x86/kprobes: Fix crash when probing CS CALL instructionsgrafted

When using eBPF to probe CS CALL instructions within a function,
a crash can be triggered.

The eBPF tool probes offset 257 of the __hrtimer_run_queues()
function:

<__hrtimer_run_queues+249>:  nopl   0x0(%rax,%rax,1)
<__hrtimer_run_queues+254>:  mov    %r14,%rdi
<__hrtimer_run_queues+257>:  cs call <__x86_indirect_thunk_r12>
<__hrtimer_run_queues+263>:  mov    %eax,%r12d
<__hrtimer_run_queues+266>:  xchg   %ax,%ax
<__hrtimer_run_queues+268>:  mov    %r13,%rdi

Which triggers this crash:

  BUG: unable to handle page fault for address: 00000000000f41c9
  #PF: supervisor write access in kernel mode
  #PF: error_code(0x0002) - not-present page
  PGD 0 P4D 0
  Oops: 0002 [#1] SMP NOPTI
  CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: P
  RIP: 0010:__hrtimer_run_queues+0x106/0x230

Note that __hrtimer_run_queues+0x106 is __hrtimer_run_queues+262, which is
at the 6th byte of the above CS CALL instruction. Since the CS CALL
instruction occupies 6 bytes, the exception occurred in the middle of that
call instruction.

The root cause is that when using eBPF tools to probe in the middle of a
function, a kprobe with INT3 is used as the underlying implementation.

During single-step emulation of the original CALL instruction,
int3_emulate_call() assumes that the probed CALL instruction is 5 bytes
long. However, the actual CS-prefixed CALL instruction occupies 6 bytes,
so it constructs an incorrect exception return address. When the CPU
returns from the kprobe handler, the next instruction to be executed is at
the address of the last byte of that CS CALL instruction. Coincidentally,
starting from that address, the CPU fetches and decodes a completely
different instruction, which ultimately triggers a kernel crash.

Fix the issue by using the actual instruction length obtained from
the instruction decoder when constructing the exception return
address, rather than relying on the hardcoded CALL_INSN_SIZE macro.

[ mingo: Refined the changelog ]

Fixes: 6256e668b7af ("x86/kprobes: Use int3 instead of debug trap for single-step")
Suggested-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Acked-by: Yafang Shao <laoar.shao@gmail.com>
Acked-by: Borislav Petkov <bp@alien8.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://patch.msgid.link/20260908073742.GA10517@didi-ThinkCentre-M920t-N000

