Re: [Qemu-devel] [PATCH V2] hw/misc: Add simple measurement hardware

["Stefan Berger" <stefanb@us.ibm.com>]

Matthew Garrett <mjg59@coreos.com> wrote on 08/05/2016 07:17:12 PM:


> 
> Trusted Boot is based around having a trusted store of measurement data 
and
> a secure communications channel between that store and an attestation
> target. In actual hardware, that's a TPM. Since the TPM can only be 
accessed
> via the host system, this in turn requires that the TPM be able to 
perform
> reasonably complicated cryptographic functions in order to demonstrate 
its
> trusted state.
> 
> In cloud environments, qemu is inherently trusted and the hypervisor
> infrastructure provides a trusted mechanism for extracting information 
from
> qemu and providing it to another system. This means we can skip the 
crypto
> and stick with the basic functionality - ie, providing a trusted store 
of
> measurement data.
> 
> This driver provides a very small subset of TPM 1.2 functionality in the
> form of a bank of registers that can store SHA1 measurements of boot
> components. Performing a write to one of these registers will append the 
new
> 20 byte hash to the 20 bytes currently stored within the register, take 
a
> SHA1 of this 40 byte value and then replace the existing register 
contents
> with the new value. This ensures that a given value can only be obtained 
by
> performing the same sequence of writes. It also adds a monitor command 
to
> allow an external agent to extract this information from the running 
system
> and provide it over a secure communications channel. Finally, it 
measures
> each of the loaded ROMs into one of the registers at reset time.
> 
> In combination with work in SeaBIOS and the kernel, this permits a fully
> measured boot in a virtualised environment without the overhead of a 
full
> TPM implementation.
> 
> This version of the implementation depends on port io, but if there's
> interest I'll add mmio as well.

Port io is x86 specific, right? I don't think it should stay an x86 
specific device.


> 
> Signed-off-by: Matthew Garrett <mjg59@coreos.com>
> ---
> 
> This should cover the initial review feedback, with the exception of 
porting
> it to MMIO. It seems easier to keep it in port io space on x86, and I'll 
add
> MMIO support once it looks like we're happy with this implementation.
> 
>  default-configs/x86_64-softmmu.mak |   1 +
>  hmp-commands-info.hx               |  14 ++
>  hmp.c                              |  13 ++
>  hmp.h                              |   1 +
>  hw/core/loader.c                   |  12 ++
>  hw/i386/acpi-build.c               |  29 +++-
>  hw/misc/Makefile.objs              |   1 +
>  hw/misc/measurements.c             | 295 ++++++++++++++++++++++++++
> +++++++++++
>  hw/misc/measurements.h             |   4 +
>  include/hw/isa/isa.h               |  13 ++
>  include/hw/loader.h                |   1 +
>  monitor.c                          |   1 +
>  qapi-schema.json                   |  26 ++++
>  qmp-commands.hx                    |  20 +++
>  stubs/Makefile.objs                |   1 +
>  stubs/measurements.c               |  18 +++
>  16 files changed, 448 insertions(+), 2 deletions(-)
>  create mode 100644 hw/misc/measurements.c
>  create mode 100644 hw/misc/measurements.h
>  create mode 100644 stubs/measurements.c
> 
> diff --git a/default-configs/x86_64-softmmu.mak b/default-configs/
> x86_64-softmmu.mak
> index 6e3b312..6f0fcc3 100644
> --- a/default-configs/x86_64-softmmu.mak
> +++ b/default-configs/x86_64-softmmu.mak
> @@ -58,3 +58,4 @@ CONFIG_IOH3420=y
>  CONFIG_I82801B11=y
>  CONFIG_SMBIOS=y
