Re: [kvm-unit-tests PATCH v4 4/4] s390x: add pgm spec interrupt loop test

[Janosch Frank <frankja@linux.ibm.com>]

On 8/12/22 08:21, Nico Boehr wrote:
> An invalid PSW causes a program interrupt. When an invalid PSW is
> introduced in the pgm_new_psw, an interrupt loop occurs as soon as a
> program interrupt is caused.
> 
> QEMU should detect that and panic the guest, hence add a test for it.
> 
> Signed-off-by: Nico Boehr <nrb@linux.ibm.com>
> ---
>   s390x/Makefile         |  1 +
>   s390x/panic-loop-pgm.c | 39 +++++++++++++++++++++++++++++++++++++++
>   s390x/unittests.cfg    |  6 ++++++
>   3 files changed, 46 insertions(+)
>   create mode 100644 s390x/panic-loop-pgm.c
> 
> diff --git a/s390x/Makefile b/s390x/Makefile
> index e4649da50d9d..66415d0b588d 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -35,6 +35,7 @@ tests += $(TEST_DIR)/pv-attest.elf
>   tests += $(TEST_DIR)/migration-cmm.elf
>   tests += $(TEST_DIR)/migration-skey.elf
>   tests += $(TEST_DIR)/panic-loop-extint.elf
> +tests += $(TEST_DIR)/panic-loop-pgm.elf
>   
>   pv-tests += $(TEST_DIR)/pv-diags.elf
>   
> diff --git a/s390x/panic-loop-pgm.c b/s390x/panic-loop-pgm.c
> new file mode 100644
> index 000000000000..f3b23d67159c
> --- /dev/null
> +++ b/s390x/panic-loop-pgm.c
> @@ -0,0 +1,39 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * Program interrupt loop test
> + *
> + * Copyright IBM Corp. 2022
> + *
> + * Authors:
> + *  Nico Boehr <nrb@linux.ibm.com>
> + */
> +#include <libcflat.h>
> +#include <bitops.h>
> +#include <asm/interrupt.h>
> +#include <asm/barrier.h>
> +#include <hardware.h>
> +
> +int main(void)
> +{
> +	report_prefix_push("panic-loop-pgm");
> +
> +	if (!host_is_qemu() || host_is_tcg()) {
> +		report_skip("QEMU-KVM-only test");
> +		goto out;
> +	}
> +
> +	expect_pgm_int();
> +	/* bit 12 set is invalid */
> +	lowcore.pgm_new_psw.mask = extract_psw_mask() | BIT(63 - 12);
> +	mb();
> +
> +	/* cause a pgm int */
> +	*((int *)-4) = 0x42;
> +	mb();

Hmmmmm, do we have a way to cause a pgm which looks nicer and is easier 
to understand?

We could set bit 12 in the current PSW as well or drop into problem mode 
and try a lctrlg.

> +
> +	report_fail("survived pgmint loop");

Space between pgm and int?

> +
> +out:
> +	report_prefix_pop();
> +	return report_summary();
> +}
> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index b1b25f118ff6..f9f102abfa89 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -191,3 +191,9 @@ file = panic-loop-extint.elf
>   groups = panic
>   accel = kvm
>   timeout = 5
> +
> +[panic-loop-pgm]
> +file = panic-loop-pgm.elf
> +groups = panic
> +accel = kvm
> +timeout = 5