1 files changed, 543 insertions, 0 deletions

diff --git a/arch/powerpc/kvm/test-guest-state-buffer.c b/arch/powerpc/kvm/test-guest-state-buffer.c
new file mode 100644
index 000000000..5ccca3069
--- /dev/null
+++ b/arch/powerpc/kvm/test-guest-state-buffer.c
@@ -0,0 +1,543 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <linux/init.h>
+#include <linux/log2.h>
+#include <kunit/test.h>
+
+#include <asm/guest-state-buffer.h>
+#include <asm/kvm_ppc.h>
+
+static void test_creating_buffer(struct kunit *test)
+{
+	struct kvmppc_gs_buff *gsb;
+	size_t size = 0x100;
+
+	gsb = kvmppc_gsb_new(size, 0, 0, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb);
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb->hdr);
+
+	KUNIT_EXPECT_EQ(test, gsb->capacity, roundup_pow_of_two(size));
+	KUNIT_EXPECT_EQ(test, gsb->len, sizeof(__be32));
+
+	kvmppc_gsb_free(gsb);
+}
+
+static void test_adding_element(struct kunit *test)
+{
+	const struct kvmppc_gs_elem *head, *curr;
+	union {
+		__vector128 v;
+		u64 dw[2];
+	} u;
+	int rem;
+	struct kvmppc_gs_buff *gsb;
+	size_t size = 0x1000;
+	int i, rc;
+	u64 data;
+
+	gsb = kvmppc_gsb_new(size, 0, 0, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb);
+
+	/* Single elements, direct use of __kvmppc_gse_put() */
+	data = 0xdeadbeef;
+	rc = __kvmppc_gse_put(gsb, KVMPPC_GSID_GPR(0), 8, &data);
+	KUNIT_EXPECT_GE(test, rc, 0);
+
+	head = kvmppc_gsb_data(gsb);
+	KUNIT_EXPECT_EQ(test, kvmppc_gse_iden(head), KVMPPC_GSID_GPR(0));
+	KUNIT_EXPECT_EQ(test, kvmppc_gse_len(head), 8);
+	data = 0;
+	memcpy(&data, kvmppc_gse_data(head), 8);
+	KUNIT_EXPECT_EQ(test, data, 0xdeadbeef);
+
+	/* Multiple elements, simple wrapper */
+	rc = kvmppc_gse_put_u64(gsb, KVMPPC_GSID_GPR(1), 0xcafef00d);
+	KUNIT_EXPECT_GE(test, rc, 0);
+
+	u.dw[0] = 0x1;
+	u.dw[1] = 0x2;
+	rc = kvmppc_gse_put_vector128(gsb, KVMPPC_GSID_VSRS(0), &u.v);
+	KUNIT_EXPECT_GE(test, rc, 0);
+	u.dw[0] = 0x0;
+	u.dw[1] = 0x0;
+
+	kvmppc_gsb_for_each_elem(i, curr, gsb, rem) {
+		switch (i) {
+		case 0:
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_iden(curr),
+					KVMPPC_GSID_GPR(0));
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_len(curr), 8);
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_get_be64(curr),
+					0xdeadbeef);
+			break;
+		case 1:
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_iden(curr),
+					KVMPPC_GSID_GPR(1));
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_len(curr), 8);
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_get_u64(curr),
+					0xcafef00d);
+			break;
+		case 2:
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_iden(curr),
+					KVMPPC_GSID_VSRS(0));
+			KUNIT_EXPECT_EQ(test, kvmppc_gse_len(curr), 16);
+			kvmppc_gse_get_vector128(curr, &u.v);
+			KUNIT_EXPECT_EQ(test, u.dw[0], 0x1);
+			KUNIT_EXPECT_EQ(test, u.dw[1], 0x2);
+			break;
+		}
+	}
+	KUNIT_EXPECT_EQ(test, i, 3);
+
+	kvmppc_gsb_reset(gsb);
+	KUNIT_EXPECT_EQ(test, kvmppc_gsb_nelems(gsb), 0);
+	KUNIT_EXPECT_EQ(test, kvmppc_gsb_len(gsb),
+			sizeof(struct kvmppc_gs_header));
+
+	kvmppc_gsb_free(gsb);
+}
+
+static void test_gs_parsing(struct kunit *test)
+{
+	struct kvmppc_gs_elem *gse;
+	struct kvmppc_gs_parser gsp = { 0 };
+	struct kvmppc_gs_buff *gsb;
+	size_t size = 0x1000;
+	u64 tmp1, tmp2;
+
+	gsb = kvmppc_gsb_new(size, 0, 0, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb);
+
+	tmp1 = 0xdeadbeefull;
+	kvmppc_gse_put_u64(gsb, KVMPPC_GSID_GPR(0), tmp1);
+
+	KUNIT_EXPECT_GE(test, kvmppc_gse_parse(&gsp, gsb), 0);
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_GPR(0));
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gse);
+
+	tmp2 = kvmppc_gse_get_u64(gse);
+	KUNIT_EXPECT_EQ(test, tmp2, 0xdeadbeefull);
+
+	kvmppc_gsb_free(gsb);
+}
+
+static void test_gs_bitmap(struct kunit *test)
+{
+	struct kvmppc_gs_bitmap gsbm = { 0 };
+	struct kvmppc_gs_bitmap gsbm1 = { 0 };
