Re: [PATCH 1/4] Add ivshmem-flat device

["Philippe Mathieu-Daudé" <philmd@linaro.org>]

On 27/11/23 06:20, Gustavo Romero wrote:
> Add a new device, ivshmem-flat, which is similar to the ivshmem PCI but
> does not require a PCI bus. It's meant to be used on machines like those
> with Cortex-M MCUs, which usually lack a PCI/PCIe bus, e.g. lm3s6965evb
> and mps2-an385.
> 
> The device currently only supports the sysbus bus.
> 
> The following is an example on how to create the ivshmem-flat device on
> a Stellaris machine:
> 
> $ qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic
>                    -net none -chardev stdio,id=con,mux=on
>                    -serial chardev:con -mon chardev=con,mode=readline
>                    -chardev socket,path=/tmp/ivshmem_socket,id=ivf
>                    -device ivshmem-flat,x-irq-qompath=/machine/unattached/device[1]/nvic/unnamed-gpio-in[0],x-bus-qompath="/sysbus",chardev=ivf
>                    -kernel zephyr_qemu.elf
> 
> The new device, just like the ivshmem PCI device, supports both peer
> notification via hardware interrupts and shared memory.
> 
> The IRQ QOM path for the target machine can be determined by creating
> the VM without the ivshmem-flat device, going to the QEMU console and
> listing the QOM nodes with 'info qom-tree'. In the Stellaris example
> above the input IRQ is in the NVIC IC.
> 
> The MMRs for status and control (notification) are mapped to the MMIO
> region at 0x400FF000 (default), whilst the shared memory region start
> is mapped at addr. 0x40100000 (default), but both addresses can be set
> when creating the device by using 'x-bus-address-{mmr,shmem}' options,
> respectively.
> 
> The device shared memory size can be set using the 'shmem-size' option
> and it defaults to 4 MiB, which is the default size of shmem allocated
> by the ivshmem server.
> 
> Signed-off-by: Gustavo Romero <gustavo.romero@linaro.org>
> ---
>   docs/system/devices/ivshmem-flat.rst |  89 +++++
>   hw/arm/mps2.c                        |   2 +
>   hw/arm/stellaris.c                   |   5 +-
>   hw/arm/virt.c                        |   2 +
>   hw/core/sysbus-fdt.c                 |   1 +
>   hw/misc/Kconfig                      |   5 +
>   hw/misc/ivshmem-flat.c               | 477 +++++++++++++++++++++++++++
>   hw/misc/meson.build                  |   2 +
>   hw/misc/trace-events                 |  18 +
>   include/hw/misc/ivshmem-flat.h       |  72 ++++
>   10 files changed, 672 insertions(+), 1 deletion(-)
>   create mode 100644 docs/system/devices/ivshmem-flat.rst
>   create mode 100644 hw/misc/ivshmem-flat.c
>   create mode 100644 include/hw/misc/ivshmem-flat.h


> diff --git a/include/hw/misc/ivshmem-flat.h b/include/hw/misc/ivshmem-flat.h
> new file mode 100644
> index 0000000000..2f6f7462f6
> --- /dev/null
> +++ b/include/hw/misc/ivshmem-flat.h
> @@ -0,0 +1,72 @@
> +/*
> + * Inter-VM Shared Memory Flat Device
> + *
> + * SPDX-FileCopyrightText: 2023 Linaro Ltd.
> + * SPDX-FileContributor: Gustavo Romero <gustavo.romero@linaro.org>
> + * SPDX-License-Identifier: GPL-2.0-or-later
> + *
> + */
> +
> +#ifndef IVSHMEM_FLAT_H
> +#define IVSHMEM_FLAT_H
> +

I had to include the following headers:

  #include "qemu/queue.h"
  #include "qemu/event_notifier.h"
  #include "chardev/char-fe.h"
  #include "exec/memory.h"
  #include "qom/object.h"
  #include "hw/sysbus.h"

in order to fix:

include/hw/misc/ivshmem-flat.h:50:19: error: field has incomplete type 
'EventNotifier' (aka 'struct EventNotifier')
     EventNotifier event_notifier;
                   ^
include/hw/misc/ivshmem-flat.h:55:5: error: type name requires a 
specifier or qualifier
     QTAILQ_ENTRY(IvshmemPeer) next;
     ^
include/hw/misc/ivshmem-flat.h:62:5: error: unknown type name 'SysBusDevice'
     SysBusDevice parent_obj;
     ^
include/hw/misc/ivshmem-flat.h:70:5: error: unknown type name 'CharBackend'
     CharBackend server_chr;
     ^
include/hw/misc/ivshmem-flat.h:76:18: error: field has incomplete type 
'MemoryRegion' (aka 'struct MemoryRegion')
     MemoryRegion iomem;
                  ^

> +#define IVSHMEM_MAX_VECTOR_NUM 64
> +
> +#define TYPE_IVSHMEM_FLAT "ivshmem-flat"
> +typedef struct IvshmemFTState IvshmemFTState;
> +
> +DECLARE_INSTANCE_CHECKER(IvshmemFTState, IVSHMEM_FLAT, TYPE_IVSHMEM_FLAT)
> +
> +/* Ivshmem registers. See ./docs/specs/ivshmem-spec.txt for details. */
> +enum ivshmem_registers {
> +    INTMASK = 0,
> +    INTSTATUS = 4,
> +    IVPOSITION = 8,
> +    DOORBELL = 12,
> +};
> +
> +typedef struct VectorInfo {
> +    EventNotifier event_notifier;
> +    uint16_t id;
> +} VectorInfo;
> +
> +typedef struct IvshmemPeer {
> +    QTAILQ_ENTRY(IvshmemPeer) next;
> +    VectorInfo vector[IVSHMEM_MAX_VECTOR_NUM];
> +    int vector_counter;
> +    uint16_t id;
> +} IvshmemPeer;
> +
> +struct IvshmemFTState {
> +    SysBusDevice parent_obj;
> +
> +    uint64_t msg_buf;
> +    int msg_buffered_bytes;
> +
> +    QTAILQ_HEAD(, IvshmemPeer) peer;
> +    IvshmemPeer own;
> +
> +    CharBackend server_chr;
> +
> +    char *bus_qompath;
> +
> +    /* IRQ */
> +    qemu_irq irq;
> +    char *irq_qompath;
> +
> +    /* MMRs */
> +    MemoryRegion iomem;
> +    uint64_t bus_address_mmr;
> +    uint32_t intmask;
> +    uint32_t intstatus;
> +    uint32_t ivposition;
> +    uint32_t doorbell;
> +
> +    /* Shared memory */
> +    MemoryRegion shmem;
> +    int shmem_fd;
> +    uint32_t shmem_size;
> +    uint64_t bus_address_shmem;
> +};
> +
> +#endif /* IVSHMEM_FLAT_H */