2022-05-10 18:54:52

by Steffen Eiden

[permalink] [raw]
Subject: [PATCH v4 0/2] s390: Ultravisor device

This series adds an Ultravisor(UV) device letting the userspace send some
Ultravisor calls to the UV. Currently two calls are supported.
Query Ultravisor Information (QUI) and
Receive Attestation Measurement (Attest[ation]).

The UV device is implemented as a miscdevice accepting only IOCTLs.
The IOCTL cmd specifies the UV call and the IOCTL arg the request
and response data depending on the UV call.
The device driver writes the UV response in the ioctl argument data.

The 'uvdevice' does no checks on the request beside faulty userspace
addresses, if sizes are in a sane range before allocating in kernel space,
and other tests that prevent the system from corruption.
Especially, no checks are made, that will be performed by the UV anyway
(E.g. 'invalid command' in case of attestation on unsupported hardware).
These errors are reported back to userspace using the UV return code
field.

The first patch introduces the new device as a module configured to be
compiled directly into the kernel (y) similar to the s390 SCLP and CHSH
miscdevice modules. The second atch introduces Kselftests which verify error
paths of the ioctl.

@Greg
There is now a userspace tool "pvattest" that uses the new device:
https://github.com/ibm-s390-linux/s390-tools/tree/for-2.22

We are currently discussing some nits regarding the processing
of certificates and the user interface and add the tool to
s390-tools/master afterwards.
However, the interface to the kernel is fixed.
The tool (pvattest) will be in s390-tools 2.22 that accompanies
linux 5.18.
You will be most interested in S390-tools/pvattest/src/uvio.{h,c}
and S390-tools/pvattest/src/pvattest.c

v3->v4:
* Dropped the QUI related patches, as we agreed that we do not want
to expose the QUI-UVC to userspace for now.
* Kconfig option was misplaced inside the S390 TAPE group ->fixed
* Some nits fixed:
* dropped the X from S390X in the uvdevice.h guard
* fixes kernel doc style issue in uvdevice.c

v2->v3:
The main change is that QUI is now introduced after Attestation as we
might not want pick it. Also the Kselftest patch is splitted into
Attestation and QUI so that they can be picked without requiring
QUI support of the uvdevice.

* dropped the Kconfig dependency
* reorganized the series:
- Patch 1 now covers the introduction of the uvdevice and Attestation
- Patch 2 adds QUI to uvdevice
- Patch 3/4 add Kselftests for Attestation and QUI
* fixed some nits
* added some comments

v1->v2:
* ioctl returns -ENOIOCTLCMD in case of a invalid ioctl command
* streamlined reserved field test
* default Kconfig is y instead of m
* improved selftest documentation

Steffen Eiden (2):
drivers/s390/char: Add Ultravisor io device
selftests: drivers/s390x: Add uvdevice tests

MAINTAINERS | 3 +
arch/s390/include/asm/uv.h | 23 +-
arch/s390/include/uapi/asm/uvdevice.h | 51 ++++
drivers/s390/char/Kconfig | 10 +
drivers/s390/char/Makefile | 1 +
drivers/s390/char/uvdevice.c | 264 +++++++++++++++++
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/drivers/.gitignore | 1 +
.../selftests/drivers/s390x/uvdevice/Makefile | 22 ++
.../selftests/drivers/s390x/uvdevice/config | 1 +
.../drivers/s390x/uvdevice/test_uvdevice.c | 276 ++++++++++++++++++
11 files changed, 652 insertions(+), 1 deletion(-)
create mode 100644 arch/s390/include/uapi/asm/uvdevice.h
create mode 100644 drivers/s390/char/uvdevice.c
create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/Makefile
create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/config
create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/test_uvdevice.c

--
2.30.2



2022-05-10 19:48:33

by Steffen Eiden

[permalink] [raw]
Subject: [PATCH v4 2/2] selftests: drivers/s390x: Add uvdevice tests

Adds some selftests to test ioctl error paths of the uv-uapi.
The Kconfig S390_UV_UAPI must be selected and the Ultravisor facility
must be available. The test can be executed by non-root, however, the
uvdevice special file /dev/uv must be accessible for reading and
writing which may imply root privileges.

