[5/6] hw/nvram/fw_cfg: Add HMP 'info fw_cfg' command
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Message ID 20181207170400.5129-6-philmd@redhat.com
State New
Headers show
Series
  • fw_cfg: add HMP 'info fw_cfg' and add_file_from_host()
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Commit Message

Philippe Mathieu-Daudé Dec. 7, 2018, 5:03 p.m. UTC
$ qemu-system-x86_64 -S -monitor stdio
(qemu) info fw_cfg
        Type    Perm    Size    Specific   Order   Info
   signature      RO       4                       QEMU
          id      RO       4                       0x00000003
        uuid      RO      16                       00000000-0000-0000-0000-000000000000
    ram_size      RO       8                       0x0000000008000000
   nographic      RO       2                       0x0000
     nb_cpus      RO       2                       0x0001
        numa      RO      16
   boot_menu      RO       2                       0x0000
    max_cpus      RO       2                       0x0001
    file_dir      RO    2052
 file (id 1)      RO      36                 160   etc/acpi/rsdp
 file (id 2)      RO  131072                 130   etc/acpi/tables
 file (id 3)      RO       4                  15   etc/boot-fail-wait
 file (id 4)      RO      20                  40   etc/e820
 file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
 file (id 6)      RO     320                  20   etc/smbios/smbios-tables
 file (id 7)      RO       6                  90   etc/system-states
 file (id 8)      RO    4096                 140   etc/table-loader
file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
        uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
    ram_size      RO     324  (arch spec)
   nographic      RO     121  (arch spec)
(qemu)

Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hmp-commands-info.hx      |  14 +++++
 hw/nvram/fw_cfg.c         | 115 ++++++++++++++++++++++++++++++++++++++
 include/hw/nvram/fw_cfg.h |   2 +
 3 files changed, 131 insertions(+)

Comments

Eric Blake Dec. 7, 2018, 5:26 p.m. UTC | #1
On 12/7/18 11:03 AM, Philippe Mathieu-Daudé wrote:
> $ qemu-system-x86_64 -S -monitor stdio
> (qemu) info fw_cfg
>          Type    Perm    Size    Specific   Order   Info
>     signature      RO       4                       QEMU
>            id      RO       4                       0x00000003
>          uuid      RO      16                       00000000-0000-0000-0000-000000000000
>      ram_size      RO       8                       0x0000000008000000
>     nographic      RO       2                       0x0000
>       nb_cpus      RO       2                       0x0001
>          numa      RO      16
>     boot_menu      RO       2                       0x0000
>      max_cpus      RO       2                       0x0001
>      file_dir      RO    2052
>   file (id 1)      RO      36                 160   etc/acpi/rsdp
>   file (id 2)      RO  131072                 130   etc/acpi/tables
>   file (id 3)      RO       4                  15   etc/boot-fail-wait
>   file (id 4)      RO      20                  40   etc/e820
>   file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
>   file (id 6)      RO     320                  20   etc/smbios/smbios-tables
>   file (id 7)      RO       6                  90   etc/system-states
>   file (id 8)      RO    4096                 140   etc/table-loader
> file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
>          uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
>      ram_size      RO     324  (arch spec)
>     nographic      RO     121  (arch spec)
> (qemu)
> 

In general, when adding something to HMP but not QMP, it is worth a 
comment explaining WHY we did not want QMP.  (Here, I think the reason 
is that this is a debugging aid likely to be useful to developers but 
unlikely to be needed by a management app, and matches similar other 
HMP-only info commands, and is therefore not worth the effort of turning 
it into QAPI).
Michael S. Tsirkin Dec. 7, 2018, 5:54 p.m. UTC | #2
On Fri, Dec 07, 2018 at 06:03:59PM +0100, Philippe Mathieu-Daudé wrote:
> $ qemu-system-x86_64 -S -monitor stdio
> (qemu) info fw_cfg
>         Type    Perm    Size    Specific   Order   Info

Can we do better than "Info"?

>    signature      RO       4                       QEMU
>           id      RO       4                       0x00000003
>         uuid      RO      16                       00000000-0000-0000-0000-000000000000
>     ram_size      RO       8                       0x0000000008000000
>    nographic      RO       2                       0x0000
>      nb_cpus      RO       2                       0x0001
>         numa      RO      16
>    boot_menu      RO       2                       0x0000
>     max_cpus      RO       2                       0x0001
>     file_dir      RO    2052
>  file (id 1)      RO      36                 160   etc/acpi/rsdp
>  file (id 2)      RO  131072                 130   etc/acpi/tables
>  file (id 3)      RO       4                  15   etc/boot-fail-wait
>  file (id 4)      RO      20                  40   etc/e820
>  file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
>  file (id 6)      RO     320                  20   etc/smbios/smbios-tables
>  file (id 7)      RO       6                  90   etc/system-states
>  file (id 8)      RO    4096                 140   etc/table-loader
> file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
>         uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
>     ram_size      RO     324  (arch spec)
>    nographic      RO     121  (arch spec)

Weird. Your code has arch_spec.

> (qemu)
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>


Looks helpful but generally IMHO whatever is exposed through hmp
should be in the qmp as well.


> ---
>  hmp-commands-info.hx      |  14 +++++
>  hw/nvram/fw_cfg.c         | 115 ++++++++++++++++++++++++++++++++++++++
>  include/hw/nvram/fw_cfg.h |   2 +
>  3 files changed, 131 insertions(+)
> 
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index cbee8b944d..9e86dceeb4 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -916,6 +916,20 @@ STEXI
>  @item info sev
>  @findex info sev
>  Show SEV information.
> +ETEXI
> +
> +    {
> +        .name       = "fw_cfg",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "Display the table of the fw_cfg entries registered",

I think the help line should be a bit more verbose.
Mention it's a paravirtualized interface, and why
would one want to display it (debugging guest firmware?).


