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

Claudio Imbrenda
2021-10-05T13:09:40Z

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