Re: [PATCH v4 00/14] Initial support for machine creation via QMP

[Jim Shu <jim.shu@sifive.com>]

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Hi all,

Thanks for the work!

I'm from SiFive and we are very interested in this feature.
QMP/QAPI configurable QEMU machine is a useful feature in our use case.
With this feature, we can both model our versatile FPGA-based platforms
more easily and model a new platform without modification of source code.
It is helpful for early software development of SoC prototyping.
We think this feature is also helpful to the QEMU community.

Also, I have tested this patchset (v4) and newer v5 patchset [1] with
Damien's firmware [2] and it works correctly.

p.s. QMP option "-qmp socket,path=./qmpsocket,server" in v5 patchset
instruction may not work?
I use the option "-qmp unix:./qmpsocket,server" instead.

[1] [PATCH v5 0/6] QAPI support for device cold-plug
https://lore.kernel.org/qemu-devel/20220519153402.41540-1-damien.hedde@greensocs.com/

[2] Test firmware for patchset
v5: https://github.com/GreenSocs/qemu-qmp-machines/tree/master/arm-virt
v4:
https://github.com/GreenSocs/qemu-qmp-machines/tree/eba16dab8b587e624d65c5c302aeef424bece3a0

On Thu, Mar 3, 2022 at 7:02 PM Damien Hedde <damien.hedde@greensocs.com>
wrote:

> Ping !
>
> It would be good to have some feedback on 1st and 2nd part.
>
> Thanks,
> Damien
>
> On 2/23/22 10:06, Damien Hedde wrote:
> > Hi,
> >
> > This series adds initial support to build a machine using QMP/QAPI
> > commands. With this series, one can start from the 'none' machine,
> > create cpus, sysbus devices, memory map them and wire interrupts.
> >
> > Sorry for the huge cc list on this cover-letter. Apart from people
> > who attended the kvm call about this topic, I've cc'ed you only
> > according to MAINTAINERS file.
> >
> > The series is divided in 4 parts which are independent of each other,
> > but we need the 4 parts to be able to use this mechanism:
> > + Patches 1 to 6 allow to use the qapi command device_add to cold
> >    plug devices (like CLI -device do)
> > + Patches 7 to 10 modify the 'none' machine which serves as base
> >    machine.
> > + Patches 11 to 13 handle memory mapping and memory creation
> > + Patches 14 allows dynamic cold plug of opentitan/sifive_e machine
> >    to build some example. This last patch is based on a cleanup
> >    series: it probably works without it, but some config errors are
> >    not handled (see based-on below).
> >
> > Only patch 11 is reviewed-by.
> >
> > v4:
> > + cold plugging approach changed in order not to conflict with
> >    startup. I do not add additional command to handle this so that
> >    we can change everything easily.
> > + device_add in cold plug context is also now equivalent to -device
> >    CLI regarding -fw_cfg. I also added patches to modify the 'none'
> >    machine.
> > + reworked most of the none machine part
> > + updated the sybus-mmio-map command patch
> >
> > Note that there are still lot of limitations (for example if you try
> > to create more cpus than the _max_cpus_, tcg will abort()).
> > Basically all tasks done by machine init reading some parameters are
> > really tricky: for example, loading complex firmware. But we have to
> > start by something and all this is not accessible unless the user
> > asked for none machine and -preconfig.
> >
> > I can maintain the code introduced here. I'm not sure what's the
> > process. Is there something else to do than propose a patch to
> > MAINTAINERS ?
> > If there is a global agreement on moving on with these feature, it
> > would be great to have a login on qemu wiki so I can document
> > limitations and the work being done to solve them.
> >
> > A simple test can be done with the following scenario which build
> > a machine subset of the opentitan.
> >
> > $ cat commands.qmp
> > // RAM 0x10000000
> > device_add driver=sysbus-memory id=ram size=0x4000 readonly=false
> > sysbus-mmio-map device=ram addr=268435456
> > // CPUS
> > device_add driver=riscv.hart_array id=cpus
> cpu-type=lowrisc-ibex-riscv-cpu num-harts=1 resetvec=0x8080
> > // ROM 0x00008000
> > device_add driver=sysbus-memory id=rom size=0x4000 readonly=true
> > sysbus-mmio-map device=rom addr=32768
> > // PLIC 0x48000000
> > device_add driver=riscv.sifive.plic id=plic hart-config=M hartid-base=0
> num-sources=180 num-priorities=3 priority-base=0x0 pending-base=0x1000
> enable-base=0x2000 enable-stride=32 context-base=0x200000 context-stride=8
> aperture-size=0x4005000
> > sysbus-mmio-map device=plic addr=1207959552
> > qom-set path=plic property=unnamed-gpio-out[1]
> value=cpus/harts[0]/unnamed-gpio-in[11]
> > // UART 0x40000000
> > device_add driver=ibex-uart id=uart chardev=serial0
> > sysbus-mmio-map device=uart addr=1073741824
> > qom-set path=uart property=sysbus-irq[1] value=plic/unnamed-gpio-in[2]
> > // FIRMWARE
> > device_add driver=loader cpu-num=0 file=/path/to/firmware.elf
> > x-exit-preconfig
> >
> > $ qemu-system-riscv32 -display none -M none -preconfig -serial stdio
> -qmp unix:/tmp/qmp-sock,server
> >
> > In another terminal, you'll need to send the commands with, for example:
> > $ grep -v '^//' commands.qmp | qmp-shell /tmp/qmp-sock -v
> >
> > It is the same as running
> > $ qemu-system-riscv32 -display none -M opentitan -serial stdio -kernel
> path/to/firmware.elf
> >
> > If you need a firmware, you can pick this one
> >
> https://github.com/GreenSocs/qemu-qmp-machines/blob/master/opentitan-echo.elf
> > This firmware is just a small interrupt-based bare-metal program
> > echoing back whatever is sent in the uart.
> >
> > This repo contains also sifive_e machine example.
> >
> > Based-on: <20220218164646.132112-1-damien.hedde@greensocs.com>
> > "RiscV cleanups for user-related life cycles"
> >
> > Thanks for your comments,
> > --
> > Damien
> >
> > Damien Hedde (13):
> >    machine: add phase_get() and document phase_check()/advance()
> >    machine&vl: introduce phase_until() to handle phase transitions
> >    vl: support machine-initialized target in phase_until()
> >    qapi/device_add: compute is_hotplug flag
> >    qapi/device_add: handle the rom_order_override when cold-plugging
> >    none-machine: add the NoneMachineState structure
> >    none-machine: add 'ram-addr' property
> >    none-machine: allow cold plugging sysbus devices
> >    none-machine: allow several cpus
> >    softmmu/memory: add memory_region_try_add_subregion function
> >    add sysbus-mmio-map qapi command
> >    hw/mem/system-memory: add a memory sysbus device
> >    hw: set user_creatable on opentitan/sifive_e devices
> >
> > Mirela Grujic (1):
> >    qapi/device_add: Allow execution in machine initialized phase
> >
> >   qapi/qdev.json                 | 34 +++++++++++-
> >   include/exec/memory.h          | 22 ++++++++
> >   include/hw/mem/sysbus-memory.h | 28 ++++++++++
> >   include/hw/qdev-core.h         | 33 ++++++++++++
> >   hw/char/ibex_uart.c            |  1 +
> >   hw/char/sifive_uart.c          |  1 +
> >   hw/core/null-machine.c         | 68 ++++++++++++++++++++++--
> >   hw/core/qdev.c                 |  5 ++
> >   hw/core/sysbus.c               | 49 ++++++++++++++++++
> >   hw/gpio/sifive_gpio.c          |  1 +
> >   hw/intc/riscv_aclint.c         |  2 +
> >   hw/intc/sifive_plic.c          |  1 +
> >   hw/mem/sysbus-memory.c         | 80 +++++++++++++++++++++++++++++
> >   hw/misc/sifive_e_prci.c        |  8 +++
> >   hw/misc/unimp.c                |  1 +
> >   hw/riscv/riscv_hart.c          |  1 +
> >   hw/timer/ibex_timer.c          |  1 +
> >   monitor/misc.c                 |  2 +-
> >   softmmu/memory.c               | 23 ++++++---
> >   softmmu/qdev-monitor.c         | 20 +++++++-
> >   softmmu/vl.c                   | 94 ++++++++++++++++++++++++++--------
> >   hmp-commands.hx                |  1 +
> >   hw/mem/meson.build             |  2 +
> >   23 files changed, 439 insertions(+), 39 deletions(-)
> >   create mode 100644 include/hw/mem/sysbus-memory.h
> >   create mode 100644 hw/mem/sysbus-memory.c
> >
>
>

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