> +        .cmd        = hmp_info_fw_cfg,
> +    },
> +
> +STEXI
> +@item info fw_cfg
> +@findex info fw_cfg
> +Show roms.
>  ETEXI
>  
>  STEXI
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 582653f07e..50525ec1dd 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -36,6 +36,7 @@
>  #include "qemu/config-file.h"
>  #include "qemu/cutils.h"
>  #include "qapi/error.h"
> +#include "monitor/monitor.h"
>  
>  #define FW_CFG_FILE_SLOTS_DFLT 0x20
>  
> @@ -1164,3 +1165,117 @@ static void fw_cfg_register_types(void)
>  }
>  
>  type_init(fw_cfg_register_types)
> +
> +static const char *fw_cfg_wellknown_entries[0x20] = {
> +    [FW_CFG_SIGNATURE] = "signature",
> +    [FW_CFG_ID] = "id",
> +    [FW_CFG_UUID] = "uuid",
> +    [FW_CFG_RAM_SIZE] = "ram_size",
> +    [FW_CFG_NOGRAPHIC] = "nographic",
> +    [FW_CFG_NB_CPUS] = "nb_cpus",
> +    [FW_CFG_MACHINE_ID] = "machine_id",
> +    [FW_CFG_KERNEL_ADDR] = "kernel_addr",
> +    [FW_CFG_KERNEL_SIZE] = "kernel_size",
> +    [FW_CFG_KERNEL_CMDLINE] = "kernel_cmdline",
> +    [FW_CFG_INITRD_ADDR] = "initrd_addr",
> +    [FW_CFG_INITRD_SIZE] = "initdr_size",
> +    [FW_CFG_BOOT_DEVICE] = "boot_device",
> +    [FW_CFG_NUMA] = "numa",
> +    [FW_CFG_BOOT_MENU] = "boot_menu",
> +    [FW_CFG_MAX_CPUS] = "max_cpus",
> +    [FW_CFG_KERNEL_ENTRY] = "kernel_entry",
> +    [FW_CFG_KERNEL_DATA] = "kernel_data",
> +    [FW_CFG_INITRD_DATA] = "initrd_data",
> +    [FW_CFG_CMDLINE_ADDR] = "cmdline_addr",
> +    [FW_CFG_CMDLINE_SIZE] = "cmdline_size",
> +    [FW_CFG_CMDLINE_DATA] = "cmdline_data",
> +    [FW_CFG_SETUP_ADDR] = "setup_addr",
> +    [FW_CFG_SETUP_SIZE] = "setup_size",
> +    [FW_CFG_SETUP_DATA] = "setup_data",
> +    [FW_CFG_FILE_DIR] = "file_dir",
> +};
> +
> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict)
> +{
> +    FWCfgState *s = fw_cfg_find();
> +    int arch, key;

Looks like this will crash on a machine without fw cfg.


> +
> +    monitor_printf(mon, "%12s %5s %7s %9s %6s %-24s\n",
> +                   "Type", "Perm", "Size", "Specific", "Order", "Info");
> +    for (arch = 0; arch < ARRAY_SIZE(s->entries); ++arch) {
> +        for (key = 0; key < fw_cfg_max_entry(s); ++key) {
> +            FWCfgEntry *e = &s->entries[arch][key];
> +            const char *perm = e->allow_write ? "RW" : "RO";
> +            const char *arch_spec = arch ? "arch_spec" : "";
> +            char *type, *info = NULL;
> +
> +            if (!e->len) {
> +                continue;
> +            }
> +            if (key >= FW_CFG_FILE_FIRST) {
> +                int id = key - FW_CFG_FILE_FIRST;
> +                const char *path = s->files->f[id].name;
> +
> +                type = g_strdup_printf("file (id %d)", id);
> +                monitor_printf(mon, "%12s %5s %7d %10s %5d %-24s\n",
> +                               type, perm, e->len, arch_spec,
> +                               get_fw_cfg_order(s, path), path);
> +                g_free(type);
> +                continue;
> +            }
> +            type = g_strdup(fw_cfg_wellknown_entries[key]);
> +            if (!type) {
> +                type = g_strdup_printf("entry_%d", key);
> +            }
> +
> +            switch (key) {
> +            case FW_CFG_SIGNATURE:
> +                info = g_strndup((const gchar *)e->data, e->len);
> +                break;
> +            case FW_CFG_UUID:
> +                info = qemu_uuid_unparse_strdup((const QemuUUID *)e->data);
> +                break;
> +            case FW_CFG_ID:
> +            case FW_CFG_NOGRAPHIC:
> +            case FW_CFG_NB_CPUS:
> +            case FW_CFG_BOOT_MENU:
> +            case FW_CFG_MAX_CPUS:
> +            case FW_CFG_RAM_SIZE:
> +            case FW_CFG_KERNEL_ADDR:
> +            case FW_CFG_KERNEL_SIZE:
> +            case FW_CFG_KERNEL_CMDLINE:
> +            case FW_CFG_KERNEL_ENTRY:
> +            case FW_CFG_KERNEL_DATA:
> +            case FW_CFG_INITRD_ADDR:
> +            case FW_CFG_INITRD_SIZE:
> +            case FW_CFG_INITRD_DATA:
> +            case FW_CFG_CMDLINE_ADDR:
> +            case FW_CFG_CMDLINE_SIZE:
> +            case FW_CFG_CMDLINE_DATA:
> +            case FW_CFG_SETUP_ADDR:
> +            case FW_CFG_SETUP_SIZE:
> +            case FW_CFG_SETUP_DATA:
> +                switch (e->len) {
> +                case 2:
> +                    info = g_strdup_printf("0x%04x", lduw_le_p(e->data));
> +                    break;
> +                case 4:
> +                    info = g_strdup_printf("0x%08x", ldl_le_p(e->data));
> +                    break;
> +                case 8:
> +                    info = g_strdup_printf("0x%016" PRIx64, ldq_le_p(e->data));
> +                    break;
> +                default:
> +                    break;
> +                }
> +                break;
> +            default:
> +                break;
> +            }
> +            monitor_printf(mon, "%12s %5s %7d %10s %5s %-24s\n",
> +                           type, perm, e->len, arch_spec, "", info ? info : "");
> +            g_free(type);
> +            g_free(info);
> +        }
> +    }
> +}
> diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
> index f5a6895a74..28630b2f26 100644
> --- a/include/hw/nvram/fw_cfg.h
> +++ b/include/hw/nvram/fw_cfg.h
> @@ -226,4 +226,6 @@ FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
>  FWCfgState *fw_cfg_find(void);
>  bool fw_cfg_dma_enabled(void *opaque);
>  
> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict);
> +
>  #endif
> -- 
> 2.17.2
Philippe Mathieu-Daudé Dec. 10, 2018, 9:18 a.m. UTC | #3
On 12/7/18 6:54 PM, Michael S. Tsirkin wrote:
> On Fri, Dec 07, 2018 at 06:03:59PM +0100, Philippe Mathieu-Daudé wrote:
>> $ qemu-system-x86_64 -S -monitor stdio
>> (qemu) info fw_cfg
>>         Type    Perm    Size    Specific   Order   Info
> 
> Can we do better than "Info"?

For some entry this is the "content", but for the files this is the
"path". Do you prefer "Content or path"?