+	struct kvmppc_gs_bitmap gsbm2 = { 0 };
+	u16 iden;
+	int i, j;
+
+	i = 0;
+	for (u16 iden = KVMPPC_GSID_HOST_STATE_SIZE;
+	     iden <= KVMPPC_GSID_PROCESS_TABLE; iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	for (u16 iden = KVMPPC_GSID_L0_GUEST_HEAP;
+	     iden <= KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM; iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	for (u16 iden = KVMPPC_GSID_RUN_INPUT; iden <= KVMPPC_GSID_VPA;
+	     iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	for (u16 iden = KVMPPC_GSID_GPR(0); iden <= KVMPPC_GSE_DW_REGS_END; iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	for (u16 iden = KVMPPC_GSID_CR; iden <= KVMPPC_GSID_PSPB; iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	for (u16 iden = KVMPPC_GSID_VSRS(0); iden <= KVMPPC_GSID_VSRS(63);
+	     iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	for (u16 iden = KVMPPC_GSID_HDAR; iden <= KVMPPC_GSID_ASDR; iden++) {
+		kvmppc_gsbm_set(&gsbm, iden);
+		kvmppc_gsbm_set(&gsbm1, iden);
+		KUNIT_EXPECT_TRUE(test, kvmppc_gsbm_test(&gsbm, iden));
+		kvmppc_gsbm_clear(&gsbm, iden);
+		KUNIT_EXPECT_FALSE(test, kvmppc_gsbm_test(&gsbm, iden));
+		i++;
+	}
+
+	j = 0;
+	kvmppc_gsbm_for_each(&gsbm1, iden)
+	{
+		kvmppc_gsbm_set(&gsbm2, iden);
+		j++;
+	}
+	KUNIT_EXPECT_EQ(test, i, j);
+	KUNIT_EXPECT_MEMEQ(test, &gsbm1, &gsbm2, sizeof(gsbm1));
+}
+
+struct kvmppc_gs_msg_test1_data {
+	u64 a;
+	u32 b;
+	struct kvmppc_gs_part_table c;
+	struct kvmppc_gs_proc_table d;
+	struct kvmppc_gs_buff_info e;
+};
+
+static size_t test1_get_size(struct kvmppc_gs_msg *gsm)
+{
+	size_t size = 0;
+	u16 ids[] = {
+		KVMPPC_GSID_PARTITION_TABLE,
+		KVMPPC_GSID_PROCESS_TABLE,
+		KVMPPC_GSID_RUN_INPUT,
+		KVMPPC_GSID_GPR(0),
+		KVMPPC_GSID_CR,
+	};
+
+	for (int i = 0; i < ARRAY_SIZE(ids); i++)
+		size += kvmppc_gse_total_size(kvmppc_gsid_size(ids[i]));
+	return size;
+}
+
+static int test1_fill_info(struct kvmppc_gs_buff *gsb,
+			   struct kvmppc_gs_msg *gsm)
+{
+	struct kvmppc_gs_msg_test1_data *data = gsm->data;
+
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_GPR(0)))
+		kvmppc_gse_put_u64(gsb, KVMPPC_GSID_GPR(0), data->a);
+
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_CR))
+		kvmppc_gse_put_u32(gsb, KVMPPC_GSID_CR, data->b);
+
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_PARTITION_TABLE))
+		kvmppc_gse_put_part_table(gsb, KVMPPC_GSID_PARTITION_TABLE,
+					  data->c);
+
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_PROCESS_TABLE))
+		kvmppc_gse_put_proc_table(gsb, KVMPPC_GSID_PARTITION_TABLE,
+					  data->d);
+
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_RUN_INPUT))
+		kvmppc_gse_put_buff_info(gsb, KVMPPC_GSID_RUN_INPUT, data->e);
+
+	return 0;
+}
+
+static int test1_refresh_info(struct kvmppc_gs_msg *gsm,
+			      struct kvmppc_gs_buff *gsb)
+{
+	struct kvmppc_gs_parser gsp = { 0 };
+	struct kvmppc_gs_msg_test1_data *data = gsm->data;
+	struct kvmppc_gs_elem *gse;
+	int rc;
+
+	rc = kvmppc_gse_parse(&gsp, gsb);
+	if (rc < 0)
+		return rc;
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_GPR(0));
+	if (gse)
+		data->a = kvmppc_gse_get_u64(gse);
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_CR);
+	if (gse)
+		data->b = kvmppc_gse_get_u32(gse);
+
+	return 0;
+}
+
+static struct kvmppc_gs_msg_ops gs_msg_test1_ops = {
+	.get_size = test1_get_size,
+	.fill_info = test1_fill_info,
+	.refresh_info = test1_refresh_info,
+};
+
+static void test_gs_msg(struct kunit *test)
+{
+	struct kvmppc_gs_msg_test1_data test1_data = {
+		.a = 0xdeadbeef,
+		.b = 0x1,
+	};
+	struct kvmppc_gs_msg *gsm;
+	struct kvmppc_gs_buff *gsb;
+
+	gsm = kvmppc_gsm_new(&gs_msg_test1_ops, &test1_data, GSM_SEND,
+			     GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsm);
+
