Re: [PATCH v3 11/14] hw/vmapple/bdif: Introduce vmapple backdoor interface

[Phil Dennis-Jordan <phil@philjordan.eu>]

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On Sat, 5 Oct 2024 at 07:12, Akihiko Odaki <akihiko.odaki@daynix.com> wrote:

> On 2024/09/28 17:57, Phil Dennis-Jordan wrote:
> > From: Alexander Graf <graf@amazon.com>
> >
> > The VMApple machine exposes AUX and ROOT block devices (as well as USB
> OTG
> > emulation) via virtio-pci as well as a special, simple backdoor platform
> > device.
> >
> > This patch implements this backdoor platform device to the best of my
> > understanding. I left out any USB OTG parts; they're only needed for
> > guest recovery and I don't understand the protocol yet.
> >
> > Signed-off-by: Alexander Graf <graf@amazon.com>
> > Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
> > ---
> >   hw/vmapple/Kconfig        |   3 +
> >   hw/vmapple/bdif.c         | 245 ++++++++++++++++++++++++++++++++++++++
> >   hw/vmapple/meson.build    |   1 +
> >   hw/vmapple/trace-events   |   5 +
> >   include/hw/vmapple/bdif.h |  31 +++++
> >   5 files changed, 285 insertions(+)
> >   create mode 100644 hw/vmapple/bdif.c
> >   create mode 100644 include/hw/vmapple/bdif.h
> >
> > diff --git a/hw/vmapple/Kconfig b/hw/vmapple/Kconfig
> > index a73504d5999..68f88876eb9 100644
> > --- a/hw/vmapple/Kconfig
> > +++ b/hw/vmapple/Kconfig
> > @@ -1,3 +1,6 @@
> >   config VMAPPLE_AES
> >       bool
> >
> > +config VMAPPLE_BDIF
> > +    bool
> > +
> > diff --git a/hw/vmapple/bdif.c b/hw/vmapple/bdif.c
> > new file mode 100644
> > index 00000000000..36b5915ff30
> > --- /dev/null
> > +++ b/hw/vmapple/bdif.c
> > @@ -0,0 +1,245 @@
> > +/*
> > + * VMApple Backdoor Interface
> > + *
> > + * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights
> Reserved.
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or
> later.
> > + * See the COPYING file in the top-level directory.
> > + */
> > +
> > +#include "qemu/osdep.h"
> > +#include "hw/vmapple/bdif.h"
> > +#include "qemu/log.h"
> > +#include "qemu/module.h"
> > +#include "qapi/error.h"
> > +#include "trace.h"
> > +#include "hw/block/block.h"
> > +#include "sysemu/block-backend.h"
> > +
> > +#define REG_DEVID_MASK      0xffff0000
> > +#define DEVID_ROOT          0x00000000
> > +#define DEVID_AUX           0x00010000
> > +#define DEVID_USB           0x00100000
> > +
> > +#define REG_STATUS          0x0
> > +#define REG_STATUS_ACTIVE     BIT(0)
> > +#define REG_CFG             0x4
> > +#define REG_CFG_ACTIVE        BIT(1)
> > +#define REG_UNK1            0x8
> > +#define REG_BUSY            0x10
> > +#define REG_BUSY_READY        BIT(0)
> > +#define REG_UNK2            0x400
> > +#define REG_CMD             0x408
> > +#define REG_NEXT_DEVICE     0x420
> > +#define REG_UNK3            0x434
> > +
> > +typedef struct vblk_sector {
>
> Please use VblkSector for the tag name too.
>
> > +    uint32_t pad;
> > +    uint32_t pad2;
> > +    uint32_t sector;
> > +    uint32_t pad3;
> > +} VblkSector;
> > +
> > +typedef struct vblk_req_cmd {
> > +    uint64_t addr;
> > +    uint32_t len;
> > +    uint32_t flags;
> > +} VblkReqCmd;
> > +
> > +typedef struct vblk_req {
> > +    VblkReqCmd sector;
> > +    VblkReqCmd data;
> > +    VblkReqCmd retval;
> > +} VblkReq;
> > +
> > +#define VBLK_DATA_FLAGS_READ  0x00030001
> > +#define VBLK_DATA_FLAGS_WRITE 0x00010001
> > +
> > +#define VBLK_RET_SUCCESS  0
> > +#define VBLK_RET_FAILED   1
> > +
> > +static uint64_t bdif_read(void *opaque, hwaddr offset, unsigned size)
> > +{
> > +    uint64_t ret = -1;
> > +    uint64_t devid = (offset & REG_DEVID_MASK);
>
> The parenthes in this line are unnecessary.
>
> > +
> > +    switch (offset & ~REG_DEVID_MASK) {
> > +    case REG_STATUS:
> > +        ret = REG_STATUS_ACTIVE;
> > +        break;
> > +    case REG_CFG:
> > +        ret = REG_CFG_ACTIVE;
> > +        break;