> 
>>    signature      RO       4                       QEMU
>>           id      RO       4                       0x00000003
>>         uuid      RO      16                       00000000-0000-0000-0000-000000000000
>>     ram_size      RO       8                       0x0000000008000000
>>    nographic      RO       2                       0x0000
>>      nb_cpus      RO       2                       0x0001
>>         numa      RO      16
>>    boot_menu      RO       2                       0x0000
>>     max_cpus      RO       2                       0x0001
>>     file_dir      RO    2052
>>  file (id 1)      RO      36                 160   etc/acpi/rsdp
>>  file (id 2)      RO  131072                 130   etc/acpi/tables
>>  file (id 3)      RO       4                  15   etc/boot-fail-wait
>>  file (id 4)      RO      20                  40   etc/e820
>>  file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
>>  file (id 6)      RO     320                  20   etc/smbios/smbios-tables
>>  file (id 7)      RO       6                  90   etc/system-states
>>  file (id 8)      RO    4096                 140   etc/table-loader
>> file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
>>         uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
>>     ram_size      RO     324  (arch spec)
>>    nographic      RO     121  (arch spec)
> 
> Weird. Your code has arch_spec.

Hmmm I'll check that.

> 
>> (qemu)
>>
>> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> 
> 
> Looks helpful but generally IMHO whatever is exposed through hmp
> should be in the qmp as well.

OK.

> 
> 
>> ---
>>  hmp-commands-info.hx      |  14 +++++
>>  hw/nvram/fw_cfg.c         | 115 ++++++++++++++++++++++++++++++++++++++
>>  include/hw/nvram/fw_cfg.h |   2 +
>>  3 files changed, 131 insertions(+)
>>
>> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
>> index cbee8b944d..9e86dceeb4 100644
>> --- a/hmp-commands-info.hx
>> +++ b/hmp-commands-info.hx
>> @@ -916,6 +916,20 @@ STEXI
>>  @item info sev
>>  @findex info sev
>>  Show SEV information.
>> +ETEXI
>> +
>> +    {
>> +        .name       = "fw_cfg",
>> +        .args_type  = "",
>> +        .params     = "",
>> +        .help       = "Display the table of the fw_cfg entries registered",
> 
> I think the help line should be a bit more verbose.
> Mention it's a paravirtualized interface, and why
> would one want to display it (debugging guest firmware?).

OK.

> 
> 
>> +        .cmd        = hmp_info_fw_cfg,
>> +    },
>> +
>> +STEXI
>> +@item info fw_cfg
>> +@findex info fw_cfg
>> +Show roms.
>>  ETEXI
>>  
>>  STEXI
>> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
>> index 582653f07e..50525ec1dd 100644
>> --- a/hw/nvram/fw_cfg.c
>> +++ b/hw/nvram/fw_cfg.c
>> @@ -36,6 +36,7 @@
>>  #include "qemu/config-file.h"
>>  #include "qemu/cutils.h"
>>  #include "qapi/error.h"
>> +#include "monitor/monitor.h"
>>  
>>  #define FW_CFG_FILE_SLOTS_DFLT 0x20
>>  
>> @@ -1164,3 +1165,117 @@ static void fw_cfg_register_types(void)
>>  }
>>  
>>  type_init(fw_cfg_register_types)
>> +
>> +static const char *fw_cfg_wellknown_entries[0x20] = {
>> +    [FW_CFG_SIGNATURE] = "signature",
>> +    [FW_CFG_ID] = "id",
>> +    [FW_CFG_UUID] = "uuid",
>> +    [FW_CFG_RAM_SIZE] = "ram_size",
>> +    [FW_CFG_NOGRAPHIC] = "nographic",
>> +    [FW_CFG_NB_CPUS] = "nb_cpus",
>> +    [FW_CFG_MACHINE_ID] = "machine_id",
>> +    [FW_CFG_KERNEL_ADDR] = "kernel_addr",
>> +    [FW_CFG_KERNEL_SIZE] = "kernel_size",
>> +    [FW_CFG_KERNEL_CMDLINE] = "kernel_cmdline",
>> +    [FW_CFG_INITRD_ADDR] = "initrd_addr",
>> +    [FW_CFG_INITRD_SIZE] = "initdr_size",
>> +    [FW_CFG_BOOT_DEVICE] = "boot_device",
>> +    [FW_CFG_NUMA] = "numa",
>> +    [FW_CFG_BOOT_MENU] = "boot_menu",
>> +    [FW_CFG_MAX_CPUS] = "max_cpus",
>> +    [FW_CFG_KERNEL_ENTRY] = "kernel_entry",
>> +    [FW_CFG_KERNEL_DATA] = "kernel_data",
>> +    [FW_CFG_INITRD_DATA] = "initrd_data",
>> +    [FW_CFG_CMDLINE_ADDR] = "cmdline_addr",
>> +    [FW_CFG_CMDLINE_SIZE] = "cmdline_size",
>> +    [FW_CFG_CMDLINE_DATA] = "cmdline_data",
>> +    [FW_CFG_SETUP_ADDR] = "setup_addr",
>> +    [FW_CFG_SETUP_SIZE] = "setup_size",
>> +    [FW_CFG_SETUP_DATA] = "setup_data",
>> +    [FW_CFG_FILE_DIR] = "file_dir",
>> +};
>> +
>> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict)
>> +{
>> +    FWCfgState *s = fw_cfg_find();
>> +    int arch, key;
> 
> Looks like this will crash on a machine without fw cfg.

Oops, good catch :)

