Re: [Qemu-devel] hw/s390x/ipl: Dubious use of qdev_reset_all_fn

[Markus Armbruster]

Peter Maydell <address@hidden> writes:

> On Mon, 27 May 2019 at 08:52, Markus Armbruster <address@hidden> wrote:
>>
>> Peter Maydell <address@hidden> writes:
>> > Suggestions for how to restructure reset so this doesn't
>> > happen are welcome... "reset follows the bus hierarchy"
>> > works well in some places but is a bit weird in others
>> > (for SoC containers and the like "follow the QOM
>> > hierarchy" would make more sense, but I have no idea
>> > how to usefully transition to a model where you could
>> > say "for these devices, follow QOM tree for reset" or
>> > what an API for that would look like).
>>
>> Here's a QOM composition tree for the ARM virt machine (-nodefaults
>> -device e1000) as visible in qom-fuse under /machine, with irq and
>> qemu:memory-region ommitted for brevity:
>
> virt is a bit of an outlier because as a purely-virtual
> machine it has no "SoC" -- it's just a bag of devices
> at the machine level. It would be interesting to
> also look at a machine that's emulating something
> closer to real hardware (eg one of the aspeed machines,
> or mps2-an521).

Here you go: witherspoon-bmc (aspeed SoC) with -nodefaults and -device
m25p80 -device m25p80,id=qdev-id.  The -device are purely for
illustrating how user-plugged devices get added to the two trees.  I'm
not claiming they make sense.

QOM composition tree as visible in qom-fuse under /machine, with irq and
qemu:memory-region ommitted for brevity:

    machine  witherspoon-bmc-machine
      +-- peripheral  container
      |     +-- qdev-id  m25p80
      +-- peripheral-anon  container
      |     +-- device[0]  m25p80
      +-- soc  ast2500-a1
      |     +-- cpu  arm1176-arm-cpu
      |     +-- fmc  aspeed.smc.ast2500-fmc
      |     |     +-- spi  SSI
      |     +-- ftgmac100  ftgmac100
      |     +-- i2c  aspeed.i2c
      |     |     +-- aspeed.i2c.0  i2c-bus
      |     |     .
      |     |     .   more i2c-bus
      |     |     .
      |     |     +-- aspeed.i2c.13  i2c-bus
      |     +-- scu  aspeed.scu
      |     +-- sdmc  aspeed.sdmc
      |     +-- spi[0]  aspeed.smc.ast2500-spi1
      |     |     +-- spi  SSI
      |     +-- spi[1]  aspeed.smc.ast2500-spi2
      |     |     +-- spi  SSI
      |     +-- timerctrl  aspeed.timer
      |     +-- vic  aspeed.vic
      |     +-- wdt[0]  aspeed.wdt
      |     +-- wdt[1]  aspeed.wdt
      |     +-- wdt[2]  aspeed.wdt
      +-- unattached  container
            +-- device[0]  unimplemented-device
            +-- device[1]  mx25l25635e
            +-- device[2]  mx25l25635e
            +-- device[3]  mx66l1g45g
            +-- device[4]  pca9552
            +-- device[5]  tmp423
            +-- device[6]  tmp423
            +-- device[7]  tmp105
            +-- device[8]  ds1338
            +-- device[9]  smbus-eeprom
            +-- device[10]  pca9552
            +-- sysbus  System

Observations (same as for ARM virt, more or less):

* Where ARM virt had its onboard components as direct children of
  machine, witherspoon-bmc-machine has them wrapped in soc ast2500-a1.

* machine additionally has a few containers: peripheral,
  peripheral-anon, unattached.

* machine/peripheral and machine/peripheral-anon contain the -device
  with and without ID, respectively.

* machine/unattached contains everything else created by code without an
  explicit parent device.  Some (all?) of them should perhaps be direct
  children of machine or (unlike ARM virt) soc instead.

qdev tree shown by info qtree:

    bus: main-system-bus
      type System
      dev: unimplemented-device, id ""
        size = 2097152 (0x200000)
        name = "aspeed_soc.io"
        mmio 000000001e600000/0000000000200000
      dev: ftgmac100, id ""
        gpio-out "sysbus-irq" 1
        aspeed = true
        mac = "52:54:00:12:34:56"
        netdev = ""
        mmio 000000001e660000/0000000000002000
      dev: aspeed.wdt, id ""
        silicon-rev = 67175171 (0x4010303)
        mmio 000000001e785040/0000000000000020
      dev: aspeed.wdt, id ""
        silicon-rev = 67175171 (0x4010303)
        mmio 000000001e785020/0000000000000020
      dev: aspeed.wdt, id ""
        silicon-rev = 67175171 (0x4010303)
        mmio 000000001e785000/0000000000000020
      dev: aspeed.sdmc, id ""
        silicon-rev = 67175171 (0x4010303)
        ram-size = 536870912 (0x20000000)
        max-ram-size = 1073741824 (0x40000000)
        mmio 000000001e6e0000/0000000000001000
      dev: aspeed.smc.ast2500-spi2, id ""
        gpio-out "sysbus-irq" 2
        num-cs = 1 (0x1)
        mmio 000000001e631000/0000000000000100
        mmio 0000000038000000/0000000008000000
        bus: spi
          type SSI
          dev: m25p80, id "qdev-id"
            gpio-in "ssi-gpio-cs" 1
            nonvolatile-cfg = 36863 (0x8fff)
            spansion-cr1nv = 0 (0x0)
            spansion-cr2nv = 8 (0x8)
            spansion-cr3nv = 2 (0x2)
            spansion-cr4nv = 16 (0x10)
            drive = ""
          dev: m25p80, id ""
            gpio-in "ssi-gpio-cs" 1
            nonvolatile-cfg = 36863 (0x8fff)
            spansion-cr1nv = 0 (0x0)
            spansion-cr2nv = 8 (0x8)
            spansion-cr3nv = 2 (0x2)
            spansion-cr4nv = 16 (0x10)
            drive = ""
      dev: aspeed.smc.ast2500-spi1, id ""
        gpio-out "sysbus-irq" 2
        num-cs = 1 (0x1)
        mmio 000000001e630000/0000000000000100
        mmio 0000000030000000/0000000008000000
        bus: spi
          type SSI
          dev: mx66l1g45g, id ""
            gpio-in "ssi-gpio-cs" 1
            nonvolatile-cfg = 36863 (0x8fff)
            spansion-cr1nv = 0 (0x0)
            spansion-cr2nv = 8 (0x8)
            spansion-cr3nv = 2 (0x2)
            spansion-cr4nv = 16 (0x10)
            drive = ""
      dev: aspeed.smc.ast2500-fmc, id ""
        gpio-out "sysbus-irq" 3
        num-cs = 2 (0x2)
        mmio 000000001e620000/0000000000000100
        mmio 0000000020000000/0000000010000000
        bus: spi
          type SSI
          dev: mx25l25635e, id ""
            gpio-in "ssi-gpio-cs" 1
            nonvolatile-cfg = 36863 (0x8fff)
            spansion-cr1nv = 0 (0x0)
            spansion-cr2nv = 8 (0x8)
            spansion-cr3nv = 2 (0x2)
            spansion-cr4nv = 16 (0x10)
            drive = ""
          dev: mx25l25635e, id ""
            gpio-in "ssi-gpio-cs" 1
            nonvolatile-cfg = 36863 (0x8fff)
            spansion-cr1nv = 0 (0x0)
            spansion-cr2nv = 8 (0x8)
            spansion-cr3nv = 2 (0x2)
            spansion-cr4nv = 16 (0x10)
            drive = ""
      dev: aspeed.i2c, id ""
        gpio-out "sysbus-irq" 1
        mmio 000000001e78a000/0000000000001000
        bus: aspeed.i2c.13
          type i2c-bus
        ... more i2c-bus
        bus: aspeed.i2c.0
          type i2c-bus
      dev: aspeed.timer, id ""
        gpio-out "sysbus-irq" 8
        mmio 000000001e782000/0000000000001000
      dev: aspeed.vic, id ""
        gpio-out "sysbus-irq" 2
        gpio-in "" 51
        mmio 000000001e6c0000/0000000000020000
      dev: aspeed.scu, id ""
        silicon-rev = 67175171 (0x4010303)
        hw-strap1 = 4044018182 (0xf10ad206)
        hw-strap2 = 0 (0x0)
        hw-prot-key = 0 (0x0)
        mmio 000000001e6e2000/0000000000001000

Observations (same as for ARM virt):

* machine's containers are not in the qtree.

* Composition tree node arm1176-arm-cpu is not in the qtree.  That's
  because it isn't connected to a qbus.

  Same for pca9552, tmp423, tmp105, ds1338, smbus-eeprom, I guess.

* In the qtree, every other inner node is a qbus.  These are *leaves* in
  the composition tree.  The qtree's vertex from qbus to qdev is a
  *link* in the composition tree.

  Example: main-system-bus -> scu is
      machine/unattached/sysbus/child[0] ->
      ../../../machine/soc/scu.

  Example: main-system-bus -> unimplemented-device is
      machine/unattached/sysbus/child[12] ->
      ../../../machine/unattached/device[12].

  Example: main-system-bus/aspeed.smc.ast2500-spi1/spi -> mx66l1g45g is
      machine/soc/spi\[0\]/spi/child[0] ->
      ../../../../machine/unattached/device[3].

  Example: main-system-bus/aspeed.smc.ast2500-spi2/spi -> m25p80
      (the one without a qdev ID) is
      machine/soc/spi\[1\]/spi/child[0] ->
      ../../../../machine/peripheral-anon/device[0]

  Example: main-system-bus/aspeed.smc.ast2500-spi2/spi -> m25p80
      (the one with qdev ID "qdev-id") is
      machine/soc/spi\[1\]/spi/child[1] ->
      ../../../../machine/peripheral/qdev-id