Re: [kvm-unit-tests PATCH v4 8/9] s390x: css: ssch/tsch with sense and interrupt

[Cornelia Huck <cohuck@redhat.com>]

On Wed, 11 Dec 2019 16:46:09 +0100
Pierre Morel <pmorel@linux.ibm.com> wrote:

> When a channel is enabled we can start a SENSE command using the SSCH

s/SENSE/SENSE ID/

SENSE is for getting sense data after a unit check :)

> instruction to recognize the control unit and device.
> 
> This tests the success of SSCH, the I/O interruption and the TSCH
> instructions.
> 
> The test expects a device with a control unit type of 0xC0CA as the
> first subchannel of the CSS.
> 
> Signed-off-by: Pierre Morel <pmorel@linux.ibm.com>
> ---
>  lib/s390x/css.h |  13 ++++
>  s390x/css.c     | 175 ++++++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 188 insertions(+)

> +static void irq_io(void)
> +{
> +	int ret = 0;
> +	char *flags;
> +	int sid;
> +
> +	report_prefix_push("Interrupt");
> +	if (lowcore->io_int_param != CSS_TEST_INT_PARAM) {
> +		report(0, "Bad io_int_param: %x", lowcore->io_int_param);
> +		report_prefix_pop();
> +		return;
> +	}
> +	report_prefix_pop();
> +
> +	report_prefix_push("tsch");
> +	sid = lowcore->subsys_id_word;
> +	ret = tsch(sid, &irb);
> +	switch (ret) {
> +	case 1:
> +		dump_irb(&irb);
> +		flags = dump_scsw_flags(irb.scsw.ctrl);
> +		report(0, "IRB scsw flags: %s", flags);

I guess that should only happen if the I/O interrupt was for another
subchannel, and we only enable one subchannel, right?

Maybe log "I/O interrupt, but sch not status pending: <flags>"? (No
idea how log the logged messages can be for kvm unit tests.)

> +		goto pop;
> +	case 2:
> +		report(0, "TSCH return unexpected CC 2");

s/return/returns/

> +		goto pop;
> +	case 3:
> +		report(0, "Subchannel %08x not operational", sid);
> +		goto pop;
> +	case 0:
> +		/* Stay humble on success */

:)

> +		break;
> +	}
> +pop:
> +	report_prefix_pop();
> +}
> +
> +static int start_subchannel(int code, char *data, int count)
> +{
> +	int ret;
> +	struct pmcw *p = &schib.pmcw;
> +	struct orb *orb_p = &orb[0];
> +
> +	/* Verify that a test subchannel has been set */
> +	if (!test_device_sid) {
> +		report_skip("No device");
> +		return 0;
> +	}
> +
> +	if ((unsigned long)data >= 0x80000000UL) {
> +		report(0, "Data above 2G! %p", data);
> +		return 0;
> +	}
> +
> +	/* Verify that the subchannel has been enabled */
> +	ret = stsch(test_device_sid, &schib);
> +	if (ret) {
> +		report(0, "Err %d on stsch on sid %08x", ret, test_device_sid);
> +		return 0;
> +	}
> +	if (!(p->flags & PMCW_ENABLE)) {
> +		report_skip("Device (sid %08x) not enabled", test_device_sid);
> +		return 0;
> +	}
> +
> +	report_prefix_push("ssch");
> +	/* Build the CCW chain with a single CCW */
> +	ccw[0].code = code;
> +	ccw[0].flags = 0; /* No flags need to be set */
> +	ccw[0].count = count;
> +	ccw[0].data_address = (int)(unsigned long)data;
> +	orb_p->intparm = CSS_TEST_INT_PARAM;
> +	orb_p->ctrl = ORB_F_INIT_IRQ|ORB_F_FORMAT|ORB_F_LPM_DFLT;
> +	if ((unsigned long)&ccw[0] >= 0x80000000UL) {
> +		report(0, "CCW above 2G! %016lx", (unsigned long)&ccw[0]);

Maybe check before filling out the ccw?

> +		report_prefix_pop();
> +		return 0;
> +	}
> +	orb_p->cpa = (unsigned int) (unsigned long)&ccw[0];
> +
> +	ret = ssch(test_device_sid, orb_p);
> +	if (ret) {
> +		report(0, "ssch cc=%d", ret);
> +		report_prefix_pop();
> +		return 0;
> +	}
> +	report_prefix_pop();
> +	return 1;
> +}
> +
> +/*
> + * test_sense
> + * Pre-requisits:
> + * - We need the QEMU PONG device as the first recognized
> + * - device by the enumeration.
> + * - ./s390x-run s390x/css.elf -device ccw-pong,cu_type=0xc0ca
> + */
> +static void test_sense(void)
> +{
> +	int ret;
> +
> +	ret = register_io_int_func(irq_io);
> +	if (ret) {
> +		report(0, "Could not register IRQ handler");
> +		goto unreg_cb;
> +	}
> +
> +	enable_io_irq();
> +	lowcore->io_int_param = 0;
> +
> +	ret = start_subchannel(CCW_CMD_SENSE_ID, buffer, sizeof(senseid));
> +	if (!ret) {
> +		report(0, "start_subchannel failed");
> +		goto unreg_cb;
> +	}
> +
> +	delay(100);
> +	if (lowcore->io_int_param != CSS_TEST_INT_PARAM) {
> +		report(0, "cu_type: expect 0x%08x, got 0x%08x",
> +		       CSS_TEST_INT_PARAM, lowcore->io_int_param);
> +		goto unreg_cb;
> +	}

This still looks like that odd "delay and hope an interrupt has arrived
in the mean time" pattern.

Also, doesn't the interrupt handler check for the intparm already?

> +
> +	senseid.cu_type = buffer[2] | (buffer[1] << 8);

This still looks odd; why not have the ccw fill out the senseid
structure directly?

> +
> +	/* Sense ID is non packed cut_type is at offset +1 byte */

I have trouble parsing this sentence...

> +	if (senseid.cu_type == PONG_CU)
> +		report(1, "cu_type: expect 0x%04x got 0x%04x",
> +		       PONG_CU_TYPE, senseid.cu_type);
> +	else
> +		report(0, "cu_type: expect 0x%04x got 0x%04x",
> +		       PONG_CU_TYPE, senseid.cu_type);

Didn't you want to check for ff in the reserved field as well?

> +
> +unreg_cb:
> +	unregister_io_int_func(irq_io);
> +}
> +
>  static struct {
>  	const char *name;
>  	void (*func)(void);
>  } tests[] = {
>  	{ "enumerate (stsch)", test_enumerate },
>  	{ "enable (msch)", test_enable },
> +	{ "sense (ssch/tsch)", test_sense },
>  	{ NULL, NULL }
>  };
>