> 
> 
>> +
>> +    monitor_printf(mon, "%12s %5s %7s %9s %6s %-24s\n",
>> +                   "Type", "Perm", "Size", "Specific", "Order", "Info");
>> +    for (arch = 0; arch < ARRAY_SIZE(s->entries); ++arch) {
>> +        for (key = 0; key < fw_cfg_max_entry(s); ++key) {
>> +            FWCfgEntry *e = &s->entries[arch][key];
>> +            const char *perm = e->allow_write ? "RW" : "RO";
>> +            const char *arch_spec = arch ? "arch_spec" : "";
>> +            char *type, *info = NULL;
>> +
>> +            if (!e->len) {
>> +                continue;
>> +            }
>> +            if (key >= FW_CFG_FILE_FIRST) {
>> +                int id = key - FW_CFG_FILE_FIRST;
>> +                const char *path = s->files->f[id].name;
>> +
>> +                type = g_strdup_printf("file (id %d)", id);
>> +                monitor_printf(mon, "%12s %5s %7d %10s %5d %-24s\n",
>> +                               type, perm, e->len, arch_spec,
>> +                               get_fw_cfg_order(s, path), path);
>> +                g_free(type);
>> +                continue;
>> +            }
>> +            type = g_strdup(fw_cfg_wellknown_entries[key]);
>> +            if (!type) {
>> +                type = g_strdup_printf("entry_%d", key);
>> +            }
>> +
>> +            switch (key) {
>> +            case FW_CFG_SIGNATURE:
>> +                info = g_strndup((const gchar *)e->data, e->len);
>> +                break;
>> +            case FW_CFG_UUID:
>> +                info = qemu_uuid_unparse_strdup((const QemuUUID *)e->data);
>> +                break;
>> +            case FW_CFG_ID:
>> +            case FW_CFG_NOGRAPHIC:
>> +            case FW_CFG_NB_CPUS:
>> +            case FW_CFG_BOOT_MENU:
>> +            case FW_CFG_MAX_CPUS:
>> +            case FW_CFG_RAM_SIZE:
>> +            case FW_CFG_KERNEL_ADDR:
>> +            case FW_CFG_KERNEL_SIZE:
>> +            case FW_CFG_KERNEL_CMDLINE:
>> +            case FW_CFG_KERNEL_ENTRY:
>> +            case FW_CFG_KERNEL_DATA:
>> +            case FW_CFG_INITRD_ADDR:
>> +            case FW_CFG_INITRD_SIZE:
>> +            case FW_CFG_INITRD_DATA:
>> +            case FW_CFG_CMDLINE_ADDR:
>> +            case FW_CFG_CMDLINE_SIZE:
>> +            case FW_CFG_CMDLINE_DATA:
>> +            case FW_CFG_SETUP_ADDR:
>> +            case FW_CFG_SETUP_SIZE:
>> +            case FW_CFG_SETUP_DATA:
>> +                switch (e->len) {
>> +                case 2:
>> +                    info = g_strdup_printf("0x%04x", lduw_le_p(e->data));
>> +                    break;
>> +                case 4:
>> +                    info = g_strdup_printf("0x%08x", ldl_le_p(e->data));
>> +                    break;
>> +                case 8:
>> +                    info = g_strdup_printf("0x%016" PRIx64, ldq_le_p(e->data));
>> +                    break;
>> +                default:
>> +                    break;
>> +                }
>> +                break;
>> +            default:
>> +                break;
>> +            }
>> +            monitor_printf(mon, "%12s %5s %7d %10s %5s %-24s\n",
>> +                           type, perm, e->len, arch_spec, "", info ? info : "");
>> +            g_free(type);
>> +            g_free(info);
>> +        }
>> +    }
>> +}
>> diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
>> index f5a6895a74..28630b2f26 100644
>> --- a/include/hw/nvram/fw_cfg.h
>> +++ b/include/hw/nvram/fw_cfg.h
>> @@ -226,4 +226,6 @@ FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
>>  FWCfgState *fw_cfg_find(void);
>>  bool fw_cfg_dma_enabled(void *opaque);
>>  
>> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict);
>> +
>>  #endif
>> -- 
>> 2.17.2
Dr. David Alan Gilbert Dec. 10, 2018, 11:42 a.m. UTC | #4
* Philippe Mathieu-Daudé (philmd@redhat.com) wrote:
> $ qemu-system-x86_64 -S -monitor stdio
> (qemu) info fw_cfg
>         Type    Perm    Size    Specific   Order   Info
>    signature      RO       4                       QEMU
>           id      RO       4                       0x00000003
>         uuid      RO      16                       00000000-0000-0000-0000-000000000000
>     ram_size      RO       8                       0x0000000008000000
>    nographic      RO       2                       0x0000
>      nb_cpus      RO       2                       0x0001
>         numa      RO      16
>    boot_menu      RO       2                       0x0000
>     max_cpus      RO       2                       0x0001
>     file_dir      RO    2052
>  file (id 1)      RO      36                 160   etc/acpi/rsdp
>  file (id 2)      RO  131072                 130   etc/acpi/tables
>  file (id 3)      RO       4                  15   etc/boot-fail-wait
>  file (id 4)      RO      20                  40   etc/e820
>  file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
>  file (id 6)      RO     320                  20   etc/smbios/smbios-tables
>  file (id 7)      RO       6                  90   etc/system-states
>  file (id 8)      RO    4096                 140   etc/table-loader
> file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
>         uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
>     ram_size      RO     324  (arch spec)
>    nographic      RO     121  (arch spec)
> (qemu)
> 
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hmp-commands-info.hx      |  14 +++++
>  hw/nvram/fw_cfg.c         | 115 ++++++++++++++++++++++++++++++++++++++
>  include/hw/nvram/fw_cfg.h |   2 +
>  3 files changed, 131 insertions(+)
> 
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index cbee8b944d..9e86dceeb4 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -916,6 +916,20 @@ STEXI
>  @item info sev
>  @findex info sev
>  Show SEV information.
> +ETEXI
> +
> +    {
> +        .name       = "fw_cfg",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "Display the table of the fw_cfg entries registered",
> +        .cmd        = hmp_info_fw_cfg,
> +    },
> +
> +STEXI
> +@item info fw_cfg
> +@findex info fw_cfg
> +Show roms.
>  ETEXI
>  
>  STEXI
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 582653f07e..50525ec1dd 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -36,6 +36,7 @@
>  #include "qemu/config-file.h"
>  #include "qemu/cutils.h"
>  #include "qapi/error.h"
> +#include "monitor/monitor.h"
>  
>  #define FW_CFG_FILE_SLOTS_DFLT 0x20
>  
> @@ -1164,3 +1165,117 @@ static void fw_cfg_register_types(void)
>  }
>  
>  type_init(fw_cfg_register_types)
> +
> +static const char *fw_cfg_wellknown_entries[0x20] = {

That magic 0x20 is a shame; we should probably have a #define
for that max, or perhaps it can just be removed.

