Re: [QEMU][PATCH v2 10/11] hw/arm: introduce xenpv machine

[Alex Bennée <alex.bennee@xxxxxxxxxx>]

Vikram Garhwal <vikram.garhwal@xxxxxxx> writes:

> Add a new machine xenpv which creates a IOREQ server to register/connect with
> Xen Hypervisor.
>
> Optional: When CONFIG_TPM is enabled, it also creates a tpm-tis-device, adds a
> TPM emulator and connects to swtpm running on host machine via chardev socket
> and support TPM functionalities for a guest domain.
>
> Extra command line for aarch64 xenpv QEMU to connect to swtpm:
>     -chardev socket,id=chrtpm,path=/tmp/myvtpm2/swtpm-sock \
>     -tpmdev emulator,id=tpm0,chardev=chrtpm \
>
> swtpm implements a TPM software emulator(TPM 1.2 & TPM 2) built on libtpms and
> provides access to TPM functionality over socket, chardev and CUSE interface.
> Github repo: https://github.com/stefanberger/swtpm
> Example for starting swtpm on host machine:
>     mkdir /tmp/vtpm2
>     swtpm socket --tpmstate dir=/tmp/vtpm2 \
>     --ctrl type=unixio,path=/tmp/vtpm2/swtpm-sock &
>
> /* Comment about machine name. Will be removed in next version*/
> Please reply with the machine name you agree. Below are two possible names:
> 1. xenpv
> 2. xenpvh
>
> Signed-off-by: Vikram Garhwal <vikram.garhwal@xxxxxxx>
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxx>
> ---
>  hw/arm/meson.build            |   2 +
>  hw/arm/xen_arm.c              | 175 ++++++++++++++++++++++++++++++++++
>  include/hw/arm/xen_arch_hvm.h |   9 ++
>  include/hw/xen/arch_hvm.h     |   2 +
>  4 files changed, 188 insertions(+)
>  create mode 100644 hw/arm/xen_arm.c
>  create mode 100644 include/hw/arm/xen_arch_hvm.h
>
> diff --git a/hw/arm/meson.build b/hw/arm/meson.build
> index 92f9f6e000..0cae024374 100644
> --- a/hw/arm/meson.build
> +++ b/hw/arm/meson.build
> @@ -62,5 +62,7 @@ arm_ss.add(when: 'CONFIG_FSL_IMX7', if_true: 
> files('fsl-imx7.c', 'mcimx7d-sabre.
>  arm_ss.add(when: 'CONFIG_ARM_SMMUV3', if_true: files('smmu-common.c', 
> 'smmuv3.c'))
>  arm_ss.add(when: 'CONFIG_FSL_IMX6UL', if_true: files('fsl-imx6ul.c', 
> 'mcimx6ul-evk.c'))
>  arm_ss.add(when: 'CONFIG_NRF51_SOC', if_true: files('nrf51_soc.c'))
> +arm_ss.add(when: 'CONFIG_XEN', if_true: files('xen_arm.c'))
> +arm_ss.add_all(xen_ss)
>  
>  hw_arch += {'arm': arm_ss}
> diff --git a/hw/arm/xen_arm.c b/hw/arm/xen_arm.c
> new file mode 100644
> index 0000000000..bcb8e95f2c
> --- /dev/null
> +++ b/hw/arm/xen_arm.c
> @@ -0,0 +1,175 @@
> +/*
> + * QEMU ARM Xen PV Machine
> + *
> + *
> + * 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 "qemu/error-report.h"
> +#include "qapi/qapi-commands-migration.h"
> +#include "hw/boards.h"
> +#include "hw/sysbus.h"
> +#include "sysemu/block-backend.h"
> +#include "sysemu/tpm_backend.h"
> +#include "sysemu/sysemu.h"
> +#include "hw/xen/xen-legacy-backend.h"
> +#include "hw/xen/xen-hvm-common.h"
> +#include "sysemu/tpm.h"
> +#include "hw/xen/arch_hvm.h"
> +
> +#define TYPE_XEN_ARM  MACHINE_TYPE_NAME("xenpv")
> +OBJECT_DECLARE_SIMPLE_TYPE(XenArmState, XEN_ARM)
> +
> +static MemoryListener xen_memory_listener = {
> +    .region_add = xen_region_add,
> +    .region_del = xen_region_del,
> +    .log_start = NULL,
> +    .log_stop = NULL,
> +    .log_sync = NULL,
> +    .log_global_start = NULL,
> +    .log_global_stop = NULL,
> +    .priority = 10,
> +};
> +
> +struct XenArmState {
> +    /*< private >*/
> +    MachineState parent;
> +
> +    XenIOState *state;
> +};
> +
> +void arch_handle_ioreq(XenIOState *state, ioreq_t *req)
> +{
> +    hw_error("Invalid ioreq type 0x%x\n", req->type);
> +
> +    return;
> +}
> +
> +void arch_xen_set_memory(XenIOState *state, MemoryRegionSection *section,
> +                         bool add)
> +{
> +}
> +
> +void xen_hvm_modified_memory(ram_addr_t start, ram_addr_t length)
> +{
> +}
> +
> +void qmp_xen_set_global_dirty_log(bool enable, Error **errp)
> +{
> +}
> +

This function is only used under CONFIG_TPM so without it you get:

  ../../hw/arm/xen_arm.c:78:12: error: ‘xen_init_ioreq’ defined but not used 
[-Werror=unused-function]
     78 | static int xen_init_ioreq(XenIOState *state, unsigned int max_cpus)
        |            ^~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

I think I reported this on v1 as well.