>  CONFIG_HYPERV_TESTDEV=$(CONFIG_KVM)
> +CONFIG_MEASUREMENTS=y
> diff --git a/hmp-commands-info.hx b/hmp-commands-info.hx
> index 74446c6..bf1cf67 100644
> --- a/hmp-commands-info.hx
> +++ b/hmp-commands-info.hx
> @@ -816,6 +816,20 @@ STEXI
>  Show information about hotpluggable CPUs
>  ETEXI
> 
> +    {
> +        .name       = "measurements",
> +        .args_type  = "",
> +        .params     = "",
> +        .help       = "show PCR measurements",
> +        .mhandler.cmd = hmp_info_measurements,
> +    },
> +
> +STEXI
> +@item info measurements
> +@findex measurements
> +Show PCR measurements
> +ETEXI
> +
>  STEXI
>  @end table
>  ETEXI
> diff --git a/hmp.c b/hmp.c
> index cc2056e..c2ef869 100644
> --- a/hmp.c
> +++ b/hmp.c
> @@ -2038,6 +2038,19 @@ void hmp_info_iothreads(Monitor *mon, const 
> QDict *qdict)
>      qapi_free_IOThreadInfoList(info_list);
>  }
> 
> +void hmp_info_measurements(Monitor *mon, const QDict *qdict)
> +{
> +    MeasurementList *info_list = qmp_query_measurements(NULL);
> +    MeasurementList *info;
> +
> +    for (info = info_list; info; info = info->next) {
> +        monitor_printf(mon, "%02ld: %s\n", info->value->pcr,
> +                       info->value->hash);
> +    }
> +
> +    qapi_free_MeasurementList(info_list);
> +}
> +
>  void hmp_qom_list(Monitor *mon, const QDict *qdict)
>  {
>      const char *path = qdict_get_try_str(qdict, "path");
> diff --git a/hmp.h b/hmp.h
> index 0876ec0..6afb1d9 100644
> --- a/hmp.h
> +++ b/hmp.h
> @@ -40,6 +40,7 @@ void hmp_info_pci(Monitor *mon, const QDict *qdict);
>  void hmp_info_block_jobs(Monitor *mon, const QDict *qdict);
>  void hmp_info_tpm(Monitor *mon, const QDict *qdict);
>  void hmp_info_iothreads(Monitor *mon, const QDict *qdict);
> +void hmp_info_measurements(Monitor *mon, const QDict *qdict);
>  void hmp_quit(Monitor *mon, const QDict *qdict);
>  void hmp_stop(Monitor *mon, const QDict *qdict);
>  void hmp_system_reset(Monitor *mon, const QDict *qdict);
> diff --git a/hw/core/loader.c b/hw/core/loader.c
> index 53e0e41..d7ed110 100644
> --- a/hw/core/loader.c
> +++ b/hw/core/loader.c
> @@ -55,6 +55,7 @@
>  #include "exec/address-spaces.h"
>  #include "hw/boards.h"
>  #include "qemu/cutils.h"
> +#include "hw/misc/measurements.h"
> 
>  #include <zlib.h>
> 
> @@ -1026,6 +1027,17 @@ static void rom_reset(void *unused)
>      }
>  }
> 
> +void measure_roms(void)
> +{
> +    Rom *rom;
> +    QTAILQ_FOREACH(rom, &roms, next) {
> +        if (rom->data == NULL) {
> +            continue;
> +        }
> +        measurements_extend_data(0, rom->data, rom->datasize, 
rom->name);
> +    }
> +}
> +
>  int rom_check_and_register_reset(void)
>  {
>      hwaddr addr = 0;
> diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
> index a26a4bb..c9b5f12 100644
> --- a/hw/i386/acpi-build.c
> +++ b/hw/i386/acpi-build.c
> @@ -34,6 +34,7 @@
>  #include "hw/acpi/acpi-defs.h"
>  #include "hw/acpi/acpi.h"
>  #include "hw/acpi/cpu.h"
> +#include "hw/misc/measurements.h"
>  #include "hw/nvram/fw_cfg.h"
>  #include "hw/acpi/bios-linker-loader.h"
>  #include "hw/loader.h"
> @@ -115,6 +116,7 @@ typedef struct AcpiMiscInfo {
>      unsigned dsdt_size;
>      uint16_t pvpanic_port;
>      uint16_t applesmc_io_base;
> +    uint16_t measurements_io_base;
>  } AcpiMiscInfo;
> 
>  typedef struct AcpiBuildPciBusHotplugState {
> @@ -211,6 +213,7 @@ static void acpi_get_misc_info(AcpiMiscInfo *info)
>      info->tpm_version = tpm_get_version();
>      info->pvpanic_port = pvpanic_port();
>      info->applesmc_io_base = applesmc_port();
> +    info->measurements_io_base = measurements_port();
>  }
> 
>  /*
