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From:   Thomas Huth <thuth@redhat.com>
To:     kvm@vger.kernel.org,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>
Cc:     linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-s390@vger.kernel.org, David Hildenbrand <david@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?q?Radim=20Kr=C4=8Dm=C3=A1=C5=99?= <rkrcmar@redhat.com>,
        Shuah Khan <shuah@kernel.org>, Peter Xu <peterx@redhat.com>
Subject: [PATCH 2/2] KVM: selftests: Enable dirty_log_test on s390x
Date:   Tue, 30 Jul 2019 12:01:12 +0200
Message-Id: <20190730100112.18205-3-thuth@redhat.com>
In-Reply-To: <20190730100112.18205-1-thuth@redhat.com>
References: <20190730100112.18205-1-thuth@redhat.com>
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To run the dirty_log_test on s390x, we have to make sure that we
access the dirty log bitmap with little endian byte ordering and
we have to properly align the memslot of the guest.
Also all dirty bits of a segment are set once on s390x when one
of the pages of a segment are written to for the first time, so
we have to make sure that we touch all pages during the first
iteration to keep the test in sync here.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 tools/testing/selftests/kvm/Makefile         |  1 +
 tools/testing/selftests/kvm/dirty_log_test.c | 70 ++++++++++++++++++--
 2 files changed, 66 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index ba7849751989..ac7e63e00fee 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -33,6 +33,7 @@ TEST_GEN_PROGS_aarch64 += dirty_log_test
 TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
 
 TEST_GEN_PROGS_s390x += s390x/sync_regs_test
+TEST_GEN_PROGS_s390x += dirty_log_test
 TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
 
 TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index ceb52b952637..7a1223ad0ff3 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -26,9 +26,22 @@
 /* The memory slot index to track dirty pages */
 #define TEST_MEM_SLOT_INDEX		1
 
+#ifdef __s390x__
+
+/*
+ * On s390x, the ELF program is sometimes linked at 0x80000000, so we can
+ * not use 0x40000000 here without overlapping into that region. Thus let's
+ * use 0xc0000000 as base address there instead.
+ */
+#define DEFAULT_GUEST_TEST_MEM		0xc0000000
+
+#else
+
 /* Default guest test memory offset, 1G */
 #define DEFAULT_GUEST_TEST_MEM		0x40000000
 
+#endif
+
 /* How many pages to dirty for each guest loop */
 #define TEST_PAGES_PER_LOOP		1024
 
@@ -38,6 +51,27 @@
 /* Interval for each host loop (ms) */
 #define TEST_HOST_LOOP_INTERVAL		10UL
 
+/* Dirty bitmaps are always little endian, so we need to swap on big endian */
+#if defined(__s390x__)
+# define BITOP_LE_SWIZZLE	((BITS_PER_LONG-1) & ~0x7)
+# define test_bit_le(nr, addr) \
+	test_bit((nr) ^ BITOP_LE_SWIZZLE, addr)
+# define set_bit_le(nr, addr) \
+	set_bit((nr) ^ BITOP_LE_SWIZZLE, addr)
+# define clear_bit_le(nr, addr) \
+	clear_bit((nr) ^ BITOP_LE_SWIZZLE, addr)
+# define test_and_set_bit_le(nr, addr) \
+	test_and_set_bit((nr) ^ BITOP_LE_SWIZZLE, addr)
+# define test_and_clear_bit_le(nr, addr) \
+	test_and_clear_bit((nr) ^ BITOP_LE_SWIZZLE, addr)
+#else
+# define test_bit_le	test_bit
+# define set_bit_le	set_bit
+# define clear_bit_le	clear_bit
+# define test_and_set_bit_le	test_and_set_bit
+# define test_and_clear_bit_le	test_and_clear_bit
+#endif
+
 /*
  * Guest/Host shared variables. Ensure addr_gva2hva() and/or
  * sync_global_to/from_guest() are used when accessing from
@@ -69,11 +103,25 @@ static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
  */
 static void guest_code(void)
 {
+	uint64_t addr;
 	int i;
 
+#ifdef __s390x__
+	/*
+	 * On s390x, all pages of a 1M segment are initially marked as dirty
+	 * when a page of the segment is written to for the very first time.
+	 * To compensate this specialty in this test, we need to touch all
+	 * pages during the first iteration.
+	 */
+	for (i = 0; i < guest_num_pages; i++) {
+		addr = guest_test_virt_mem + i * guest_page_size;
+		*(uint64_t *)addr = READ_ONCE(iteration);
+	}
+#endif
+
 	while (true) {
 		for (i = 0; i < TEST_PAGES_PER_LOOP; i++) {
-			uint64_t addr = guest_test_virt_mem;
+			addr = guest_test_virt_mem;
 			addr += (READ_ONCE(random_array[i]) % guest_num_pages)
 				* guest_page_size;
 			addr &= ~(host_page_size - 1);
@@ -158,15 +206,15 @@ static void vm_dirty_log_verify(unsigned long *bmap)
 		value_ptr = host_test_mem + page * host_page_size;
 
 		/* If this is a special page that we were tracking... */
-		if (test_and_clear_bit(page, host_bmap_track)) {
+		if (test_and_clear_bit_le(page, host_bmap_track)) {
 			host_track_next_count++;
-			TEST_ASSERT(test_bit(page, bmap),
+			TEST_ASSERT(test_bit_le(page, bmap),
 				    "Page %"PRIu64" should have its dirty bit "
 				    "set in this iteration but it is missing",
 				    page);
 		}
 
-		if (test_bit(page, bmap)) {
+		if (test_bit_le(page, bmap)) {
 			host_dirty_count++;
 			/*
 			 * If the bit is set, the value written onto
@@ -209,7 +257,7 @@ static void vm_dirty_log_verify(unsigned long *bmap)
 				 * should report its dirtyness in the
 				 * next run
 				 */
-				set_bit(page, host_bmap_track);
+				set_bit_le(page, host_bmap_track);
 			}
 		}
 	}
@@ -293,6 +341,10 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
 	 * case where the size is not aligned to 64 pages.
 	 */
 	guest_num_pages = (1ul << (30 - guest_page_shift)) + 16;
+#ifdef __s390x__
+	/* Round up to multiple of 1M (segment size) */
+	guest_num_pages = (guest_num_pages + 0xff) & ~0xffUL;
+#endif
 	host_page_size = getpagesize();
 	host_num_pages = (guest_num_pages * guest_page_size) / host_page_size +
 			 !!((guest_num_pages * guest_page_size) % host_page_size);
@@ -304,6 +356,11 @@ static void run_test(enum vm_guest_mode mode, unsigned long iterations,
 		guest_test_phys_mem = phys_offset;
 	}
 
+#ifdef __s390x__
+	/* Align to 1M (segment size) */
+	guest_test_phys_mem &= ~((1 << 20) - 1);
+#endif
+
 	DEBUG("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
 
 	bmap = bitmap_alloc(host_num_pages);
@@ -454,6 +511,9 @@ int main(int argc, char *argv[])
 		vm_guest_mode_params_init(VM_MODE_P48V48_64K, true, true);
 	}
 #endif
+#ifdef __s390x__
+	vm_guest_mode_params_init(VM_MODE_P40V48_4K, true, true);
+#endif
 
 	while ((opt = getopt(argc, argv, "hi:I:p:m:")) != -1) {
 		switch (opt) {
-- 
2.21.0