./test-uv-device
TAP version 13
1..6
# Starting 6 tests from 3 test cases.
# RUN uvio_fixture.att.fault_ioctl_arg ...
# OK uvio_fixture.att.fault_ioctl_arg
ok 1 uvio_fixture.att.fault_ioctl_arg
# RUN uvio_fixture.att.fault_uvio_arg ...
# OK uvio_fixture.att.fault_uvio_arg
ok 2 uvio_fixture.att.fault_uvio_arg
# RUN uvio_fixture.att.inval_ioctl_cb ...
# OK uvio_fixture.att.inval_ioctl_cb
ok 3 uvio_fixture.att.inval_ioctl_cb
# RUN uvio_fixture.att.inval_ioctl_cmd ...
# OK uvio_fixture.att.inval_ioctl_cmd
ok 4 uvio_fixture.att.inval_ioctl_cmd
# RUN attest_fixture.att_inval_request ...
# OK attest_fixture.att_inval_request
ok 5 attest_fixture.att_inval_request
# RUN attest_fixture.att_inval_addr ...
# OK attest_fixture.att_inval_addr
ok 6 attest_fixture.att_inval_addr
# PASSED: 6 / 6 tests passed.
# Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Steffen Eiden <[email protected]>
Acked-by: Janosch Frank <[email protected]>
---
MAINTAINERS | 1 +
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/drivers/.gitignore | 1 +
.../selftests/drivers/s390x/uvdevice/Makefile | 22 ++
.../selftests/drivers/s390x/uvdevice/config | 1 +
.../drivers/s390x/uvdevice/test_uvdevice.c | 276 ++++++++++++++++++
6 files changed, 302 insertions(+)
create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/Makefile
create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/config
create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/test_uvdevice.c

diff --git a/MAINTAINERS b/MAINTAINERS
index b42ab4a35e18..46a9b1467380 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10786,6 +10786,7 @@ F: arch/s390/kernel/uv.c
F: arch/s390/kvm/
F: arch/s390/mm/gmap.c
F: drivers/s390/char/uvdevice.c
+F: tools/testing/selftests/drivers/s390x/uvdevice/
F: tools/testing/selftests/kvm/*/s390x/
F: tools/testing/selftests/kvm/s390x/