> @@ -2282,6 +2285,26 @@ build_dsdt(GArray *table_data, BIOSLinker 
*linker,
>          aml_append(dsdt, scope);
>      }
> 
> +    if (misc->measurements_io_base) {
> +        scope = aml_scope("\\_SB.PCI0.ISA");
> +        dev = aml_device("PCRS");
> +
> +        aml_append(dev, aml_name_decl("_HID", aml_string("CORE0001")));
> +        /* device present, functioning, decoding, not shown in UI */
> +        aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
> +
> +        crs = aml_resource_template();
> +        aml_append(crs,
> +               aml_io(AML_DECODE16, misc->measurements_io_base,
> +                      misc->measurements_io_base,
> +                      0x01, 2)
> +        );
> +        aml_append(dev, aml_name_decl("_CRS", crs));
> +
> +        aml_append(scope, dev);
> +        aml_append(dsdt, scope);
> +    }
> +
>      sb_scope = aml_scope("\\_SB");
>      {
>          build_memory_devices(sb_scope, nr_mem, pm->mem_hp_io_base,
> @@ -2689,11 +2712,13 @@ void acpi_build(AcpiBuildTables *tables, 
> MachineState *machine)
>          acpi_add_table(table_offsets, tables_blob);
>          build_hpet(tables_blob, tables->linker);
>      }
> -    if (misc.tpm_version != TPM_VERSION_UNSPEC) {
> +    if (misc.tpm_version != TPM_VERSION_UNSPEC || 
> misc.measurements_io_base) {
>          acpi_add_table(table_offsets, tables_blob);
>          build_tpm_tcpa(tables_blob, tables->linker, tables->tcpalog);
> 

If this device is hitchhiking on the TPM's ACPI tables, then are you also 
making this device mutually exclusive with the TPM ? Of not please do so.


> -        if (misc.tpm_version == TPM_VERSION_2_0) {
> +        if (misc.measurements_io_base) {
> +            measurements_set_log(tables->tcpalog->data);
> +        } else if (misc.tpm_version == TPM_VERSION_2_0) {
>              acpi_add_table(table_offsets, tables_blob);
>              build_tpm2(tables_blob, tables->linker);
>          }
> diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
> index 4cfbd10..b76e60c 100644
> --- a/hw/misc/Makefile.objs
> +++ b/hw/misc/Makefile.objs
> @@ -5,6 +5,7 @@ common-obj-$(CONFIG_ISA_DEBUG) += debugexit.o
>  common-obj-$(CONFIG_SGA) += sga.o
>  common-obj-$(CONFIG_ISA_TESTDEV) += pc-testdev.o
>  common-obj-$(CONFIG_PCI_TESTDEV) += pci-testdev.o
> +common-obj-$(CONFIG_MEASUREMENTS) += measurements.o
> 
>  obj-$(CONFIG_VMPORT) += vmport.o
> 
> diff --git a/hw/misc/measurements.c b/hw/misc/measurements.c
> new file mode 100644
> index 0000000..4d55f81
> --- /dev/null
> +++ b/hw/misc/measurements.c
> @@ -0,0 +1,295 @@
> +/*
> + * QEMU boot measurement
> + *
> + * Copyright (c) 2016 CoreOS, Inc <mjg59@coreos.com>
> + *
> + * Permission is hereby granted, free of charge, to any person 
obtaining a
> + * copy of this software and associated documentation files (the
> + * "Software"), to deal in the Software without restriction, including
> + * without limitation the rights to use, copy, modify, merge, publish,
> + * distribute, sublicense, and/or sell copies of the Software, and to 
permit
> + * persons to whom the Software is furnished to do so, subject to the
> + * following conditions:
> + *
> + * The above copyright notice and this permission notice shall be 
included
> + * in all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
EXPRESS
> + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
NONINFRINGEMENT. IN
> + * NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 
CLAIM,
> + * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT 
OR
> + * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE 
OR THE
> + * USE OR OTHER DEALINGS IN THE SOFTWARE.
