Re: [kvm-unit-tests PATCH v3 6/6] s390x: add a test for SIE without MSO/MSL

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On 6/1/23 09:02, Nico Boehr wrote:
Since we now have the ability to run guests without MSO/MSL, add a test
to make sure this doesn't break.

Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
---
  s390x/Makefile             |   2 +
  s390x/sie-dat.c            | 120 +++++++++++++++++++++++++++++++++++++
  s390x/snippets/c/sie-dat.c |  58 ++++++++++++++++++
  s390x/unittests.cfg        |   3 +
  4 files changed, 183 insertions(+)
  create mode 100644 s390x/sie-dat.c
  create mode 100644 s390x/snippets/c/sie-dat.c

diff --git a/s390x/Makefile b/s390x/Makefile
index a80db538810e..4921669ee4c3 100644
--- a/s390x/Makefile
+++ b/s390x/Makefile
@@ -40,6 +40,7 @@ tests += $(TEST_DIR)/panic-loop-pgm.elf
  tests += $(TEST_DIR)/migration-sck.elf
  tests += $(TEST_DIR)/exittime.elf
  tests += $(TEST_DIR)/ex.elf
+tests += $(TEST_DIR)/sie-dat.elf
pv-tests += $(TEST_DIR)/pv-diags.elf @@ -120,6 +121,7 @@ snippet_lib = $(snippet_asmlib) lib/auxinfo.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)/sie-dat.elf: snippets = $(SNIPPET_DIR)/c/sie-dat.gbin
  $(TEST_DIR)/spec_ex-sie.elf: snippets = $(SNIPPET_DIR)/c/spec_ex.gbin
$(TEST_DIR)/pv-diags.elf: pv-snippets += $(SNIPPET_DIR)/asm/snippet-pv-diag-yield.gbin
diff --git a/s390x/sie-dat.c b/s390x/sie-dat.c
new file mode 100644
index 000000000000..c490a2aa825c
--- /dev/null
+++ b/s390x/sie-dat.c
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Tests SIE with paging.
+ *
+ * Copyright 2023 IBM Corp.
+ *
+ * Authors:
+ *    Nico Boehr <nrb@xxxxxxxxxxxxx>
+ */
+#include <libcflat.h>
+#include <vmalloc.h>
+#include <asm/asm-offsets.h>

I only did a cursory glance and wasn't able to see a use for this include.

+#include <asm-generic/barrier.h>
+#include <asm/pgtable.h>
+#include <mmu.h>
+#include <asm/page.h>
+#include <asm/facility.h>

The sclp.h include should be enough, no?
You're not using test_facility() as far as I can see.

+#include <asm/interrupt.h>
+#include <asm/mem.h>
+#include <alloc_page.h>
+#include <sclp.h> > +#include <sie.h>
+#include <snippet.h>
+
+static struct vm vm;
+static pgd_t *guest_root;
+
+/* keep in sync with TEST_PAGE_COUNT in s390x/snippets/c/sie-dat.c */
+#define GUEST_TEST_PAGE_COUNT 10
+
+/* keep in sync with TOTAL_PAGE_COUNT in s390x/snippets/c/sie-dat.c */
+#define GUEST_TOTAL_PAGE_COUNT 256
+
+static void test_sie_dat(void)
+{
+	uint8_t r1;
+	bool contents_match;
+	uint64_t test_page_gpa, test_page_hpa;
+	uint8_t *test_page_hva;
+
+	/* guest will tell us the guest physical address of the test buffer */
+	sie(&vm);
+
+	r1 = (vm.sblk->ipa & 0xf0) >> 4;
+	test_page_gpa = vm.save_area.guest.grs[r1];
+	test_page_hpa = virt_to_pte_phys(guest_root, (void*)test_page_gpa);
+	test_page_hva = __va(test_page_hpa);
+	report(vm.sblk->icptcode == ICPT_INST &&
+	       (vm.sblk->ipa & 0xFF00) == 0x8300 && vm.sblk->ipb == 0x9c0000,
+	       "test buffer gpa=0x%lx hva=%p", test_page_gpa, test_page_hva);

You could rebase on my pv_icptdata.h patch.
Also the report string and boolean don't really relate to each other.

