When debugging a paravirtualized guest firmware, it results very useful to dump the fw_cfg table. Add a HMP command which displays the most useful fields. We display each fw_cfg item data in hexadecimal (only the first 8 bytes):
$ (echo info fw_cfg; echo q) | qemu-system-x86_64 -S -monitor stdio (qemu) info fw_cfg Selector Well-Known Key Pathname ArchSpec Perm Size Order Hex Data 0x0000 signature RO 4 51454d55 0x0001 id RO 4 03000000 0x0002 uuid RO 16 0000000000000000.. 0x0003 ram_size RO 8 0000000800000000 0x0004 nographic RO 2 0000 0x0005 nb_cpus RO 2 0100 0x000d numa RO 16 0000000000000000.. 0x000e boot_menu RO 2 0000 0x000f max_cpus RO 2 0100 0x0019 file_dir RO 2052 0000000b00000000.. 0x0021 file: etc/acpi/rsdp RO 20 160 5253442050545220.. 0x0022 file: etc/acpi/tables RO 131072 130 4641435340000000.. 0x0023 file: etc/boot-fail-wait RO 4 15 ffffffff 0x0024 file: etc/e820 RO 20 40 0000000000000000.. 0x0025 file: etc/smbios/smbios-anchor RO 31 30 5f534d5f001f0208.. 0x0026 file: etc/smbios/smbios-tables RO 321 20 011b000101020300.. 0x0027 file: etc/system-states RO 6 90 800000818280 0x0028 file: etc/table-loader RO 4096 140 010000006574632f.. 0x002a file: genroms/kvmvapic.bin RO 9216 55 55aa12060e0731c0.. 0x0002 irq0_override * RO 4 01000000 0x0003 e820_tables * RO 324 0000000000000000.. 0x0004 hpet * RO 121 0101a286800000d0.. (qemu) q $ (echo info fw_cfg; echo q) | qemu-system-mips -S -monitor stdio (qemu) info fw_cfg This machine does not use fw_cfg (qemu) q $ (echo info fw_cfg; echo q) | qemu-system-ppc -S -monitor stdio (qemu) info fw_cfg Selector Well-Known Key Pathname ArchSpec Perm Size Order Hex Data 0x0000 signature RO 4 51454d55 0x0001 id RO 4 01000000 0x0002 uuid RO 16 0000000000000000.. 0x0003 ram_size RO 8 0000000800000000 0x0004 nographic RO 2 0000 0x0005 nb_cpus RO 2 0100 0x0006 machine_id RO 2 0200 0x0007 kernel_addr RO 4 00000000 0x0008 kernel_size RO 4 00000000 0x0009 kernel_cmdline RO 4 00000000 0x000a initrd_addr RO 4 00000000 0x000b initdr_size RO 4 00000000 0x000c boot_device RO 2 6300 0x000e boot_menu RO 2 0000 0x000f max_cpus RO 2 0100 0x0019 file_dir RO 2052 0000000200000000.. 0x0021 file: etc/boot-fail-wait RO 4 15 ffffffff 0x0000 width * RO 2 2003 0x0001 height * RO 2 5802 0x0002 depth * RO 2 2000 0x0003 tbfreq * RO 4 c04bfd00 0x0004 clockfreq * RO 4 80d6da0f 0x0005 is_kvm * RO 4 00000000 0x0009 busfreq * RO 4 8014ef03 (qemu) q Signed-off-by: Philippe Mathieu-Daudé <phi...@redhat.com> --- v2: Check fw_cfg != NULL (Michael) Rename keys, display data in hexa (Laszlo) --- hmp-commands-info.hx | 17 ++++++++++ hw/nvram/fw_cfg.c | 71 ++++++++++++++++++++++++++++++++++++++- include/hw/nvram/fw_cfg.h | 2 ++ 3 files changed, 89 insertions(+), 1 deletion(-) diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx index cbee8b944d..2c9538c8da 100644 --- a/hmp-commands-info.hx +++ b/hmp-commands-info.hx @@ -916,6 +916,23 @@ STEXI @item info sev @findex info sev Show SEV information. +ETEXI + + { + .name = "fw_cfg", + .args_type = "", + .params = "", + .help = "Display the table firmware configuration entries " + "registered by a paravirtualized machine. Helpful " + "when debugging guest firmwares.", + .cmd = hmp_info_fw_cfg, + }, + +STEXI +@item info fw_cfg +@findex info fw_cfg +Display the table firmware