> + */
> +#include "qemu/osdep.h"
> +#include "crypto/hash.h"
> +#include "monitor/monitor.h"
> +#include "hw/loader.h"
> +#include "hw/isa/isa.h"
> +#include "hw/misc/measurements.h"
> +#include "qmp-commands.h"
> +
> +#define MEASUREMENT(obj) OBJECT_CHECK(MeasurementState, (obj), 
> TYPE_MEASUREMENTS)
> +
> +#define DIGEST_SIZE 20
> +#define PCR_COUNT 24
> +
> +typedef struct MeasurementState MeasurementState;
> +
> +struct MeasurementState {
> +    ISADevice parent_obj;
> +    MemoryRegion io_select;
> +    MemoryRegion io_value;
> +    uint16_t iobase;
> +    uint8_t measurements[PCR_COUNT][DIGEST_SIZE];
> +    uint8_t tmpmeasurement[DIGEST_SIZE];
> +    int write_count;
> +    int read_count;
> +    uint8_t pcr;
> +    int logsize;
> +    struct tpm_event *log;
> +};
> +
> +struct tpm_event {
> +    uint32_t pcrindex;
> +    uint32_t eventtype;
> +    uint8_t digest[DIGEST_SIZE];
> +    uint32_t eventdatasize;
> +    uint8_t event[0];
> +};
> +
> +static Object *measurement_dev_find(void)
> +{
> +    return object_resolve_path_type("", TYPE_MEASUREMENTS, NULL);
> +}
> +
> +static void measurement_reset(DeviceState *dev)
> +{
> +    MeasurementState *s = MEASUREMENT(dev);
> +
> +    s->read_count = 0;
> +    s->write_count = 0;
> +    s->logsize = 0;
> +    memset(s->measurements, 0, sizeof(s->measurements));
> +    measure_roms();
> +}
> +
> +static void measurement_select(void *opaque, hwaddr addr, uint64_t 
> val, unsigned size)
> +{
> +    MeasurementState *s = MEASUREMENT(opaque);
> +
> +    if (val > PCR_COUNT)
> +        return;
> +
> +    s->pcr = val;
> +    s->read_count = 0;
> +    s->write_count = 0;
> +}
> +
> +static uint64_t measurement_version(void *opaque, hwaddr addr, unsigned 
size)
> +{
> +    return 0;
> +}
> +
> +static uint64_t measurement_read(void *opaque, hwaddr addr, unsigned 
size)
> +{
> +    MeasurementState *s = MEASUREMENT(opaque);
> +
> +    if (s->read_count == DIGEST_SIZE) {
> +        s->read_count = 0;
> +    }
> +    return s->measurements[s->pcr][s->read_count++];
> +}
> +
> +static void extend(MeasurementState *s, int pcrnum, uint8_t *data)
> +{
> +    Error *err;
> +    char tmpbuf[40];
> +    size_t resultlen = 0;
> +    uint8_t *result = NULL;
> +
> +    memcpy(tmpbuf, s->measurements[pcrnum], DIGEST_SIZE);
> +    memcpy(tmpbuf + DIGEST_SIZE, data, DIGEST_SIZE);
> +    if (qcrypto_hash_bytes(QCRYPTO_HASH_ALG_SHA1, tmpbuf, 40, 
> &result, &resultlen, &err) == 0) {
> +        memcpy(s->measurements[pcrnum], result, DIGEST_SIZE);
> +    } else {
> +        const char *msg = error_get_pretty(err);
> +        fprintf(stderr, "Failed to measure data: %s\n", msg);
> +        error_free(err);
> +    }
> +
> +    g_free(result);
> +}
> +
> +static void measurement_value(void *opaque, hwaddr addr, uint64_t 
> val, unsigned size)
> +{
> +    MeasurementState *s = opaque;
> +
> +    s->tmpmeasurement[s->write_count++] = val;
> +    if (s->write_count == DIGEST_SIZE) {
> +        extend(s, s->pcr, s->tmpmeasurement);
> +        s->write_count = 0;
> +    }
> +}
> +
> +static void log_data(MeasurementState *s, int pcrnum, uint8_t 
> *hash, char *description)
> +{
> +    int eventlen = strlen(description);