+	gsb = kvmppc_gsb_new(kvmppc_gsm_size(gsm), 0, 0, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_PARTITION_TABLE);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_PROCESS_TABLE);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_RUN_INPUT);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_GPR(0));
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_CR);
+
+	kvmppc_gsm_fill_info(gsm, gsb);
+
+	memset(&test1_data, 0, sizeof(test1_data));
+
+	kvmppc_gsm_refresh_info(gsm, gsb);
+	KUNIT_EXPECT_EQ(test, test1_data.a, 0xdeadbeef);
+	KUNIT_EXPECT_EQ(test, test1_data.b, 0x1);
+
+	kvmppc_gsm_free(gsm);
+}
+
+/* Test data struct for hostwide/L0 counters */
+struct kvmppc_gs_msg_test_hostwide_data {
+	u64 guest_heap;
+	u64 guest_heap_max;
+	u64 guest_pgtable_size;
+	u64 guest_pgtable_size_max;
+	u64 guest_pgtable_reclaim;
+};
+
+static size_t test_hostwide_get_size(struct kvmppc_gs_msg *gsm)
+
+{
+	size_t size = 0;
+	u16 ids[] = {
+		KVMPPC_GSID_L0_GUEST_HEAP,
+		KVMPPC_GSID_L0_GUEST_HEAP_MAX,
+		KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE,
+		KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX,
+		KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM
+	};
+
+	for (int i = 0; i < ARRAY_SIZE(ids); i++)
+		size += kvmppc_gse_total_size(kvmppc_gsid_size(ids[i]));
+	return size;
+}
+
+static int test_hostwide_fill_info(struct kvmppc_gs_buff *gsb,
+				   struct kvmppc_gs_msg *gsm)
+{
+	struct kvmppc_gs_msg_test_hostwide_data *data = gsm->data;
+
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_L0_GUEST_HEAP))
+		kvmppc_gse_put_u64(gsb, KVMPPC_GSID_L0_GUEST_HEAP,
+				   data->guest_heap);
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_L0_GUEST_HEAP_MAX))
+		kvmppc_gse_put_u64(gsb, KVMPPC_GSID_L0_GUEST_HEAP_MAX,
+				   data->guest_heap_max);
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE))
+		kvmppc_gse_put_u64(gsb, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE,
+				   data->guest_pgtable_size);
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX))
+		kvmppc_gse_put_u64(gsb, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX,
+				   data->guest_pgtable_size_max);
+	if (kvmppc_gsm_includes(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM))
+		kvmppc_gse_put_u64(gsb, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM,
+				   data->guest_pgtable_reclaim);
+
+	return 0;
+}
+
+static int test_hostwide_refresh_info(struct kvmppc_gs_msg *gsm,
+				      struct kvmppc_gs_buff *gsb)
+{
+	struct kvmppc_gs_parser gsp = { 0 };
+	struct kvmppc_gs_msg_test_hostwide_data *data = gsm->data;
+	struct kvmppc_gs_elem *gse;
+	int rc;
+
+	rc = kvmppc_gse_parse(&gsp, gsb);
+	if (rc < 0)
+		return rc;
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_HEAP);
+	if (gse)
+		data->guest_heap = kvmppc_gse_get_u64(gse);
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_HEAP_MAX);
+	if (gse)
+		data->guest_heap_max = kvmppc_gse_get_u64(gse);
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE);
+	if (gse)
+		data->guest_pgtable_size = kvmppc_gse_get_u64(gse);
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX);
+	if (gse)
+		data->guest_pgtable_size_max = kvmppc_gse_get_u64(gse);
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM);
+	if (gse)
+		data->guest_pgtable_reclaim = kvmppc_gse_get_u64(gse);
+
+	return 0;
+}
+
+static struct kvmppc_gs_msg_ops gs_msg_test_hostwide_ops = {
+	.get_size = test_hostwide_get_size,
+	.fill_info = test_hostwide_fill_info,
+	.refresh_info = test_hostwide_refresh_info,
+};
+
+static void test_gs_hostwide_msg(struct kunit *test)
+{
+	struct kvmppc_gs_msg_test_hostwide_data test_data = {
+		.guest_heap = 0xdeadbeef,
+		.guest_heap_max = ~0ULL,
+		.guest_pgtable_size = 0xff,
+		.guest_pgtable_size_max = 0xffffff,
+		.guest_pgtable_reclaim = 0xdeadbeef,
+	};
+	struct kvmppc_gs_msg *gsm;
+	struct kvmppc_gs_buff *gsb;
+
+	gsm = kvmppc_gsm_new(&gs_msg_test_hostwide_ops, &test_data, GSM_SEND,
