry {
+	struct irq_entry *next;
+	struct irb irb;
+	uint32_t sid;
+};
+
+struct irq_entry *alloc_irq(void);
+struct irq_entry *get_irq(void);
+void put_irq(struct irq_entry *irq);
+
+#include <asm/arch_def.h>
+static inline void disable_io_irq(void)
+{
+	uint64_t mask;
+
+	mask = extract_psw_mask();
+	mask &= ~PSW_MASK_IO;
+	load_psw_mask(mask);
+}
+
+static inline void enable_io_irq(void)
+{
+	uint64_t mask;
+
+	mask = extract_psw_mask();
+	mask |= PSW_MASK_IO;
+	load_psw_mask(mask);
+}
+
 #endif
diff --git a/lib/s390x/css_lib.c b/lib/s390x/css_lib.c
index f8db205..211c73c 100644
--- a/lib/s390x/css_lib.c
+++ b/lib/s390x/css_lib.c
@@ -9,6 +9,8 @@
  */
 #include <libcflat.h>
 #include <alloc_phys.h>
+#include <util.h>
+#include <alloc.h>
 #include <asm/page.h>
 #include <string.h>
 #include <interrupt.h>
@@ -22,6 +24,46 @@
 struct schib schib;
 struct chsc_scsc *chsc_scsc;
 
+static struct irq_entry *irqs;
+
+struct irq_entry *get_irq(void)
+{
+	struct irq_entry *irq = NULL;
+
+	if (irqs) {
+		irq = irqs;
+		irqs = irq->next;
+	}
+	return irq;
+}
+
+void put_irq(struct irq_entry *irq)
+{
+	free(irq);
+}
+
+static void save_irq(struct irq_entry *irq)
+{
+	struct irq_entry *e;
+
+	if (!irqs) {
+		irqs = irq;
+	} else {
+		e = irqs;
+		while (e && e->next)
+			e = e->next;
+		e->next = irq;
+	}
+}
+
+struct irq_entry *alloc_irq(void)
+{
+	struct irq_entry *irq;
+
+	irq = calloc(1, sizeof(*irq));
+	return irq;
+}
+
 static const char * const chsc_rsp_description[] = {
 	"CHSC unknown error",
 	"Command executed",
@@ -422,38 +464,38 @@ static struct irb irb;
 void css_irq_io(void)
 {
 	int ret = 0;
-	char *flags;
-	int sid;
+	struct irq_entry *irq;
 
 	report_prefix_push("Interrupt");
-	sid = lowcore_ptr->subsys_id_word;
+	irq = alloc_irq();
+	assert(irq);
+
+	irq->sid = lowcore_ptr->subsys_id_word;
 	/* Lowlevel set the SID as interrupt parameter. */
-	if (lowcore_ptr->io_int_param != sid) {
+	if (lowcore_ptr->io_int_param != irq->sid) {
 		report(0,
 		       "io_int_param: %x differs from subsys_id_word: %x",
-		       lowcore_ptr->io_int_param, sid);
+		       lowcore_ptr->io_int_param, irq->sid);
 		goto pop;
 	}
 	report_prefix_pop();
 
 	report_prefix_push("tsch");
-	ret = tsch(sid, &irb);
+	ret = tsch(irq->sid, &irq->irb);
 	switch (ret) {
 	case 1:
-		dump_irb(&irb);
-		flags = dump_scsw_flags(irb.scsw.ctrl);
-		report(0,
-		       "I/O interrupt, but tsch returns CC 1 for subchannel %08x. SCSW flags: %s",
-		       sid, flags);
+		report_info("no status pending on %08x : %s", irq->sid,
+			    dump_scsw_flags(irq->irb.scsw.ctrl));
 		break;
 	case 2:
 		report(0, "tsch returns unexpected CC 2");
 		break;
 	case 3:
-		report(0, "tsch reporting sch %08x as not operational", sid);
+		report(0, "tsch reporting sch %08x as not operational", irq->sid);
 		break;
 	case 0:
 		/* Stay humble on success */
+		save_irq(irq);
 		break;
 	}
 pop:
@@ -498,47 +540,70 @@ struct ccw1 *ccw_alloc(int code, void *data, int count, unsigned char flags)
 int wait_and_check_io_completion(int schid)
 {
 	int ret = 0;
-
-	wait_for_interrupt(PSW_MASK_IO);
+	struct irq_entry *irq = NULL;
 
 	report_prefix_push("check I/O completion");
 
-	if (lowcore_ptr->io_int_param != schid) {
+	disable_io_irq();
+	irq = get_irq();
+	while (!irq) {
+		wait_for_interrupt(PSW_MASK_IO);
+		disable_io_irq();
+		irq = get_irq();
+		report_info("next try");
+	}
+	enable_io_irq();
+
+	assert(irq);
+
+	if (irq->sid != schid) {
 		report(0, "interrupt parameter: expected %08x got %08x",
-		       schid, lowcore_ptr->io_int_param);
+		       schid, irq->sid);
 		ret = -1;
 		goto end;
 	}
 
 	/* Verify that device status is valid */
-	if (!(irb.scsw.ctrl & SCSW_SC_PENDING)) {
-		report(0, "No status pending after interrupt. Subch Ctrl: %08x",
-		       irb.scsw.ctrl);
-		ret = -1;
+	if (!(irq->irb.scsw.ctrl & SCSW_SC_PENDING)) {
+		ret = 0;
 		goto end;
 	}
 
-	if (!(irb.scsw.ctrl & (SCSW_SC_SECONDARY | SCSW_SC_PRIMARY))) {
+	/* clear and halt pending are valid even without secondary or primary status */
+	if (irq->irb.scsw.ctrl & (SCSW_FC_CLEAR | SCSW_FC_HALT)) {
+		ret = 0;
+		goto end;
+	}
+
+	/* For start pending we need at least one of primary or secondary status */
+	if (!(irq->irb.scsw.ctrl & (SCSW_SC_SECONDARY | SCSW_SC_PRIMARY))) {
 		report(0, "Primary or secondary status missing. Subch Ctrl: %08x",
-		       irb.scsw.ctrl);
+		       irq->irb.scsw.ctrl);
 		ret = -1;
 		goto end;
 	}
 
-	if (!(irb.scsw.dev_stat & (SCSW_DEVS_DEV_END | SCSW_DEVS_SCH_END))) {
+	/* For start pending we also need to have device or channel end information */
+	if (!(irq->irb.scsw.dev_stat & (SCSW_DEVS_DEV_END | SCSW_DEVS_SCH_END))) {
 		report(0, "No device end or sch end. Dev. status: %02x",
-		       irb.scsw.dev_stat);
+		       irq->irb.scsw.dev_stat);
 		ret = -1;
 		goto end;
 	}
 
-	if (irb.scsw.sch_stat & ~SCSW_SCHS_IL) {
-		report_info("Unexpected Subch. status %02x", irb.scsw.sch_stat);
+	/* We only accept the SubCHannel Status for Illegal Length */
+	if (irq->irb.scsw.sch_stat & ~SCSW_SCHS_IL) {
+		report_info("Unexpected Subch. status %02x",
+			    irq->irb.scsw.sch_stat);
 		ret = -1;
 		goto end;
 	}
 
 end:
+	if (ret)
+		dump_irb(&irq->irb);
+
+	put_irq(irq);
 	report_prefix_pop();
 	return ret;
 }
-- 
2.17.1