> +    int entrylen = eventlen + sizeof(struct tpm_event);
> +    struct tpm_event *logentry;
> +
> +    if (!s->log)
> +        return;
> +
> +    logentry = (struct tpm_event *)(((void *)s->log) + s->logsize);
> +    logentry->pcrindex = pcrnum;
> +    logentry->eventtype = 1;
> +    memcpy(logentry->digest, hash, DIGEST_SIZE);
> +    logentry->eventdatasize = eventlen;
> +    memcpy(logentry->event, description, eventlen);
> +
> +    s->logsize += entrylen;
> +}
> +
> +void measurements_extend_data(int pcrnum, uint8_t *data, size_t 
> len, char *description)
> +{
> +    int ret;
> +    Error *err;
> +    uint8_t *result;
> +    size_t resultlen = 0;
> +    Object *obj = object_resolve_path_type("", TYPE_MEASUREMENTS, 
NULL);
> +
> +    if (!obj) {
> +        return;
> +    }
> +
> +    ret = qcrypto_hash_bytes(QCRYPTO_HASH_ALG_SHA1, (char *)data, 
> len, &result,
> +                             &resultlen, &err);
> +    if (ret < 0) {
> +        const char *msg = error_get_pretty(err);
> +        fprintf(stderr, "Failed to hash extension data: %s\n", msg);
> +        return;
> +    }
> +
> +    extend(MEASUREMENT(obj), pcrnum, result);
> +    log_data(MEASUREMENT(obj), pcrnum, result, description);
> +    g_free(result);
> +}
> +
> +static const MemoryRegionOps measurement_select_ops = {
> +    .write = measurement_select,
> +    .read = measurement_version,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .impl = {
> +        .min_access_size = 1,
> +        .max_access_size = 1,
> +    },
> +};
> +
> +static const MemoryRegionOps measurement_value_ops = {
> +    .write = measurement_value,
> +    .read = measurement_read,
> +    .endianness = DEVICE_NATIVE_ENDIAN,
> +    .impl = {
> +        .min_access_size = 1,
> +        .max_access_size = 1,
> +    },
> +};
> +
> +static void measurement_realize(DeviceState *dev, Error **errp)
> +{
> +    MeasurementState *s = MEASUREMENT(dev);
> +
> +    memory_region_init_io(&s->io_select, OBJECT(s), 
&measurement_select_ops,
> +                          s, "measurement-select", 1);
> +    isa_register_ioport(&s->parent_obj, &s->io_select, s->iobase);
> +    memory_region_init_io(&s->io_value, OBJECT(s), 
&measurement_value_ops, s,
> +                          "measurement-value", 1);
> +    isa_register_ioport(&s->parent_obj, &s->io_value, s->iobase + 1);
> +    measurement_reset(dev);
> +}
> +
> +static Property measurement_props[] = {
> +    DEFINE_PROP_UINT16(MEASUREMENTS_PROP_IO_BASE, MeasurementState, 
iobase,
> +                       0x620),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static const VMStateDescription measurement_state = {
> +    .name = "measurements",
> +    .version_id = 1,
> +    .minimum_version_id = 1,
> +    .fields = (VMStateField[]) {
> +        VMSTATE_UINT16(iobase, MeasurementState),
> +        VMSTATE_BUFFER_UNSAFE(measurements, MeasurementState, 0, 
> PCR_COUNT * DIGEST_SIZE),
> +        VMSTATE_BUFFER(tmpmeasurement, MeasurementState),
> +        VMSTATE_INT32(write_count, MeasurementState),
> +        VMSTATE_INT32(read_count, MeasurementState),
> +        VMSTATE_UINT8(pcr, MeasurementState),
> +        VMSTATE_END_OF_LIST()
