tests/qtest/vmcoreinfo: add a unit test to exercize basic vmcoreinfo function

A new qtest is written that exercizes the fw-cfg DMA based read and write ops
to write values into vmcoreinfo fw-cfg file and read them back and verify that
they are the same.

Signed-off-by: Ani Sinha <anisinha@redhat.com>
Message-ID: <20250120043847.954881-4-anisinha@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

MAINTAINERS

@@ -3019,6 +3019,7 @@ F: include/system/device_tree.h
 Dump
 S: Supported
 M: Marc-André Lureau <marcandre.lureau@redhat.com>
+R: Ani Sinha <anisinha@redhat.com>
 F: dump/
 F: hw/misc/vmcoreinfo.c
 F: include/hw/misc/vmcoreinfo.h
@@ -3029,6 +3030,7 @@ F: qapi/dump.json
 F: scripts/dump-guest-memory.py
 F: stubs/dump.c
 F: docs/specs/vmcoreinfo.rst
+F: tests/qtest/vmcoreinfo-test.c
 
 Error reporting
 M: Markus Armbruster <armbru@redhat.com>

tests/qtest/meson.build

@@ -57,6 +57,7 @@ qtests_i386 = \
   (config_all_devices.has_key('CONFIG_AHCI_ICH9') ? ['tco-test'] : []) +                    \
   (config_all_devices.has_key('CONFIG_FDC_ISA') ? ['fdc-test'] : []) +                      \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['fw_cfg-test'] : []) +                    \
+  (config_all_devices.has_key('CONFIG_FW_CFG_DMA') ? ['vmcoreinfo-test'] : []) +            \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['i440fx-test'] : []) +                    \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['ide-test'] : []) +                       \
   (config_all_devices.has_key('CONFIG_I440FX') ? ['numa-test'] : []) +                      \

tests/qtest/vmcoreinfo-test.c

@@ -0,0 +1,90 @@
+/*
+ * qtest vmcoreinfo test case
+ *
+ * Copyright Red Hat. 2025.
+ *
+ * Authors:
+ *  Ani Sinha   <anisinha@redhat.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/units.h"
+#include "libqos/libqos-pc.h"
+#include "libqtest.h"
+#include "standard-headers/linux/qemu_fw_cfg.h"
+#include "libqos/fw_cfg.h"
+#include "qemu/bswap.h"
+#include "hw/misc/vmcoreinfo.h"
+
+static void test_vmcoreinfo_write_basic(void)
+{
+    QFWCFG *fw_cfg;
+    QOSState *qs;
+    FWCfgVMCoreInfo info;
+    size_t filesize;
+    uint16_t guest_format;
+    uint16_t host_format;
+    uint32_t size;
+    uint64_t paddr;
+
+    qs = qtest_pc_boot("-device vmcoreinfo");
+    fw_cfg = pc_fw_cfg_init(qs->qts);
+
+    memset(&info, 0 , sizeof(info));
+    /* read vmcoreinfo and read back the host format */
+    filesize = qfw_cfg_read_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
+                                &info, sizeof(info));
+    g_assert_cmpint(filesize, ==, sizeof(info));
+
+    host_format = le16_to_cpu(info.host_format);
+    g_assert_cmpint(host_format, ==, FW_CFG_VMCOREINFO_FORMAT_ELF);
+
+    memset(&info, 0 , sizeof(info));
+    info.guest_format = cpu_to_le16(FW_CFG_VMCOREINFO_FORMAT_ELF);
+    info.size = cpu_to_le32(1 * MiB);
+    info.paddr = cpu_to_le64(0xffffff00);
+    info.host_format = cpu_to_le16(host_format);
+
+    /* write the values to the host */
+    filesize = qfw_cfg_write_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
+                                  &info, sizeof(info));
+    g_assert_cmpint(filesize, ==, sizeof(info));
+
+    memset(&info, 0 , sizeof(info));
+
+    /* now read back the values we wrote and compare that they are the same */
+    filesize = qfw_cfg_read_file(fw_cfg, qs, FW_CFG_VMCOREINFO_FILENAME,
+                                &info, sizeof(info));
+    g_assert_cmpint(filesize, ==, sizeof(info));
+
+    size = le32_to_cpu(info.size);
+    paddr = le64_to_cpu(info.paddr);
+    guest_format = le16_to_cpu(info.guest_format);
+
+    g_assert_cmpint(size, ==, 1 * MiB);
+    g_assert_cmpint(paddr, ==, 0xffffff00);
+    g_assert_cmpint(guest_format, ==, FW_CFG_VMCOREINFO_FORMAT_ELF);
+
+    pc_fw_cfg_uninit(fw_cfg);
+    qtest_shutdown(qs);
+}
+
+int main(int argc, char **argv)
+{
+    const char *arch = qtest_get_arch();
+
+    g_test_init(&argc, &argv, NULL);
+
+    if (strcmp(arch, "i386") && strcmp(arch, "x86_64")) {
+        /* skip for non-x86 */
+        exit(EXIT_SUCCESS);
+    }
+
+    qtest_add_func("vmcoreinfo/basic-write",
+                   test_vmcoreinfo_write_basic);
+
+    return g_test_run();
+}