> > +    case REG_UNK1:
> > +        ret = 0x420;
> > +        break;
> > +    case REG_BUSY:
> > +        ret = REG_BUSY_READY;
> > +        break;
> > +    case REG_UNK2:
> > +        ret = 0x1;
> > +        break;
> > +    case REG_UNK3:
> > +        ret = 0x0;
> > +        break;
> > +    case REG_NEXT_DEVICE:
> > +        switch (devid) {
> > +        case DEVID_ROOT:
> > +            ret = 0x8000000;
> > +            break;
> > +        case DEVID_AUX:
> > +            ret = 0x10000;
> > +            break;
> > +        }
> > +        break;
> > +    }
> > +
> > +    trace_bdif_read(offset, size, ret);
> > +    return ret;
> > +}
> > +
> > +static void le2cpu_sector(VblkSector *sector)
> > +{
> > +    sector->sector = le32_to_cpu(sector->sector);
> > +}
> > +
> > +static void le2cpu_reqcmd(VblkReqCmd *cmd)
> > +{
> > +    cmd->addr = le64_to_cpu(cmd->addr);
> > +    cmd->len = le32_to_cpu(cmd->len);
> > +    cmd->flags = le32_to_cpu(cmd->flags);
> > +}
> > +
> > +static void le2cpu_req(VblkReq *req)
> > +{
> > +    le2cpu_reqcmd(&req->sector);
> > +    le2cpu_reqcmd(&req->data);
> > +    le2cpu_reqcmd(&req->retval);
> > +}
> > +
> > +static void vblk_cmd(uint64_t devid, BlockBackend *blk, uint64_t value,
> > +                     uint64_t static_off)
> > +{
> > +    VblkReq req;
> > +    VblkSector sector;
> > +    uint64_t off = 0;
> > +    char *buf = NULL;
> > +    uint8_t ret = VBLK_RET_FAILED;
> > +    int r;
> > +
> > +    cpu_physical_memory_read(value, &req, sizeof(req));
> > +    le2cpu_req(&req);
> > +
> > +    if (req.sector.len != sizeof(sector)) {
> > +        ret = VBLK_RET_FAILED;
> > +        goto out;
> > +    }
> > +
> > +    /* Read the vblk command */
> > +    cpu_physical_memory_read(req.sector.addr, &sector, sizeof(sector));
> > +    le2cpu_sector(&sector);
> > +
> > +    off = sector.sector * 512ULL + static_off;
> > +
> > +    /* Sanity check that we're not allocating bogus sizes */
> > +    if (req.data.len > (128 * 1024 * 1024)) {
>
> Use MiB defined in: include/qemu/units.h
> The parentheses on the right hand are also unnecessary.
>
> > +        goto out;
> > +    }
> > +
> > +    buf = g_malloc0(req.data.len);
> > +    switch (req.data.flags) {
> > +    case VBLK_DATA_FLAGS_READ:
> > +        r = blk_pread(blk, off, req.data.len, buf, 0);
> > +        trace_bdif_vblk_read(devid == DEVID_AUX ? "aux" : "root",
> > +                             req.data.addr, off, req.data.len, r);
> > +        if (r < 0) {
> > +            goto out;
> > +        }
> > +        cpu_physical_memory_write(req.data.addr, buf, req.data.len);
> > +        ret = VBLK_RET_SUCCESS;
> > +        break;
> > +    case VBLK_DATA_FLAGS_WRITE:
> > +        /* Not needed, iBoot only reads */
> > +        break;
> > +    default:
> > +        break;
> > +    }
> > +
> > +out:
> > +    g_free(buf);
> > +    cpu_physical_memory_write(req.retval.addr, &ret, 1);
> > +}
> > +
> > +static void bdif_write(void *opaque, hwaddr offset,
> > +                       uint64_t value, unsigned size)
> > +{
> > +    VMAppleBdifState *s = opaque;
> > +    uint64_t devid = (offset & REG_DEVID_MASK);
> > +
> > +    trace_bdif_write(offset, size, value);
> > +
> > +    switch (offset & ~REG_DEVID_MASK) {
> > +    case REG_CMD:
> > +        switch (devid) {
> > +        case DEVID_ROOT:
> > +            vblk_cmd(devid, s->root, value, 0x0);
> > +            break;
> > +        case DEVID_AUX:
> > +            vblk_cmd(devid, s->aux, value, 0x0);
> > +            break;
> > +        }
> > +        break;
> > +    }
> > +}
> > +
> > +static const MemoryRegionOps bdif_ops = {
> > +    .read = bdif_read,
> > +    .write = bdif_write,
> > +    .endianness = DEVICE_NATIVE_ENDIAN,
> > +    .valid = {
> > +        .min_access_size = 1,
> > +        .max_access_size = 8,
> > +    },
> > +    .impl = {
> > +        .min_access_size = 1,