> +    [FW_CFG_SIGNATURE] = "signature",
> +    [FW_CFG_ID] = "id",
> +    [FW_CFG_UUID] = "uuid",
> +    [FW_CFG_RAM_SIZE] = "ram_size",
> +    [FW_CFG_NOGRAPHIC] = "nographic",
> +    [FW_CFG_NB_CPUS] = "nb_cpus",
> +    [FW_CFG_MACHINE_ID] = "machine_id",
> +    [FW_CFG_KERNEL_ADDR] = "kernel_addr",
> +    [FW_CFG_KERNEL_SIZE] = "kernel_size",
> +    [FW_CFG_KERNEL_CMDLINE] = "kernel_cmdline",
> +    [FW_CFG_INITRD_ADDR] = "initrd_addr",
> +    [FW_CFG_INITRD_SIZE] = "initdr_size",
> +    [FW_CFG_BOOT_DEVICE] = "boot_device",
> +    [FW_CFG_NUMA] = "numa",
> +    [FW_CFG_BOOT_MENU] = "boot_menu",
> +    [FW_CFG_MAX_CPUS] = "max_cpus",
> +    [FW_CFG_KERNEL_ENTRY] = "kernel_entry",
> +    [FW_CFG_KERNEL_DATA] = "kernel_data",
> +    [FW_CFG_INITRD_DATA] = "initrd_data",
> +    [FW_CFG_CMDLINE_ADDR] = "cmdline_addr",
> +    [FW_CFG_CMDLINE_SIZE] = "cmdline_size",
> +    [FW_CFG_CMDLINE_DATA] = "cmdline_data",
> +    [FW_CFG_SETUP_ADDR] = "setup_addr",
> +    [FW_CFG_SETUP_SIZE] = "setup_size",
> +    [FW_CFG_SETUP_DATA] = "setup_data",
> +    [FW_CFG_FILE_DIR] = "file_dir",
> +};
> +
> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict)
> +{
> +    FWCfgState *s = fw_cfg_find();
> +    int arch, key;
> +
> +    monitor_printf(mon, "%12s %5s %7s %9s %6s %-24s\n",
> +                   "Type", "Perm", "Size", "Specific", "Order", "Info");
> +    for (arch = 0; arch < ARRAY_SIZE(s->entries); ++arch) {
> +        for (key = 0; key < fw_cfg_max_entry(s); ++key) {
> +            FWCfgEntry *e = &s->entries[arch][key];
> +            const char *perm = e->allow_write ? "RW" : "RO";
> +            const char *arch_spec = arch ? "arch_spec" : "";
> +            char *type, *info = NULL;
> +
> +            if (!e->len) {
> +                continue;
> +            }
> +            if (key >= FW_CFG_FILE_FIRST) {
> +                int id = key - FW_CFG_FILE_FIRST;
> +                const char *path = s->files->f[id].name;
> +
> +                type = g_strdup_printf("file (id %d)", id);
> +                monitor_printf(mon, "%12s %5s %7d %10s %5d %-24s\n",
> +                               type, perm, e->len, arch_spec,
> +                               get_fw_cfg_order(s, path), path);
> +                g_free(type);
> +                continue;
> +            }
> +            type = g_strdup(fw_cfg_wellknown_entries[key]);
> +            if (!type) {
> +                type = g_strdup_printf("entry_%d", key);
> +            }
> +
> +            switch (key) {
> +            case FW_CFG_SIGNATURE:
> +                info = g_strndup((const gchar *)e->data, e->len);
> +                break;
> +            case FW_CFG_UUID:
> +                info = qemu_uuid_unparse_strdup((const QemuUUID *)e->data);
> +                break;

It seems odd to encode the type of each entry in this switch;  I guess
it's OK if no one else needs it, else perhaps there should be a type
array.

Other than that, it's fine from the HMP side, but I agree it should
either have a QMP equivalent (in which case the structure is a bit
different) or a good justification of if it's really debug only.

Dave

> +            case FW_CFG_ID:
> +            case FW_CFG_NOGRAPHIC:
> +            case FW_CFG_NB_CPUS:
> +            case FW_CFG_BOOT_MENU:
> +            case FW_CFG_MAX_CPUS:
> +            case FW_CFG_RAM_SIZE:
> +            case FW_CFG_KERNEL_ADDR:
> +            case FW_CFG_KERNEL_SIZE:
> +            case FW_CFG_KERNEL_CMDLINE:
> +            case FW_CFG_KERNEL_ENTRY:
> +            case FW_CFG_KERNEL_DATA:
> +            case FW_CFG_INITRD_ADDR:
> +            case FW_CFG_INITRD_SIZE:
> +            case FW_CFG_INITRD_DATA:
> +            case FW_CFG_CMDLINE_ADDR:
> +            case FW_CFG_CMDLINE_SIZE:
> +            case FW_CFG_CMDLINE_DATA:
> +            case FW_CFG_SETUP_ADDR:
> +            case FW_CFG_SETUP_SIZE:
> +            case FW_CFG_SETUP_DATA:
> +                switch (e->len) {
> +                case 2:
> +                    info = g_strdup_printf("0x%04x", lduw_le_p(e->data));
> +                    break;
> +                case 4:
> +                    info = g_strdup_printf("0x%08x", ldl_le_p(e->data));
> +                    break;
> +                case 8:
> +                    info = g_strdup_printf("0x%016" PRIx64, ldq_le_p(e->data));
> +                    break;
> +                default:
> +                    break;
> +                }
> +                break;
> +            default:
> +                break;
> +            }
> +            monitor_printf(mon, "%12s %5s %7d %10s %5s %-24s\n",
> +                           type, perm, e->len, arch_spec, "", info ? info : "");
> +            g_free(type);
> +            g_free(info);
> +        }
> +    }
> +}
> diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
> index f5a6895a74..28630b2f26 100644
> --- a/include/hw/nvram/fw_cfg.h
> +++ b/include/hw/nvram/fw_cfg.h
> @@ -226,4 +226,6 @@ FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
>  FWCfgState *fw_cfg_find(void);
>  bool fw_cfg_dma_enabled(void *opaque);
>  
> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict);
> +
>  #endif
> -- 
> 2.17.2
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
Laszlo Ersek Dec. 10, 2018, 4:49 p.m. UTC | #5
I can only muster some random thoughts for this one, presently:

On 12/07/18 18:03, Philippe Mathieu-Daudé wrote:
> $ qemu-system-x86_64 -S -monitor stdio
> (qemu) info fw_cfg
>         Type    Perm    Size    Specific   Order   Info
>    signature      RO       4                       QEMU
>           id      RO       4                       0x00000003
>         uuid      RO      16                       00000000-0000-0000-0000-000000000000
>     ram_size      RO       8                       0x0000000008000000
>    nographic      RO       2                       0x0000
>      nb_cpus      RO       2                       0x0001
>         numa      RO      16
>    boot_menu      RO       2                       0x0000
>     max_cpus      RO       2                       0x0001
>     file_dir      RO    2052
>  file (id 1)      RO      36                 160   etc/acpi/rsdp
>  file (id 2)      RO  131072                 130   etc/acpi/tables
>  file (id 3)      RO       4                  15   etc/boot-fail-wait
>  file (id 4)      RO      20                  40   etc/e820
>  file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
>  file (id 6)      RO     320                  20   etc/smbios/smbios-tables
>  file (id 7)      RO       6                  90   etc/system-states
>  file (id 8)      RO    4096                 140   etc/table-loader
> file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
>         uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
>     ram_size      RO     324  (arch spec)
>    nographic      RO     121  (arch spec)
> (qemu)
>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> ---
>  hmp-commands-info.hx      |  14 +++++
>  hw/nvram/fw_cfg.c         | 115 ++++++++++++++++++++++++++++++++++++++
>  include/hw/nvram/fw_cfg.h |   2 +
>  3 files changed, 131 insertions(+)
>
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index cbee8b944d..9e86dceeb4 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -916,6 +916,20 @@ STEXI
>  @item info sev
>  @findex info sev
>  Show SEV information.
> +ETEXI
> +
> +    {
> +        .name       = "fw_cfg",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "Display the table of the fw_cfg entries registered",
> +        .cmd        = hmp_info_fw_cfg,
> +    },
> +
> +STEXI
> +@item info fw_cfg
> +@findex info fw_cfg
> +Show roms.
>  ETEXI
>
>  STEXI
> diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
> index 582653f07e..50525ec1dd 100644
> --- a/hw/nvram/fw_cfg.c
> +++ b/hw/nvram/fw_cfg.c
> @@ -36,6 +36,7 @@
>  #include "qemu/config-file.h"
>  #include "qemu/cutils.h"
>  #include "qapi/error.h"
> +#include "monitor/monitor.h"
>
>  #define FW_CFG_FILE_SLOTS_DFLT 0x20
>
> @@ -1164,3 +1165,117 @@ static void fw_cfg_register_types(void)
>  }
>
>  type_init(fw_cfg_register_types)
> +
> +static const char *fw_cfg_wellknown_entries[0x20] = {

(1) Using 0x20 is not wrong here (it is a well-known magic constant),
but we should refer to it by name: please refer to FW_CFG_FILE_FIRST.
(See "include/standard-headers/linux/qemu_fw_cfg.h")

> +    [FW_CFG_SIGNATURE] = "signature",
> +    [FW_CFG_ID] = "id",
> +    [FW_CFG_UUID] = "uuid",
> +    [FW_CFG_RAM_SIZE] = "ram_size",
> +    [FW_CFG_NOGRAPHIC] = "nographic",
> +    [FW_CFG_NB_CPUS] = "nb_cpus",
> +    [FW_CFG_MACHINE_ID] = "machine_id",
> +    [FW_CFG_KERNEL_ADDR] = "kernel_addr",
> +    [FW_CFG_KERNEL_SIZE] = "kernel_size",
> +    [FW_CFG_KERNEL_CMDLINE] = "kernel_cmdline",
> +    [FW_CFG_INITRD_ADDR] = "initrd_addr",
> +    [FW_CFG_INITRD_SIZE] = "initdr_size",
> +    [FW_CFG_BOOT_DEVICE] = "boot_device",
> +    [FW_CFG_NUMA] = "numa",
> +    [FW_CFG_BOOT_MENU] = "boot_menu",
> +    [FW_CFG_MAX_CPUS] = "max_cpus",
> +    [FW_CFG_KERNEL_ENTRY] = "kernel_entry",
> +    [FW_CFG_KERNEL_DATA] = "kernel_data",
> +    [FW_CFG_INITRD_DATA] = "initrd_data",
> +    [FW_CFG_CMDLINE_ADDR] = "cmdline_addr",
> +    [FW_CFG_CMDLINE_SIZE] = "cmdline_size",
> +    [FW_CFG_CMDLINE_DATA] = "cmdline_data",
> +    [FW_CFG_SETUP_ADDR] = "setup_addr",
> +    [FW_CFG_SETUP_SIZE] = "setup_size",
> +    [FW_CFG_SETUP_DATA] = "setup_data",
> +    [FW_CFG_FILE_DIR] = "file_dir",
> +};

(2) I suggest introducing a macro that generates the initializer, using
the stringify() macro from "include/qemu/compiler.h". It should go
something like

#define FW_CFG_KEY_STRINGIFY(key) [key] = stringify(key),

Feel free to disagree though; this set of predefined, fixed numeric keys
will never change (nor will it ever be extened), so we might as well
live with the currently proposed verbosity.

> +
> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict)
> +{
> +    FWCfgState *s = fw_cfg_find();
> +    int arch, key;
> +
> +    monitor_printf(mon, "%12s %5s %7s %9s %6s %-24s\n",
> +                   "Type", "Perm", "Size", "Specific", "Order", "Info");
> +    for (arch = 0; arch < ARRAY_SIZE(s->entries); ++arch) {
> +        for (key = 0; key < fw_cfg_max_entry(s); ++key) {
> +            FWCfgEntry *e = &s->entries[arch][key];
> +            const char *perm = e->allow_write ? "RW" : "RO";
> +            const char *arch_spec = arch ? "arch_spec" : "";
> +            char *type, *info = NULL;
> +
> +            if (!e->len) {
> +                continue;
> +            }
> +            if (key >= FW_CFG_FILE_FIRST) {
> +                int id = key - FW_CFG_FILE_FIRST;
> +                const char *path = s->files->f[id].name;
> +
> +                type = g_strdup_printf("file (id %d)", id);
> +                monitor_printf(mon, "%12s %5s %7d %10s %5d %-24s\n",
> +                               type, perm, e->len, arch_spec,
> +                               get_fw_cfg_order(s, path), path);
> +                g_free(type);
> +                continue;
> +            }
> +            type = g_strdup(fw_cfg_wellknown_entries[key]);
> +            if (!type) {
> +                type = g_strdup_printf("entry_%d", key);
> +            }
> +
> +            switch (key) {
> +            case FW_CFG_SIGNATURE:
> +                info = g_strndup((const gchar *)e->data, e->len);
> +                break;
> +            case FW_CFG_UUID:
> +                info = qemu_uuid_unparse_strdup((const QemuUUID *)e->data);
> +                break;
> +            case FW_CFG_ID:
> +            case FW_CFG_NOGRAPHIC:
> +            case FW_CFG_NB_CPUS:
> +            case FW_CFG_BOOT_MENU:
> +            case FW_CFG_MAX_CPUS:
> +            case FW_CFG_RAM_SIZE:
> +            case FW_CFG_KERNEL_ADDR:
> +            case FW_CFG_KERNEL_SIZE:
> +            case FW_CFG_KERNEL_CMDLINE:
> +            case FW_CFG_KERNEL_ENTRY:
> +            case FW_CFG_KERNEL_DATA:
> +            case FW_CFG_INITRD_ADDR:
> +            case FW_CFG_INITRD_SIZE:
> +            case FW_CFG_INITRD_DATA:
> +            case FW_CFG_CMDLINE_ADDR:
> +            case FW_CFG_CMDLINE_SIZE:
> +            case FW_CFG_CMDLINE_DATA:
> +            case FW_CFG_SETUP_ADDR:
> +            case FW_CFG_SETUP_SIZE:
> +            case FW_CFG_SETUP_DATA:
> +                switch (e->len) {
> +                case 2:
> +                    info = g_strdup_printf("0x%04x", lduw_le_p(e->data));
> +                    break;
> +                case 4:
> +                    info = g_strdup_printf("0x%08x", ldl_le_p(e->data));
> +                    break;
> +                case 8:
> +                    info = g_strdup_printf("0x%016" PRIx64, ldq_le_p(e->data));
> +                    break;
> +                default:
> +                    break;
> +                }
> +                break;
> +            default:
> +                break;
> +            }
> +            monitor_printf(mon, "%12s %5s %7d %10s %5s %-24s\n",
> +                           type, perm, e->len, arch_spec, "", info ? info : "");
> +            g_free(type);
> +            g_free(info);
> +        }
> +    }
> +}