configuration entries registered by a paravirtualized +machine. This information is useful when debugging guest firmwares. ETEXI STEXI diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c index 2a8d69ba07..4c82dcc125 100644 --- a/hw/nvram/fw_cfg.c +++ b/hw/nvram/fw_cfg.c @@ -35,6 +35,7 @@ #include "qemu/config-file.h" #include "qemu/cutils.h" #include "qapi/error.h" +#include "monitor/monitor.h" #include "qapi/qapi-commands-misc.h" #define FW_CFG_FILE_SLOTS_DFLT 0x20 @@ -1273,7 +1274,18 @@ static FirmwareConfigurationItem *create_qmp_fw_cfg_item(FWCfgState *s, return item; } -FirmwareConfigurationItemList *qmp_query_fw_cfg_items(Error **errp) +/** + * query_fw_cfg_items: + * + * @use_hexdump: Whether to populate the @data field with the hexadecimal + * representation of the item data. + * @errp: Pointer to a NULL initialized error object. + * + * Returns: A list of @FirmwareConfigurationItem, reverse sorted by the + * item selector key. + */ +static FirmwareConfigurationItemList *query_fw_cfg_items(bool use_hexdump, + Error **errp) { FirmwareConfigurationItemList *item_list = NULL; uint32_t max_entries; @@ -1294,6 +1306,9 @@ FirmwareConfigurationItemList *qmp_query_fw_cfg_items(Error **errp) if (!e->len) { continue; } + if (use_hexdump) { + qmp_hex_length = MIN(e->len, 8); + } info = g_malloc0(sizeof(*info)); info->value = create_qmp_fw_cfg_item(s, e, arch, key, @@ -1305,3 +1320,57 @@ FirmwareConfigurationItemList *qmp_query_fw_cfg_items(Error **errp) return item_list; } + +FirmwareConfigurationItemList *qmp_query_fw_cfg_items(Error **errp) +{ + return query_fw_cfg_items(false, errp); +} + +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict) +{ + FirmwareConfigurationItemList *item_list, *method; + Error *err = NULL; + + item_list = query_fw_cfg_items(true, &err); + if (!item_list) { + monitor_printf(mon, "This machine does not use fw_cfg\n"); + return; + } + if (err) { + monitor_printf(mon, "Could not query fw_cfg entries: %s\n", + error_get_pretty(err)); + error_free(err); + return; + } + + monitor_printf(mon, "Selector Well-Known Key Pathname" + " ArchSpec Perm Size Order Hex Data\n"); + for (method = item_list; method; method = method->next) { + if (method->value->has_path) { + monitor_printf(mon, + " 0x%04x file: %-28s %2s %7" PRId64 + " %3" PRId64 " %-16s%s\n", + method->value->key, + method->value->path, + method->value->writeable ? "RW" : "RO", + method->value->size, + method->value->order, + method->value->data, + method->value->size > 8 ? ".." : ""); + } else { + monitor_printf(mon, + " 0x%04x %-30s %c %2s %7" PRId64 + " %-16s%s\n", + method->value->key, + method->value->has_keyname + ? method->value->keyname : "", + method->value->architecture_specific ? '*' : ' ', + method->value->writeable ? "RW" : "RO", + method->value->size, + method->value->data, + method->value->size > 8 ? ".." : ""); + } + } + + qapi_free_FirmwareConfigurationItemList(item_list); +} diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h index 83a0540b6c..5ac9adfe1f 100644 --- a/include/hw/nvram/fw_cfg.h +++ b/include/hw/nvram/fw_cfg.h @@ -243,4 +243,6 @@ bool fw_cfg_dma_enabled(void *opaque); */ const char *fw_cfg_arch_key_name(uint16_t key); +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict); + #endif -- 2.20.1