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 2319ec87f53d..d6b307371ef7 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -10,6 +10,7 @@ TARGETS += core
TARGETS += cpufreq
TARGETS += cpu-hotplug
TARGETS += drivers/dma-buf
+TARGETS += drivers/s390x/uvdevice
TARGETS += efivarfs
TARGETS += exec
TARGETS += filesystems
diff --git a/tools/testing/selftests/drivers/.gitignore b/tools/testing/selftests/drivers/.gitignore
index ca74f2e1c719..09e23b5afa96 100644
--- a/tools/testing/selftests/drivers/.gitignore
+++ b/tools/testing/selftests/drivers/.gitignore
@@ -1,2 +1,3 @@
# SPDX-License-Identifier: GPL-2.0-only
/dma-buf/udmabuf
+/s390x/uvdevice/test_uvdevice
diff --git a/tools/testing/selftests/drivers/s390x/uvdevice/Makefile b/tools/testing/selftests/drivers/s390x/uvdevice/Makefile
new file mode 100644
index 000000000000..5e701d2708d4
--- /dev/null
+++ b/tools/testing/selftests/drivers/s390x/uvdevice/Makefile
@@ -0,0 +1,22 @@
+include ../../../../../build/Build.include
+
+UNAME_M := $(shell uname -m)
+
+ifneq ($(UNAME_M),s390x)
+nothing:
+.PHONY: all clean run_tests install
+.SILENT:
+else
+
+TEST_GEN_PROGS := test_uvdevice
+
+top_srcdir ?= ../../../../../..
+KSFT_KHDR_INSTALL := 1
+khdr_dir = $(top_srcdir)/usr/include
+LINUX_TOOL_ARCH_INCLUDE = $(top_srcdir)/tools/arch/$(ARCH)/include
+
+CFLAGS += -Wall -Werror -static -I$(khdr_dir) -I$(LINUX_TOOL_ARCH_INCLUDE)
+
+include ../../../lib.mk
+
+endif
diff --git a/tools/testing/selftests/drivers/s390x/uvdevice/config b/tools/testing/selftests/drivers/s390x/uvdevice/config
new file mode 100644
index 000000000000..f28a04b99eff
--- /dev/null
+++ b/tools/testing/selftests/drivers/s390x/uvdevice/config
@@ -0,0 +1 @@
+CONFIG_S390_UV_UAPI=y
diff --git a/tools/testing/selftests/drivers/s390x/uvdevice/test_uvdevice.c b/tools/testing/selftests/drivers/s390x/uvdevice/test_uvdevice.c
new file mode 100644
index 000000000000..ea0cdc37b44f
--- /dev/null
+++ b/tools/testing/selftests/drivers/s390x/uvdevice/test_uvdevice.c
@@ -0,0 +1,276 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * selftest for the Ultravisor UAPI device
+ *
+ * Copyright IBM Corp. 2022
+ * Author(s): Steffen Eiden <[email protected]>
+ */
+
+#include <stdint.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+
+#include <asm/uvdevice.h>
+
+#include "../../../kselftest_harness.h"
+
+#define UV_PATH "/dev/uv"
+#define BUFFER_SIZE 0x200
+FIXTURE(uvio_fixture) {
+ int uv_fd;
+ struct uvio_ioctl_cb uvio_ioctl;
+ uint8_t buffer[BUFFER_SIZE];
+ __u64 fault_page;
+};
+
+FIXTURE_VARIANT(uvio_fixture) {
+ unsigned long ioctl_cmd;
+ uint32_t arg_size;
+};
+
+FIXTURE_VARIANT_ADD(uvio_fixture, att) {
+ .ioctl_cmd = UVIO_IOCTL_ATT,
+ .arg_size = sizeof(struct uvio_attest),
+};
+
+FIXTURE_SETUP(uvio_fixture)
+{
+ self->uv_fd = open(UV_PATH, O_ACCMODE);
+
+ self->uvio_ioctl.argument_addr = (__u64)self->buffer;
+ self->uvio_ioctl.argument_len = variant->arg_size;
+ self->fault_page =
+ (__u64)mmap(NULL, (size_t)getpagesize(), PROT_NONE, MAP_ANONYMOUS, -1, 0);
+}
+
+FIXTURE_TEARDOWN(uvio_fixture)
+{
+ if (self->uv_fd)
+ close(self->uv_fd);
+ munmap((void *)self->fault_page, (size_t)getpagesize());
+}
+
+TEST_F(uvio_fixture, fault_ioctl_arg)
+{
+ int rc, errno_cache;
+
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, NULL);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EFAULT);
+
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, self->fault_page);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EFAULT);
+}
+
+TEST_F(uvio_fixture, fault_uvio_arg)
+{
+ int rc, errno_cache;
+
+ self->uvio_ioctl.argument_addr = 0;
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EFAULT);
+
+ self->uvio_ioctl.argument_addr = self->fault_page;
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EFAULT);
+}
+
+/*
+ * Test to verify that IOCTLs with invalid values in the ioctl_control block
+ * are rejected.
+ */
+TEST_F(uvio_fixture, inval_ioctl_cb)
+{
+ int rc, errno_cache;
+
+ self->uvio_ioctl.argument_len = 0;
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+
+ self->uvio_ioctl.argument_len = (uint32_t)-1;
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+ self->uvio_ioctl.argument_len = variant->arg_size;
+
+ self->uvio_ioctl.flags = (uint32_t)-1;
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+ self->uvio_ioctl.flags = 0;
+
+ memset(self->uvio_ioctl.reserved14, 0xff, sizeof(self->uvio_ioctl.reserved14));