> +    }
> +};
> +
> +static void measurement_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    dc->realize = measurement_realize;
> +    dc->reset = measurement_reset;
> +    dc->props = measurement_props;
> +    dc->vmsd = &measurement_state;
> +    set_bit(DEVICE_CATEGORY_MISC, dc->categories);
> +}
> +
> +static const TypeInfo measurement = {
> +    .name          = TYPE_MEASUREMENTS,
> +    .parent        = TYPE_ISA_DEVICE,
> +    .instance_size = sizeof(MeasurementState),
> +    .class_init    = measurement_class_init,
> +};
> +
> +static void measurement_register_types(void)
> +{
> +    type_register_static(&measurement);
> +}
> +
> +type_init(measurement_register_types);
> +
> +MeasurementList *qmp_query_measurements(Error **errp)
> +{
> +    MeasurementList *head = NULL;
> +    MeasurementList **prev = &head;
> +    MeasurementList *elem;
> +    Measurement *info;
> +    Object *obj = object_resolve_path_type("", TYPE_MEASUREMENTS, 
NULL);
> +    MeasurementState *s;
> +    int pcr, i;
> +
> +    if (!obj) {
> +        return NULL;
> +    }
> +
> +    s = MEASUREMENT(obj);
> +
> +    for (pcr = 0; pcr < PCR_COUNT; pcr++) {
> +        info = g_new0(Measurement, 1);
> +        info->pcr = pcr;
> +        info->hash = g_malloc0(DIGEST_SIZE*2+1);
> +        for (i = 0; i < DIGEST_SIZE; i++) {
> +            sprintf(info->hash + i * 2, "%02x", 
s->measurements[pcr][i]);
> +        }
> +        elem = g_new0(MeasurementList, 1);
> +        elem->value = info;
> +        *prev = elem;
> +        prev = &elem->next;
> +    }
> +    return head;
> +}
> +
> +void measurements_set_log(gchar *log)
> +{
> +    Object *obj = measurement_dev_find();
> +    MeasurementState *s = MEASUREMENT(obj);
> +
> +    s->log = (struct tpm_event *)log;
> +}
> diff --git a/hw/misc/measurements.h b/hw/misc/measurements.h
> new file mode 100644
> index 0000000..7cb8db2
> --- /dev/null
> +++ b/hw/misc/measurements.h
> @@ -0,0 +1,4 @@
> +#include "hw/sysbus.h"
> +
> +void measurements_extend_data(int pcrnum, uint8_t *data, size_t 
> len, char *description);
> +void measurements_set_log(gchar *log);
> diff --git a/include/hw/isa/isa.h b/include/hw/isa/isa.h
> index 7693ac5..55e5472 100644
> --- a/include/hw/isa/isa.h
> +++ b/include/hw/isa/isa.h
> @@ -24,6 +24,9 @@
>  #define APPLESMC_MAX_DATA_LENGTH       32
>  #define APPLESMC_PROP_IO_BASE "iobase"
> 
> +#define TYPE_MEASUREMENTS "measurements"
> +#define MEASUREMENTS_PROP_IO_BASE "iobase"
> +
>  static inline uint16_t applesmc_port(void)
>  {
>      Object *obj = object_resolve_path_type("", TYPE_APPLE_SMC, NULL);
> @@ -34,6 +37,16 @@ static inline uint16_t applesmc_port(void)
>      return 0;
>  }
> 
> +static inline uint16_t measurements_port(void)
> +{
> +    Object *obj = object_resolve_path_type("", TYPE_MEASUREMENTS, 
NULL);
> +
> +    if (obj) {
> +        return object_property_get_int(obj, MEASUREMENTS_PROP_IO_BASE, 
NULL);
> +    }
> +    return 0;
> +}
> +
>  #define TYPE_ISADMA "isa-dma"
> 
>  #define ISADMA_CLASS(klass) \
> diff --git a/include/hw/loader.h b/include/hw/loader.h
> index 4879b63..cc3157d 100644
> --- a/include/hw/loader.h
> +++ b/include/hw/loader.h