(3) In general I wouldn't try to be smart here, regarding the contents.
I suggest simply dumping arrays of uint8_t values, in hex.

(4) Also I wouldn't reuse the same column for different purposes; I
think it's easier to read if a column always means the same thing, and
if it doesn't apply, it's just left blank. Something like this:

  Selector  Well-Known Numeric  Pathname  Perm  Size  Arch-Spec  Order  Data

- "Selector" is the uint16 selector key
- "Well-Known Numeric" is the stringified name if the selector refers to
  a well-known numerically defined item.
- "Pathname" is the pathname for named files. Mutually exclusive with
  "Well-Known Numeric", but that's OK, IMO.
- "Arch-Spec" should be left blank, or marked as "set" with an asterisk.
- "Data" should be a hexdump of uint8_t values (normally limited to 8
  bytes, if the array is larger).

(5) I think this interface would benefit from being exposed over QMP /
JSON, and then the tabular presentation would be a separate question in
HMP.

(6) If we want bells and whistles, two optional parameters could be
considered: one for identifying one specific key to request info about
(identify by selector? well-known macro name? file pathname?), and
another param for placing a limit, different from 8, on the individual
hexdump size.


Important: these are not "requirements", just random ideas, food for
thought. I'm fine if you reject any subset of them, after consideration.
I don't intend this to spiral into feature creep; take whatever you
like.

Thanks!
Laszlo

> diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
> index f5a6895a74..28630b2f26 100644
> --- a/include/hw/nvram/fw_cfg.h
> +++ b/include/hw/nvram/fw_cfg.h
> @@ -226,4 +226,6 @@ FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
>  FWCfgState *fw_cfg_find(void);
>  bool fw_cfg_dma_enabled(void *opaque);
>
> +void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict);
> +
>  #endif
>
Philippe Mathieu-Daudé Dec. 18, 2018, 3:14 p.m. UTC | #6
Hi Michael,

On 12/10/18 10:18 AM, Philippe Mathieu-Daudé wrote:
> On 12/7/18 6:54 PM, Michael S. Tsirkin wrote:
>> On Fri, Dec 07, 2018 at 06:03:59PM +0100, Philippe Mathieu-Daudé wrote:
>>> $ qemu-system-x86_64 -S -monitor stdio
>>> (qemu) info fw_cfg
>>>         Type    Perm    Size    Specific   Order   Info
>>>    signature      RO       4                       QEMU
>>>           id      RO       4                       0x00000003
>>>         uuid      RO      16                       00000000-0000-0000-0000-000000000000
>>>     ram_size      RO       8                       0x0000000008000000
>>>    nographic      RO       2                       0x0000
>>>      nb_cpus      RO       2                       0x0001
>>>         numa      RO      16
>>>    boot_menu      RO       2                       0x0000
>>>     max_cpus      RO       2                       0x0001
>>>     file_dir      RO    2052
>>>  file (id 1)      RO      36                 160   etc/acpi/rsdp
>>>  file (id 2)      RO  131072                 130   etc/acpi/tables
>>>  file (id 3)      RO       4                  15   etc/boot-fail-wait
>>>  file (id 4)      RO      20                  40   etc/e820
>>>  file (id 5)      RO      31                  30   etc/smbios/smbios-anchor
>>>  file (id 6)      RO     320                  20   etc/smbios/smbios-tables
>>>  file (id 7)      RO       6                  90   etc/system-states
>>>  file (id 8)      RO    4096                 140   etc/table-loader
>>> file (id 10)      RO    9216                  55   genroms/kvmvapic.bin
>>>         uuid      RO       4  (arch spec)          01000000-0000-0000-0000-000000000000
>>>     ram_size      RO     324  (arch spec)
>>>    nographic      RO     121  (arch spec)
>>
>> Weird. Your code has arch_spec.
> 
> Hmmm I'll check that.

These are the entries used for Bochs:

#define FW_CFG_ACPI_TABLES (FW_CFG_ARCH_LOCAL + 0)
#define FW_CFG_SMBIOS_ENTRIES (FW_CFG_ARCH_LOCAL + 1)
#define FW_CFG_IRQ0_OVERRIDE (FW_CFG_ARCH_LOCAL + 2)
#define FW_CFG_E820_TABLE (FW_CFG_ARCH_LOCAL + 3)
#define FW_CFG_HPET (FW_CFG_ARCH_LOCAL + 4)

static FWCfgState *bochs_bios_init(AddressSpace *as, PCMachineState *pcms)
{
    [...]
    fw_cfg_add_bytes(fw_cfg, FW_CFG_ACPI_TABLES,
                     acpi_tables, acpi_tables_len);
    fw_cfg_add_i32(fw_cfg, FW_CFG_IRQ0_OVERRIDE,
                   kvm_allows_irq0_override());
    fw_cfg_add_bytes(fw_cfg, FW_CFG_E820_TABLE,
                     &e820_reserve, sizeof(e820_reserve));

So what happened here is the 'type' name is incorrect (I'll fix), but
the arch_spec flag is correct. Thanks for noticing this :)

Regards,

Phil.

