Re: [kvm-unit-tests PATCH v2 2/2] s390x: Add specification exception interception test

[Claudio Imbrenda <imbrenda@linux.ibm.com>]

On Tue,  5 Oct 2021 11:11:53 +0200
Janis Schoetterl-Glausch <scgl@linux.ibm.com> wrote:

> Check that specification exceptions cause intercepts when
> specification exception interpretation is off.
> Check that specification exceptions caused by program new PSWs
> cause interceptions.
> We cannot assert that non program new PSW specification exceptions
> are interpreted because whether interpretation occurs or not is
> configuration dependent.
> 
> Signed-off-by: Janis Schoetterl-Glausch <scgl@linux.ibm.com>
> ---
>  s390x/Makefile             |  2 +
>  lib/s390x/sie.h            |  1 +
>  s390x/snippets/c/spec_ex.c | 20 +++++++++
>  s390x/spec_ex-sie.c        | 83 ++++++++++++++++++++++++++++++++++++++
>  s390x/unittests.cfg        |  3 ++
>  5 files changed, 109 insertions(+)
>  create mode 100644 s390x/snippets/c/spec_ex.c
>  create mode 100644 s390x/spec_ex-sie.c
> 
> diff --git a/s390x/Makefile b/s390x/Makefile
> index ef8041a..7198882 100644
> --- a/s390x/Makefile
> +++ b/s390x/Makefile
> @@ -24,6 +24,7 @@ tests += $(TEST_DIR)/mvpg.elf
>  tests += $(TEST_DIR)/uv-host.elf
>  tests += $(TEST_DIR)/edat.elf
>  tests += $(TEST_DIR)/mvpg-sie.elf
> +tests += $(TEST_DIR)/spec_ex-sie.elf
>  
>  tests_binary = $(patsubst %.elf,%.bin,$(tests))
>  ifneq ($(HOST_KEY_DOCUMENT),)
> @@ -85,6 +86,7 @@ snippet_asmlib = $(SNIPPET_DIR)/c/cstart.o
>  # perquisites (=guests) for the snippet hosts.
>  # $(TEST_DIR)/<snippet-host>.elf: snippets = $(SNIPPET_DIR)/<c/asm>/<snippet>.gbin
>  $(TEST_DIR)/mvpg-sie.elf: snippets = $(SNIPPET_DIR)/c/mvpg-snippet.gbin
> +$(TEST_DIR)/spec_ex-sie.elf: snippets = $(SNIPPET_DIR)/c/spec_ex.gbin
>  
>  $(SNIPPET_DIR)/asm/%.gbin: $(SNIPPET_DIR)/asm/%.o $(FLATLIBS)
>  	$(OBJCOPY) -O binary $(patsubst %.gbin,%.o,$@) $@
> diff --git a/lib/s390x/sie.h b/lib/s390x/sie.h
> index ca514ef..7ef7251 100644
> --- a/lib/s390x/sie.h
> +++ b/lib/s390x/sie.h
> @@ -98,6 +98,7 @@ struct kvm_s390_sie_block {
>  	uint8_t		fpf;			/* 0x0060 */
>  #define ECB_GS		0x40
>  #define ECB_TE		0x10
> +#define ECB_SPECI	0x08
>  #define ECB_SRSI	0x04
>  #define ECB_HOSTPROTINT	0x02
>  	uint8_t		ecb;			/* 0x0061 */
> diff --git a/s390x/snippets/c/spec_ex.c b/s390x/snippets/c/spec_ex.c
> new file mode 100644
> index 0000000..bdba4f4
> --- /dev/null
> +++ b/s390x/snippets/c/spec_ex.c
> @@ -0,0 +1,20 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * © Copyright IBM Corp. 2021
> + *
> + * Snippet used by specification exception interception test.
> + */
> +#include <stdint.h>
> +#include <asm/arch_def.h>
> +
> +__attribute__((section(".text"))) int main(void)
> +{
> +	struct lowcore *lowcore = (struct lowcore *) 0;
> +	uint64_t bad_psw = 0;
> +
> +	/* PSW bit 12 has no name or meaning and must be 0 */
> +	lowcore->pgm_new_psw.mask = 1UL << (63 - 12);

you can use the BIT or BIT_ULL macro

> +	lowcore->pgm_new_psw.addr = 0xdeadbeee;

if the system is broken, it might actually jump at that address; in
that case, will the test fail?