> > +        .max_access_size = 8,
> > +    },
> > +};
> > +
> > +static void bdif_init(Object *obj)
> > +{
> > +    VMAppleBdifState *s = VMAPPLE_BDIF(obj);
> > +
> > +    memory_region_init_io(&s->mmio, obj, &bdif_ops, obj,
> > +                         "VMApple Backdoor Interface",
> VMAPPLE_BDIF_SIZE);
> > +    sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->mmio);
> > +}
> > +
> > +static Property bdif_properties[] = {
> > +    DEFINE_PROP_DRIVE("aux", VMAppleBdifState, aux),
> > +    DEFINE_PROP_DRIVE("root", VMAppleBdifState, root),
> > +    DEFINE_PROP_END_OF_LIST(),
> > +};
> > +
> > +static void bdif_class_init(ObjectClass *klass, void *data)
> > +{
> > +    DeviceClass *dc = DEVICE_CLASS(klass);
> > +
> > +    dc->desc = "VMApple Backdoor Interface";
> > +    device_class_set_props(dc, bdif_properties);
> > +}
> > +
> > +static const TypeInfo bdif_info = {
> > +    .name          = TYPE_VMAPPLE_BDIF,
> > +    .parent        = TYPE_SYS_BUS_DEVICE,
> > +    .instance_size = sizeof(VMAppleBdifState),
> > +    .instance_init = bdif_init,
> > +    .class_init    = bdif_class_init,
> > +};
> > +
> > +static void bdif_register_types(void)
> > +{
> > +    type_register_static(&bdif_info);
> > +}
> > +
> > +type_init(bdif_register_types)
> > diff --git a/hw/vmapple/meson.build b/hw/vmapple/meson.build
> > index bcd4dcb28d2..d4624713deb 100644
> > --- a/hw/vmapple/meson.build
> > +++ b/hw/vmapple/meson.build
> > @@ -1 +1,2 @@
> >   system_ss.add(when: 'CONFIG_VMAPPLE_AES',  if_true: files('aes.c'))
> > +system_ss.add(when: 'CONFIG_VMAPPLE_BDIF', if_true: files('bdif.c'))
> > diff --git a/hw/vmapple/trace-events b/hw/vmapple/trace-events
> > index 1c9a3326eb4..fc8e9cc5897 100644
> > --- a/hw/vmapple/trace-events
> > +++ b/hw/vmapple/trace-events
> > @@ -19,3 +19,8 @@ aes_2_write_unknown(uint64_t offset) "offset=0x%"PRIx64
> >   aes_2_write(uint64_t offset, uint64_t val) "offset=0x%"PRIx64"
> val=0x%"PRIx64
> >   aes_dump_data(const char *desc, const char *hex) "%s%s"
> >
> > +# bdif.c
> > +bdif_read(uint64_t offset, uint32_t size, uint64_t value)
> "offset=0x%"PRIx64" size=0x%x value=0x%"PRIx64
> > +bdif_write(uint64_t offset, uint32_t size, uint64_t value)
> "offset=0x%"PRIx64" size=0x%x value=0x%"PRIx64
> > +bdif_vblk_read(const char *dev, uint64_t addr, uint64_t offset,
> uint32_t len, int r) "dev=%s addr=0x%"PRIx64" off=0x%"PRIx64" size=0x%x
> r=%d"
> > +
> > diff --git a/include/hw/vmapple/bdif.h b/include/hw/vmapple/bdif.h
> > new file mode 100644
> > index 00000000000..65ee43457b9
> > --- /dev/null
> > +++ b/include/hw/vmapple/bdif.h
> > @@ -0,0 +1,31 @@
> > +/*
> > + * VMApple Backdoor Interface
> > + *
> > + * Copyright © 2023 Amazon.com, Inc. or its affiliates. All Rights
> Reserved.
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or
> later.
> > + * See the COPYING file in the top-level directory.
> > + */
> > +
> > +#ifndef HW_VMAPPLE_BDIF_H
> > +#define HW_VMAPPLE_BDIF_H
> > +
> > +#include "hw/sysbus.h"
> > +#include "qom/object.h"
> > +
> > +#define TYPE_VMAPPLE_BDIF "vmapple-bdif"
> > +OBJECT_DECLARE_SIMPLE_TYPE(VMAppleBdifState, VMAPPLE_BDIF)
> > +
> > +struct VMAppleBdifState {
> > +    /* <private> */
> > +    SysBusDevice parent_obj;
> > +
> > +    /* <public> */
> > +    BlockBackend *aux;
> > +    BlockBackend *root;
> > +    MemoryRegion mmio;
> > +};
> > +
> > +#define VMAPPLE_BDIF_SIZE 0x00200000
>
> Please move VMAppleBdifState and VMAPPLE_BDIF_SIZE into: hw/vmapple/bdif.c
> They are both private.
>

Hmm, the same thing applies to the cfg device and the virtio-blk extension;
the only thing that's actually interesting to have in a header file are the
device type string definitions, so I think I'll put all of them in a single
/include/hw/vmapple/vmapple.h file.


> > +
> > +#endif /* HW_VMAPPLE_BDIF_H */
>
>

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