+			     GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsm);
+
+	gsb = kvmppc_gsb_new(kvmppc_gsm_size(gsm), 0, 0, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_HEAP);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_HEAP_MAX);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX);
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM);
+
+	kvmppc_gsm_fill_info(gsm, gsb);
+
+	memset(&test_data, 0, sizeof(test_data));
+
+	kvmppc_gsm_refresh_info(gsm, gsb);
+	KUNIT_EXPECT_EQ(test, test_data.guest_heap, 0xdeadbeef);
+	KUNIT_EXPECT_EQ(test, test_data.guest_heap_max, ~0ULL);
+	KUNIT_EXPECT_EQ(test, test_data.guest_pgtable_size, 0xff);
+	KUNIT_EXPECT_EQ(test, test_data.guest_pgtable_size_max, 0xffffff);
+	KUNIT_EXPECT_EQ(test, test_data.guest_pgtable_reclaim, 0xdeadbeef);
+
+	kvmppc_gsm_free(gsm);
+}
+
+/* Test if the H_GUEST_GET_STATE for hostwide counters works */
+static void test_gs_hostwide_counters(struct kunit *test)
+{
+	struct kvmppc_gs_msg_test_hostwide_data test_data;
+	struct kvmppc_gs_parser gsp = { 0 };
+
+	struct kvmppc_gs_msg *gsm;
+	struct kvmppc_gs_buff *gsb;
+	struct kvmppc_gs_elem *gse;
+	int rc;
+
+	if (!kvmhv_on_pseries())
+		kunit_skip(test, "This test need a kmv-hv guest");
+
+	gsm = kvmppc_gsm_new(&gs_msg_test_hostwide_ops, &test_data, GSM_SEND,
+			     GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsm);
+
+	gsb = kvmppc_gsb_new(kvmppc_gsm_size(gsm), 0, 0, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, gsb);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_HEAP);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_HEAP_MAX);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX);
+
+	kvmppc_gsm_include(gsm, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM);
+
+	kvmppc_gsm_fill_info(gsm, gsb);
+
+	/* With HOST_WIDE flags guestid and vcpuid will be ignored */
+	rc = kvmppc_gsb_recv(gsb, KVMPPC_GS_FLAGS_HOST_WIDE);
+	KUNIT_ASSERT_EQ(test, rc, 0);
+
+	/* Parse the guest state buffer is successful */
+	rc = kvmppc_gse_parse(&gsp, gsb);
+	KUNIT_ASSERT_EQ(test, rc, 0);
+
+	/* Parse the GSB and get the counters */
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_HEAP);
+	KUNIT_ASSERT_NOT_NULL_MSG(test, gse, "L0 Heap counter missing");
+	kunit_info(test, "Guest Heap Size=%llu bytes",
+		   kvmppc_gse_get_u64(gse));
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_HEAP_MAX);
+	KUNIT_ASSERT_NOT_NULL_MSG(test, gse, "L0 Heap counter max missing");
+	kunit_info(test, "Guest Heap Size Max=%llu bytes",
+		   kvmppc_gse_get_u64(gse));
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE);
+	KUNIT_ASSERT_NOT_NULL_MSG(test, gse, "L0 page-table size missing");
+	kunit_info(test, "Guest Page-table Size=%llu bytes",
+		   kvmppc_gse_get_u64(gse));
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_PGTABLE_SIZE_MAX);
+	KUNIT_ASSERT_NOT_NULL_MSG(test, gse, "L0 page-table size-max missing");
+	kunit_info(test, "Guest Page-table Size Max=%llu bytes",
+		   kvmppc_gse_get_u64(gse));
+
+	gse = kvmppc_gsp_lookup(&gsp, KVMPPC_GSID_L0_GUEST_PGTABLE_RECLAIM);
+	KUNIT_ASSERT_NOT_NULL_MSG(test, gse, "L0 page-table reclaim size missing");
+	kunit_info(test, "Guest Page-table Reclaim Size=%llu bytes",
+		   kvmppc_gse_get_u64(gse));
+
+	kvmppc_gsm_free(gsm);
+	kvmppc_gsb_free(gsb);
+}
+
+static struct kunit_case guest_state_buffer_testcases[] = {
+	KUNIT_CASE(test_creating_buffer),
+	KUNIT_CASE(test_adding_element),
+	KUNIT_CASE(test_gs_bitmap),
+	KUNIT_CASE(test_gs_parsing),
+	KUNIT_CASE(test_gs_msg),
+	KUNIT_CASE(test_gs_hostwide_msg),
+	KUNIT_CASE(test_gs_hostwide_counters),
+	{}
+};
+
+static struct kunit_suite guest_state_buffer_test_suite = {
+	.name = "guest_state_buffer_test",
+	.test_cases = guest_state_buffer_testcases,
+};
+
+kunit_test_suites(&guest_state_buffer_test_suite);
+
+MODULE_DESCRIPTION("KUnit tests for Guest State Buffer APIs");
+MODULE_LICENSE("GPL");