> +static int xen_init_ioreq(XenIOState *state, unsigned int max_cpus)
> +{
> +    xen_dmod = xendevicemodel_open(0, 0);
> +    if (xen_dmod == NULL) {
> +        perror("xen: can't open xen device model interface\n");
> +        return -1;
> +    }
> +
> +    xen_xc = xc_interface_open(0, 0, 0);
> +    if (xen_xc == NULL) {
> +        perror("xen: can't open xen interface\n");
> +        return -1;
> +    }
> +
> +    xen_fmem = xenforeignmemory_open(0, 0);
> +    if (xen_fmem == NULL) {
> +        perror("xen: can't open xen fmem interface\n");
> +        xc_interface_close(xen_xc);
> +        return -1;
> +    }
> +
> +    xen_register_ioreq(state, max_cpus, xen_memory_listener);
> +
> +    xen_register_backend(state);
> +
> +    xenstore_record_dm_state(state->xenstore, "running");
> +
> +    return 0;
> +}
> +
> +static void xen_enable_tpm(void)
> +{
> +/* qemu_find_tpm_be is only available when CONFIG_TPM is enabled. */
> +#ifdef CONFIG_TPM
> +    Error *errp = NULL;
> +    DeviceState *dev;
> +    SysBusDevice *busdev;
> +
> +    TPMBackend *be = qemu_find_tpm_be("tpm0");
> +    if (be == NULL) {
> +        DPRINTF("Couldn't fine the backend for tpm0\n");
> +        return;
> +    }
> +    dev = qdev_new(TYPE_TPM_TIS_SYSBUS);
> +    object_property_set_link(OBJECT(dev), "tpmdev", OBJECT(be), &errp);
> +    object_property_set_str(OBJECT(dev), "tpmdev", be->id, &errp);
> +    busdev = SYS_BUS_DEVICE(dev);
> +    sysbus_realize_and_unref(busdev, &error_fatal);
> +    sysbus_mmio_map(busdev, 0, GUEST_TPM_BASE);
> +
> +    DPRINTF("Connected tpmdev at address 0x%lx\n", GUEST_TPM_BASE);
> +#endif
> +}
> +
> +static void xen_arm_init(MachineState *machine)
> +{
> +    XenArmState *xam = XEN_ARM(machine);
> +
> +    xam->state =  g_new0(XenIOState, 1);
> +
> +    /* For now enable IOREQ only for CONFIG_TPM. */
> +#ifdef CONFIG_TPM
> +    if (xen_init_ioreq(xam->state, machine->smp.cpus)) {
> +        return;
> +    }
> +#endif
> +
> +    xen_enable_tpm();

In fact this just looks weird - you guard the call to init_ioreq with
ifdefs guarding it but nest those ifdefs in xen_enable_tpm. Surely you
want the IOREQ server support even if you don't have TPM. Otherwise it
should be a hard configure requirement.

> +
> +    return;
> +}
> +
> +static void xen_arm_machine_class_init(ObjectClass *oc, void *data)
> +{
> +
> +    MachineClass *mc = MACHINE_CLASS(oc);
> +    mc->desc = "Xen Para-virtualized PC";
> +    mc->init = xen_arm_init;
> +    mc->max_cpus = 1;
> +
> +#ifdef CONFIG_TPM
> +    machine_class_allow_dynamic_sysbus_dev(mc, TYPE_TPM_TIS_SYSBUS);
> +#endif
> +}
> +
> +static const TypeInfo xen_arm_machine_type = {
> +    .name = TYPE_XEN_ARM,
> +    .parent = TYPE_MACHINE,
> +    .class_init = xen_arm_machine_class_init,
> +    .instance_size = sizeof(XenArmState),
> +};
> +
> +static void xen_arm_machine_register_types(void)
> +{
> +    type_register_static(&xen_arm_machine_type);
> +}
> +
> +type_init(xen_arm_machine_register_types)
> diff --git a/include/hw/arm/xen_arch_hvm.h b/include/hw/arm/xen_arch_hvm.h
> new file mode 100644
> index 0000000000..8fd645e723
> --- /dev/null
> +++ b/include/hw/arm/xen_arch_hvm.h
> @@ -0,0 +1,9 @@
> +#ifndef HW_XEN_ARCH_ARM_HVM_H
> +#define HW_XEN_ARCH_ARM_HVM_H
> +
> +#include <xen/hvm/ioreq.h>
> +void arch_handle_ioreq(XenIOState *state, ioreq_t *req);
> +void arch_xen_set_memory(XenIOState *state,
> +                         MemoryRegionSection *section,
> +                         bool add);
> +#endif
> diff --git a/include/hw/xen/arch_hvm.h b/include/hw/xen/arch_hvm.h
> index 26674648d8..c7c515220d 100644
> --- a/include/hw/xen/arch_hvm.h
> +++ b/include/hw/xen/arch_hvm.h
> @@ -1,3 +1,5 @@
>  #if defined(TARGET_I386) || defined(TARGET_X86_64)
>  #include "hw/i386/xen_arch_hvm.h"
> +#elif defined(TARGET_ARM) || defined(TARGET_ARM_64)
> +#include "hw/arm/xen_arch_hvm.h"
>  #endif


-- 
Alex Bennée