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+
+ memset(&self->uvio_ioctl, 0x11, sizeof(self->uvio_ioctl));
+ rc = ioctl(self->uv_fd, variant->ioctl_cmd, &self->uvio_ioctl);
+ ASSERT_EQ(rc, -1);
+}
+
+TEST_F(uvio_fixture, inval_ioctl_cmd)
+{
+ int rc, errno_cache;
+ uint8_t nr = _IOC_NR(variant->ioctl_cmd);
+ unsigned long cmds[] = {
+ _IOWR('a', nr, struct uvio_ioctl_cb),
+ _IOWR(UVIO_TYPE_UVC, nr, int),
+ _IO(UVIO_TYPE_UVC, nr),
+ _IOR(UVIO_TYPE_UVC, nr, struct uvio_ioctl_cb),
+ _IOW(UVIO_TYPE_UVC, nr, struct uvio_ioctl_cb),
+ };
+
+ for (size_t i = 0; i < ARRAY_SIZE(cmds); i++) {
+ rc = ioctl(self->uv_fd, cmds[i], &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, ENOTTY);
+ }
+}
+
+struct test_attest_buffer {
+ uint8_t arcb[0x180];
+ uint8_t meas[64];
+ uint8_t add[32];
+};
+
+FIXTURE(attest_fixture) {
+ int uv_fd;
+ struct uvio_ioctl_cb uvio_ioctl;
+ struct uvio_attest uvio_attest;
+ struct test_attest_buffer attest_buffer;
+ __u64 fault_page;
+};
+
+FIXTURE_SETUP(attest_fixture)
+{
+ self->uv_fd = open(UV_PATH, O_ACCMODE);
+
+ self->uvio_ioctl.argument_addr = (__u64)&self->uvio_attest;
+ self->uvio_ioctl.argument_len = sizeof(self->uvio_attest);
+
+ self->uvio_attest.arcb_addr = (__u64)&self->attest_buffer.arcb;
+ self->uvio_attest.arcb_len = sizeof(self->attest_buffer.arcb);
+
+ self->uvio_attest.meas_addr = (__u64)&self->attest_buffer.meas;
+ self->uvio_attest.meas_len = sizeof(self->attest_buffer.meas);
+
+ self->uvio_attest.add_data_addr = (__u64)&self->attest_buffer.add;
+ self->uvio_attest.add_data_len = sizeof(self->attest_buffer.add);
+ self->fault_page =
+ (__u64)mmap(NULL, (size_t)getpagesize(), PROT_NONE, MAP_ANONYMOUS, -1, 0);
+}
+
+FIXTURE_TEARDOWN(attest_fixture)
+{
+ if (self->uv_fd)
+ close(self->uv_fd);
+ munmap((void *)self->fault_page, (size_t)getpagesize());
+}
+
+static void att_inval_sizes_test(uint32_t *size, uint32_t max_size, bool test_zero,
+ struct __test_metadata *_metadata,
+ FIXTURE_DATA(attest_fixture) *self)
+{
+ int rc, errno_cache;
+ uint32_t tmp = *size;
+
+ if (test_zero) {
+ *size = 0;
+ rc = ioctl(self->uv_fd, UVIO_IOCTL_ATT, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+ }
+ *size = max_size + 1;
+ rc = ioctl(self->uv_fd, UVIO_IOCTL_ATT, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+ *size = tmp;
+}
+
+/*
+ * Test to verify that attestation IOCTLs with invalid values in the UVIO
+ * attestation control block are rejected.
+ */
+TEST_F(attest_fixture, att_inval_request)
+{
+ int rc, errno_cache;
+
+ att_inval_sizes_test(&self->uvio_attest.add_data_len, UVIO_ATT_ADDITIONAL_MAX_LEN,
+ false, _metadata, self);
+ att_inval_sizes_test(&self->uvio_attest.meas_len, UVIO_ATT_MEASUREMENT_MAX_LEN,
+ true, _metadata, self);
+ att_inval_sizes_test(&self->uvio_attest.arcb_len, UVIO_ATT_ARCB_MAX_LEN,
+ true, _metadata, self);
+
+ self->uvio_attest.reserved136 = (uint16_t)-1;
+ rc = ioctl(self->uv_fd, UVIO_IOCTL_ATT, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EINVAL);
+
+ memset(&self->uvio_attest, 0x11, sizeof(self->uvio_attest));
+ rc = ioctl(self->uv_fd, UVIO_IOCTL_ATT, &self->uvio_ioctl);
+ ASSERT_EQ(rc, -1);
+}
+
+static void att_inval_addr_test(__u64 *addr, struct __test_metadata *_metadata,
+ FIXTURE_DATA(attest_fixture) *self)
+{
+ int rc, errno_cache;
+ __u64 tmp = *addr;
+
+ *addr = 0;
+ rc = ioctl(self->uv_fd, UVIO_IOCTL_ATT, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EFAULT);
+ *addr = self->fault_page;
+ rc = ioctl(self->uv_fd, UVIO_IOCTL_ATT, &self->uvio_ioctl);
+ errno_cache = errno;
+ ASSERT_EQ(rc, -1);
+ ASSERT_EQ(errno_cache, EFAULT);
+ *addr = tmp;
+}
+
+TEST_F(attest_fixture, att_inval_addr)
+{
+ att_inval_addr_test(&self->uvio_attest.arcb_addr, _metadata, self);
+ att_inval_addr_test(&self->uvio_attest.add_data_addr, _metadata, self);
+ att_inval_addr_test(&self->uvio_attest.meas_addr, _metadata, self);
+}
+
+static void __attribute__((constructor)) __constructor_order_last(void)
+{
+ if (!__constructor_order)
+ __constructor_order = _CONSTRUCTOR_ORDER_BACKWARD;
+}
+
+int main(int argc, char **argv)
+{
+ int fd = open(UV_PATH, O_ACCMODE);
+
+ if (fd < 0)
+ ksft_exit_skip("No uv-device or cannot access " UV_PATH "\n"
+ "Enable CONFIG_S390_UV_UAPI and check the access rights on "
+ UV_PATH ".\n");
+ close(fd);
+ return test_harness_run(argc, argv);
+}
--
2.30.2