> +	asm volatile ("lpsw %0" :: "Q"(bad_psw));
> +	return 0;
> +}
> diff --git a/s390x/spec_ex-sie.c b/s390x/spec_ex-sie.c
> new file mode 100644
> index 0000000..b7e79de
> --- /dev/null
> +++ b/s390x/spec_ex-sie.c
> @@ -0,0 +1,83 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * © Copyright IBM Corp. 2021
> + *
> + * Specification exception interception test.
> + * Checks that specification exception interceptions occur as expected when
> + * specification exception interpretation is off/on.
> + */
> +#include <libcflat.h>
> +#include <sclp.h>
> +#include <asm/page.h>
> +#include <asm/arch_def.h>
> +#include <alloc_page.h>
> +#include <vm.h>
> +#include <sie.h>
> +
> +static struct vm vm;
> +extern const char _binary_s390x_snippets_c_spec_ex_gbin_start[];
> +extern const char _binary_s390x_snippets_c_spec_ex_gbin_end[];
> +
> +static void setup_guest(void)
> +{
> +	char *guest;
> +	int binary_size = ((uintptr_t)_binary_s390x_snippets_c_spec_ex_gbin_end -
> +			   (uintptr_t)_binary_s390x_snippets_c_spec_ex_gbin_start);
> +
> +	setup_vm();
> +	guest = alloc_pages(8);
> +	memcpy(guest, _binary_s390x_snippets_c_spec_ex_gbin_start, binary_size);
> +	sie_guest_create(&vm, (uint64_t) guest, HPAGE_SIZE);
> +}
> +
> +static void reset_guest(void)
> +{
> +	vm.sblk->gpsw.addr = PAGE_SIZE * 4;
> +	vm.sblk->gpsw.mask = PSW_MASK_64;
> +	vm.sblk->icptcode = 0;
> +}
> +
> +static void test_spec_ex_sie(void)
> +{
> +	setup_guest();
> +
> +	report_prefix_push("SIE spec ex interpretation");
> +	report_prefix_push("off");
> +	reset_guest();
> +	sie(&vm);
> +	/* interpretation off -> initial exception must cause interception */
> +	report(vm.sblk->icptcode == ICPT_PROGI
> +	       && vm.sblk->iprcc == PGM_INT_CODE_SPECIFICATION
> +	       && vm.sblk->gpsw.addr != 0xdeadbeee,
> +	       "Received specification exception intercept for initial exception");
> +	report_prefix_pop();
> +
> +	report_prefix_push("on");
> +	vm.sblk->ecb |= ECB_SPECI;
> +	reset_guest();
> +	sie(&vm);
> +	/* interpretation on -> configuration dependent if initial exception causes
> +	 * interception, but invalid new program PSW must
> +	 */
> +	report(vm.sblk->icptcode == ICPT_PROGI
> +	       && vm.sblk->iprcc == PGM_INT_CODE_SPECIFICATION,
> +	       "Received specification exception intercept");
> +	if (vm.sblk->gpsw.addr == 0xdeadbeee)
> +		report_info("Interpreted initial exception, intercepted invalid program new PSW exception");
> +	else
> +		report_info("Did not interpret initial exception");
> +	report_prefix_pop();
> +	report_prefix_pop();
> +}
> +
> +int main(int argc, char **argv)
> +{
> +	if (!sclp_facilities.has_sief2) {
> +		report_skip("SIEF2 facility unavailable");
> +		goto out;
> +	}
> +
> +	test_spec_ex_sie();
> +out:
> +	return report_summary();
> +}
> diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
> index 9e1802f..3b454b7 100644
> --- a/s390x/unittests.cfg
> +++ b/s390x/unittests.cfg
> @@ -109,3 +109,6 @@ file = edat.elf
>  
>  [mvpg-sie]
>  file = mvpg-sie.elf
> +
> +[spec_ex-sie]
> +file = spec_ex-sie.elf