Patch
diff mbox series

diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
index cbee8b944d..9e86dceeb4 100644
--- a/hmp-commands-info.hx
+++ b/hmp-commands-info.hx
@@ -916,6 +916,20 @@  STEXI
 @item info sev
 @findex info sev
 Show SEV information.
+ETEXI
+
+    {
+        .name       = "fw_cfg",
+        .args_type  = "",
+        .params     = "",
+        .help       = "Display the table of the fw_cfg entries registered",
+        .cmd        = hmp_info_fw_cfg,
+    },
+
+STEXI
+@item info fw_cfg
+@findex info fw_cfg
+Show roms.
 ETEXI
 
 STEXI
diff --git a/hw/nvram/fw_cfg.c b/hw/nvram/fw_cfg.c
index 582653f07e..50525ec1dd 100644
--- a/hw/nvram/fw_cfg.c
+++ b/hw/nvram/fw_cfg.c
@@ -36,6 +36,7 @@ 
 #include "qemu/config-file.h"
 #include "qemu/cutils.h"
 #include "qapi/error.h"
+#include "monitor/monitor.h"
 
 #define FW_CFG_FILE_SLOTS_DFLT 0x20
 
@@ -1164,3 +1165,117 @@  static void fw_cfg_register_types(void)
 }
 
 type_init(fw_cfg_register_types)
+
+static const char *fw_cfg_wellknown_entries[0x20] = {
+    [FW_CFG_SIGNATURE] = "signature",
+    [FW_CFG_ID] = "id",
+    [FW_CFG_UUID] = "uuid",
+    [FW_CFG_RAM_SIZE] = "ram_size",
+    [FW_CFG_NOGRAPHIC] = "nographic",
+    [FW_CFG_NB_CPUS] = "nb_cpus",
+    [FW_CFG_MACHINE_ID] = "machine_id",
+    [FW_CFG_KERNEL_ADDR] = "kernel_addr",
+    [FW_CFG_KERNEL_SIZE] = "kernel_size",
+    [FW_CFG_KERNEL_CMDLINE] = "kernel_cmdline",
+    [FW_CFG_INITRD_ADDR] = "initrd_addr",
+    [FW_CFG_INITRD_SIZE] = "initdr_size",
+    [FW_CFG_BOOT_DEVICE] = "boot_device",
+    [FW_CFG_NUMA] = "numa",
+    [FW_CFG_BOOT_MENU] = "boot_menu",
+    [FW_CFG_MAX_CPUS] = "max_cpus",
+    [FW_CFG_KERNEL_ENTRY] = "kernel_entry",
+    [FW_CFG_KERNEL_DATA] = "kernel_data",
+    [FW_CFG_INITRD_DATA] = "initrd_data",
+    [FW_CFG_CMDLINE_ADDR] = "cmdline_addr",
+    [FW_CFG_CMDLINE_SIZE] = "cmdline_size",
+    [FW_CFG_CMDLINE_DATA] = "cmdline_data",
+    [FW_CFG_SETUP_ADDR] = "setup_addr",
+    [FW_CFG_SETUP_SIZE] = "setup_size",
+    [FW_CFG_SETUP_DATA] = "setup_data",
+    [FW_CFG_FILE_DIR] = "file_dir",
+};
+
+void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict)
+{
+    FWCfgState *s = fw_cfg_find();
+    int arch, key;
+
+    monitor_printf(mon, "%12s %5s %7s %9s %6s %-24s\n",
+                   "Type", "Perm", "Size", "Specific", "Order", "Info");
+    for (arch = 0; arch < ARRAY_SIZE(s->entries); ++arch) {
+        for (key = 0; key < fw_cfg_max_entry(s); ++key) {
+            FWCfgEntry *e = &s->entries[arch][key];
+            const char *perm = e->allow_write ? "RW" : "RO";
+            const char *arch_spec = arch ? "arch_spec" : "";
+            char *type, *info = NULL;
+
+            if (!e->len) {
+                continue;
+            }
+            if (key >= FW_CFG_FILE_FIRST) {
+                int id = key - FW_CFG_FILE_FIRST;
+                const char *path = s->files->f[id].name;
+
+                type = g_strdup_printf("file (id %d)", id);
+                monitor_printf(mon, "%12s %5s %7d %10s %5d %-24s\n",
+                               type, perm, e->len, arch_spec,
+                               get_fw_cfg_order(s, path), path);
+                g_free(type);
+                continue;
+            }
+            type = g_strdup(fw_cfg_wellknown_entries[key]);
+            if (!type) {
+                type = g_strdup_printf("entry_%d", key);
+            }
+
+            switch (key) {
+            case FW_CFG_SIGNATURE:
+                info = g_strndup((const gchar *)e->data, e->len);
+                break;
+            case FW_CFG_UUID:
+                info = qemu_uuid_unparse_strdup((const QemuUUID *)e->data);
+                break;
+            case FW_CFG_ID:
+            case FW_CFG_NOGRAPHIC:
+            case FW_CFG_NB_CPUS:
+            case FW_CFG_BOOT_MENU:
+            case FW_CFG_MAX_CPUS:
+            case FW_CFG_RAM_SIZE:
+            case FW_CFG_KERNEL_ADDR:
+            case FW_CFG_KERNEL_SIZE:
+            case FW_CFG_KERNEL_CMDLINE:
+            case FW_CFG_KERNEL_ENTRY:
+            case FW_CFG_KERNEL_DATA:
+            case FW_CFG_INITRD_ADDR:
+            case FW_CFG_INITRD_SIZE:
+            case FW_CFG_INITRD_DATA:
+            case FW_CFG_CMDLINE_ADDR:
+            case FW_CFG_CMDLINE_SIZE:
+            case FW_CFG_CMDLINE_DATA:
+            case FW_CFG_SETUP_ADDR:
+            case FW_CFG_SETUP_SIZE:
+            case FW_CFG_SETUP_DATA:
+                switch (e->len) {
+                case 2:
+                    info = g_strdup_printf("0x%04x", lduw_le_p(e->data));
+                    break;
+                case 4:
+                    info = g_strdup_printf("0x%08x", ldl_le_p(e->data));
+                    break;
+                case 8:
+                    info = g_strdup_printf("0x%016" PRIx64, ldq_le_p(e->data));
+                    break;
+                default:
+                    break;
+                }
+                break;
+            default:
+                break;
+            }
+            monitor_printf(mon, "%12s %5s %7d %10s %5s %-24s\n",
+                           type, perm, e->len, arch_spec, "", info ? info : "");
+            g_free(type);
+            g_free(info);
+        }
+    }
+}
diff --git a/include/hw/nvram/fw_cfg.h b/include/hw/nvram/fw_cfg.h
index f5a6895a74..28630b2f26 100644
--- a/include/hw/nvram/fw_cfg.h
+++ b/include/hw/nvram/fw_cfg.h
@@ -226,4 +226,6 @@  FWCfgState *fw_cfg_init_mem_wide(hwaddr ctl_addr,
 FWCfgState *fw_cfg_find(void);
 bool fw_cfg_dma_enabled(void *opaque);
 
+void hmp_info_fw_cfg(Monitor *mon, const QDict *qdict);
+
 #endif