2022-05-23 08:02:01

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH v4 2/2] selftests: drivers/s390x: Add uvdevice tests

On 5/10/22 7:47 PM, Steffen Eiden wrote:
> Adds some selftests to test ioctl error paths of the uv-uapi.
> The Kconfig S390_UV_UAPI must be selected and the Ultravisor facility
> must be available. The test can be executed by non-root, however, the
> uvdevice special file /dev/uv must be accessible for reading and
> writing which may imply root privileges.
>
> ./test-uv-device
> TAP version 13
> 1..6
> # Starting 6 tests from 3 test cases.
> # RUN uvio_fixture.att.fault_ioctl_arg ...
> # OK uvio_fixture.att.fault_ioctl_arg
> ok 1 uvio_fixture.att.fault_ioctl_arg
> # RUN uvio_fixture.att.fault_uvio_arg ...
> # OK uvio_fixture.att.fault_uvio_arg
> ok 2 uvio_fixture.att.fault_uvio_arg
> # RUN uvio_fixture.att.inval_ioctl_cb ...
> # OK uvio_fixture.att.inval_ioctl_cb
> ok 3 uvio_fixture.att.inval_ioctl_cb
> # RUN uvio_fixture.att.inval_ioctl_cmd ...
> # OK uvio_fixture.att.inval_ioctl_cmd
> ok 4 uvio_fixture.att.inval_ioctl_cmd
> # RUN attest_fixture.att_inval_request ...
> # OK attest_fixture.att_inval_request
> ok 5 attest_fixture.att_inval_request
> # RUN attest_fixture.att_inval_addr ...
> # OK attest_fixture.att_inval_addr
> ok 6 attest_fixture.att_inval_addr
> # PASSED: 6 / 6 tests passed.
> # Totals: pass:6 fail:0 xfail:0 xpass:0 skip:0 error:0
Maybe we shouldn't add the result like this in the commit message. The
test order may change and it may become invalid soon. Just put it after
the commit message.