> @@ -133,6 +133,7 @@ void rom_reset_order_override(void);
>  int rom_copy(uint8_t *dest, hwaddr addr, size_t size);
>  void *rom_ptr(hwaddr addr);
>  void hmp_info_roms(Monitor *mon, const QDict *qdict);
> +void measure_roms(void);
> 
>  #define rom_add_file_fixed(_f, _a, _i)          \
>      rom_add_file(_f, NULL, _a, _i, false, NULL)
> diff --git a/monitor.c b/monitor.c
> index 5d68a5d..3affc90 100644
> --- a/monitor.c
> +++ b/monitor.c
> @@ -32,6 +32,7 @@
>  #include "hw/pci/pci.h"
>  #include "sysemu/watchdog.h"
>  #include "hw/loader.h"
> +#include "hw/misc/measurements.h"
>  #include "exec/gdbstub.h"
>  #include "net/net.h"
>  #include "net/slirp.h"
> diff --git a/qapi-schema.json b/qapi-schema.json
> index 5658723..6151fcd 100644
> --- a/qapi-schema.json
> +++ b/qapi-schema.json
> @@ -4338,3 +4338,29 @@
>  # Since: 2.7
>  ##
>  { 'command': 'query-hotpluggable-cpus', 'returns': ['HotpluggableCPU'] 
}
> +
> +##
> +# @Measurement
> +#
> +# @pcr: The PCR in the measurement
> +# @value: The hash value
> +# @vcpus-count: number of logical VCPU threads @HotpluggableCPU 
provides
> +# @qom-path: #optional link to existing CPU object if CPU is present or
> +#            omitted if CPU is not present.
> +#
> +# Since: 2.7
> +##
> +{ 'struct': 'Measurement',
> +  'data': { 'pcr': 'int',
> +            'hash': 'str'
> +          }
> +}
> +
> +##
> +# @query-measurements
> +#
> +# Returns: a list of Measurement objects
> +#
> +# Since: 2.7
> +##
> +{ 'command': 'query-measurements', 'returns': ['Measurement'] }
> diff --git a/qmp-commands.hx b/qmp-commands.hx
> index c8d360a..a13f939 100644
> --- a/qmp-commands.hx
> +++ b/qmp-commands.hx
> @@ -5041,3 +5041,23 @@ Example for pc machine type started with
>              "props": {"core-id": 0, "socket-id": 0, "thread-id": 0}
>           }
>         ]}
> +
> +EQMP
> +    {
> +        .name       = "query-measurements",
> +        .args_type  = "",
> +        .mhandler.cmd_new = qmp_marshal_query_measurements,
> +    },
> +SQMP
> +Show system measurements
> +------------------------
> +
> +Arguments: None.
> +
> +Example:
> +
> +-> { "execute": "query-measurements" }
> +<- {"return": [
> +     { "pcr": 0, "hash": "2cfb9f764876a5c7a3a96770fb79043353a5fa38"},
> +     { "pcr": 1, "hash": "30b2c318442bd985ce9394ff649056ffde691617"}
> +     ]}'
> diff --git a/stubs/Makefile.objs b/stubs/Makefile.objs
> index 55edd15..0ec2f7b 100644
> --- a/stubs/Makefile.objs
> +++ b/stubs/Makefile.objs
> @@ -45,3 +45,4 @@ stub-obj-y += iohandler.o
>  stub-obj-y += smbios_type_38.o
>  stub-obj-y += ipmi.o
>  stub-obj-y += pc_madt_cpu_entry.o
> +stub-obj-y += measurements.o
> diff --git a/stubs/measurements.c b/stubs/measurements.c
> new file mode 100644
> index 0000000..49fc4bd
> --- /dev/null
> +++ b/stubs/measurements.c
> @@ -0,0 +1,18 @@
> +#include "qemu/osdep.h"
> +#include "hw/misc/measurements.h"
> +#include "qmp-commands.h"
> +
> +MeasurementList *qmp_query_measurements(Error **errp)
> +{
> +    return NULL;
> +}
> +
> +void measurements_extend_data(int pcrnum, uint8_t *data, size_t 
> len, char *description)
> +{
> +    return;
> +}
> +
> +void measurements_set_log(gchar *log)
> +{
> +    return;
> +}
> -- 
> 2.7.4
>