Not every exit needs to be a report.
Some should rather be asserts() or report_info()s.

+
+	/* guest will now write to the test buffer and we verify the contents */
+	sie(&vm);
+	report(vm.sblk->icptcode == ICPT_INST &&
+	       vm.sblk->ipa == 0x8300 && vm.sblk->ipb == 0x440000,
+	       "guest wrote to test buffer");

Yup pv_icptdata.h

+
+	contents_match = true;
+	for (unsigned int i = 0; i < GUEST_TEST_PAGE_COUNT; i++) {
+		uint8_t expected_val = 42 + i;

Just because you can doesn't mean that you have to.
At least leave a \n when declaring new variables...

+		if (test_page_hva[i * PAGE_SIZE] != expected_val) {
+			report_fail("page %u mismatch actual_val=%x expected_val=%x",
+				    i, test_page_hva[i], expected_val);
+			contents_match = false;
+		}
+	}
+	report(contents_match, "test buffer contents match");
+
+	/* the guest will now write to an unmapped address and we check that this causes a segment translation exception */
+	report_prefix_push("guest write to unmapped");
+	expect_pgm_int();
+	sie(&vm);
+	check_pgm_int_code(PGM_INT_CODE_SEGMENT_TRANSLATION);
+	report_prefix_pop();
+}
+

[...]

+}
diff --git a/s390x/snippets/c/sie-dat.c b/s390x/snippets/c/sie-dat.c
new file mode 100644
index 000000000000..e156d0c36c4c
--- /dev/null
+++ b/s390x/snippets/c/sie-dat.c
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Snippet used by the sie-dat.c test to verify paging without MSO/MSL
+ *
+ * Copyright (c) 2023 IBM Corp
+ *
+ * Authors:
+ *  Nico Boehr <nrb@xxxxxxxxxxxxx>
+ */
+#include <stddef.h>
+#include <inttypes.h>
+#include <string.h>
+#include <asm-generic/page.h>
+
+/* keep in sync with GUEST_TEST_PAGE_COUNT in s390x/sie-dat.c */
+#define TEST_PAGE_COUNT 10
+static uint8_t test_page[TEST_PAGE_COUNT * PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));
+
+/* keep in sync with GUEST_TOTAL_PAGE_COUNT in s390x/sie-dat.c */
+#define TOTAL_PAGE_COUNT 256
+
+static inline void force_exit(void)
+{
+	asm volatile("diag	0,0,0x44\n");
+}
+
+static inline void force_exit_value(uint64_t val)
+{
+	asm volatile(
+		"diag	%[val],0,0x9c\n"
+		: : [val] "d"(val)
+	);
+}

It feels like these need to go into a snippet lib.

+
+__attribute__((section(".text"))) int main(void)

The attribute shouldn't be needed anymore.

+{
+	uint8_t *invalid_ptr;
+
+	memset(test_page, 0, sizeof(test_page));
+	/* tell the host the page's physical address (we're running DAT off) */
+	force_exit_value((uint64_t)test_page);
+
+	/* write some value to the page so the host can verify it */
+	for (size_t i = 0; i < TEST_PAGE_COUNT; i++)

Why is i a size_t type?

+		test_page[i * PAGE_SIZE] = 42 + i;
+
+	/* indicate we've written all pages */
+	force_exit();
+
+	/* the first unmapped address */
+	invalid_ptr = (uint8_t *)(TOTAL_PAGE_COUNT * PAGE_SIZE);
+	*invalid_ptr = 42;
+
+	/* indicate we've written the non-allowed page (should never get here) */
+	force_exit();
+
+	return 0;
+}
diff --git a/s390x/unittests.cfg b/s390x/unittests.cfg
index b61faf0737c3..24cd27202a08 100644
--- a/s390x/unittests.cfg
+++ b/s390x/unittests.cfg
@@ -218,3 +218,6 @@ extra_params = -append '--parallel'
[execute]
  file = ex.elf
+
+[sie-dat]
+file = sie-dat.elf




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