> Signed-off-by: Steffen Eiden <[email protected]>
> Acked-by: Janosch Frank <[email protected]>
> ---
> MAINTAINERS | 1 +
> tools/testing/selftests/Makefile | 1 +
> tools/testing/selftests/drivers/.gitignore | 1 +
> .../selftests/drivers/s390x/uvdevice/Makefile | 22 ++
> .../selftests/drivers/s390x/uvdevice/config | 1 +
> .../drivers/s390x/uvdevice/test_uvdevice.c | 276 ++++++++++++++++++
> 6 files changed, 302 insertions(+)
> create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/Makefile
> create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/config
> create mode 100644 tools/testing/selftests/drivers/s390x/uvdevice/test_uvdevice.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b42ab4a35e18..46a9b1467380 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10786,6 +10786,7 @@ F: arch/s390/kernel/uv.c
> F: arch/s390/kvm/
> F: arch/s390/mm/gmap.c
> F: drivers/s390/char/uvdevice.c
> +F: tools/testing/selftests/drivers/s390x/uvdevice/
> F: tools/testing/selftests/kvm/*/s390x/
> F: tools/testing/selftests/kvm/s390x/
>
> diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
> index 2319ec87f53d..d6b307371ef7 100644
> --- a/tools/testing/selftests/Makefile
> +++ b/tools/testing/selftests/Makefile
> @@ -10,6 +10,7 @@ TARGETS += core
> TARGETS += cpufreq
> TARGETS += cpu-hotplug
> TARGETS += drivers/dma-buf
> +TARGETS += drivers/s390x/uvdevice
> TARGETS += efivarfs
> TARGETS += exec
> TARGETS += filesystems
> diff --git a/tools/testing/selftests/drivers/.gitignore b/tools/testing/selftests/drivers/.gitignore
> index ca74f2e1c719..09e23b5afa96 100644
> --- a/tools/testing/selftests/drivers/.gitignore
> +++ b/tools/testing/selftests/drivers/.gitignore
> @@ -1,2 +1,3 @@
> # SPDX-License-Identifier: GPL-2.0-only
> /dma-buf/udmabuf
> +/s390x/uvdevice/test_uvdevice
> diff --git a/tools/testing/selftests/drivers/s390x/uvdevice/Makefile b/tools/testing/selftests/drivers/s390x/uvdevice/Makefile
> new file mode 100644
> index 000000000000..5e701d2708d4
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/s390x/uvdevice/Makefile
> @@ -0,0 +1,22 @@
> +include ../../../../../build/Build.include
> +
> +UNAME_M := $(shell uname -m)
> +
> +ifneq ($(UNAME_M),s390x)
> +nothing:
> +.PHONY: all clean run_tests install
> +.SILENT:
> +else
> +
> +TEST_GEN_PROGS := test_uvdevice
> +
> +top_srcdir ?= ../../../../../..
> +KSFT_KHDR_INSTALL := 1
> +khdr_dir = $(top_srcdir)/usr/include
This doesn't work in different build cases. Please use $(KHDR_INCLUDES)
instead.

> +LINUX_TOOL_ARCH_INCLUDE = $(top_srcdir)/tools/arch/$(ARCH)/include
Which header files do you need from here? I'm not sure what is the
purpose of the header files in $(top_srcdir)/tools/arch and where they
are used.

> +
> +CFLAGS += -Wall -Werror -static -I$(khdr_dir) -I$(LINUX_TOOL_ARCH_INCLUDE)
> +
> +include ../../../lib.mk
> +
> +endif
--
Muhammad Usama Anjum