Re: [Qemu-devel] [PULL 03/36] hw/pci: delay bus_master_enable_region initialization

[Mark Cave-Ayland]

On 04/07/16 17:46, Michael S. Tsirkin wrote:

> From: Marcel Apfelbaum <address@hidden>
> 
> Skip bus_master_enable region creation on PCI device init
> in order to be sure the IOMMU device (if present) would
> be created in advance. Add this memory region at machine_done time.
> 
> Signed-off-by: Marcel Apfelbaum <address@hidden>
> Reviewed-by: Michael S. Tsirkin <address@hidden>
> Signed-off-by: Michael S. Tsirkin <address@hidden>
> ---
>  include/hw/pci/pci_bus.h |  2 ++
>  include/sysemu/sysemu.h  |  1 +
>  hw/pci/pci.c             | 41 ++++++++++++++++++++++++++++++++---------
>  vl.c                     |  5 +++++
>  4 files changed, 40 insertions(+), 9 deletions(-)
> 
> diff --git a/include/hw/pci/pci_bus.h b/include/hw/pci/pci_bus.h
> index 403fec6..5484a9b 100644
> --- a/include/hw/pci/pci_bus.h
> +++ b/include/hw/pci/pci_bus.h
> @@ -39,6 +39,8 @@ struct PCIBus {
>         Keep a count of the number of devices with raised IRQs.  */
>      int nirq;
>      int *irq_count;
> +
> +    Notifier machine_done;
>  };
>  
>  typedef struct PCIBridgeWindows PCIBridgeWindows;
> diff --git a/include/sysemu/sysemu.h b/include/sysemu/sysemu.h
> index 7313673..ee7c760 100644
> --- a/include/sysemu/sysemu.h
> +++ b/include/sysemu/sysemu.h
> @@ -75,6 +75,7 @@ void qemu_add_exit_notifier(Notifier *notify);
>  void qemu_remove_exit_notifier(Notifier *notify);
>  
>  void qemu_add_machine_init_done_notifier(Notifier *notify);
> +void qemu_remove_machine_init_done_notifier(Notifier *notify);
>  
>  void hmp_savevm(Monitor *mon, const QDict *qdict);
>  int load_vmstate(const char *name);
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 4b585f4..ee385eb 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -78,10 +78,37 @@ static const VMStateDescription vmstate_pcibus = {
>      }
>  };
>  
> +static void pci_init_bus_master(PCIDevice *pci_dev)
> +{
> +    AddressSpace *dma_as = pci_device_iommu_address_space(pci_dev);
> +
> +    memory_region_init_alias(&pci_dev->bus_master_enable_region,
> +                             OBJECT(pci_dev), "bus master",
> +                             dma_as->root, 0, 
> memory_region_size(dma_as->root));
> +    memory_region_set_enabled(&pci_dev->bus_master_enable_region, false);
> +    address_space_init(&pci_dev->bus_master_as,
> +                       &pci_dev->bus_master_enable_region, pci_dev->name);
> +}
> +
> +static void pcibus_machine_done(Notifier *notifier, void *data)
> +{
> +    PCIBus *bus = container_of(notifier, PCIBus, machine_done);
> +    int i;
> +
> +    for (i = 0; i < ARRAY_SIZE(bus->devices); ++i) {
> +        if (bus->devices[i]) {
> +            pci_init_bus_master(bus->devices[i]);
> +        }
> +    }
> +}
> +
>  static void pci_bus_realize(BusState *qbus, Error **errp)
>  {
>      PCIBus *bus = PCI_BUS(qbus);
>  
> +    bus->machine_done.notify = pcibus_machine_done;
> +    qemu_add_machine_init_done_notifier(&bus->machine_done);
> +
>      vmstate_register(NULL, -1, &vmstate_pcibus, bus);
>  }
>  
> @@ -89,6 +116,8 @@ static void pci_bus_unrealize(BusState *qbus, Error **errp)
>  {
>      PCIBus *bus = PCI_BUS(qbus);
>  
> +    qemu_remove_machine_init_done_notifier(&bus->machine_done);
> +
>      vmstate_unregister(NULL, &vmstate_pcibus, bus);
>  }
>  
> @@ -920,7 +949,6 @@ static PCIDevice *do_pci_register_device(PCIDevice 
> *pci_dev, PCIBus *bus,
>      PCIConfigReadFunc *config_read = pc->config_read;
>      PCIConfigWriteFunc *config_write = pc->config_write;
>      Error *local_err = NULL;
> -    AddressSpace *dma_as;
>      DeviceState *dev = DEVICE(pci_dev);
>  
>      pci_dev->bus = bus;
> @@ -961,15 +989,10 @@ static PCIDevice *do_pci_register_device(PCIDevice 
> *pci_dev, PCIBus *bus,
>  
>      pci_dev->devfn = devfn;
>      pci_dev->requester_id_cache = pci_req_id_cache_get(pci_dev);
> -    dma_as = pci_device_iommu_address_space(pci_dev);
> -
> -    memory_region_init_alias(&pci_dev->bus_master_enable_region,
> -                             OBJECT(pci_dev), "bus master",
> -                             dma_as->root, 0, 
> memory_region_size(dma_as->root));
> -    memory_region_set_enabled(&pci_dev->bus_master_enable_region, false);
> -    address_space_init(&pci_dev->bus_master_as, 
> &pci_dev->bus_master_enable_region,
> -                       name);
>  
> +    if (qdev_hotplug) {
> +        pci_init_bus_master(pci_dev);
> +    }
>      pstrcpy(pci_dev->name, sizeof(pci_dev->name), name);
>      pci_dev->irq_state = 0;
>      pci_config_alloc(pci_dev);
> diff --git a/vl.c b/vl.c
> index 9bb7f4c..5cd0f2a 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -2675,6 +2675,11 @@ void qemu_add_machine_init_done_notifier(Notifier 
> *notify)
>      }
>  }
>  
> +void qemu_remove_machine_init_done_notifier(Notifier *notify)
> +{
> +    notifier_remove(notify);
> +}
> +
>  static void qemu_run_machine_init_done_notifiers(void)
>  {
>      notifier_list_notify(&machine_init_done_notifiers, NULL);
> 

Unfortunately this patch causes a regression booting my Debian 7.8.0 and
NetBSD 7.0 test images under qemu-system-sparc64 when accessing the
CDROM device, and rather unusually causes the qemu-system-sparc64
executable itself to segfault:


Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffe8453700 (LWP 21454)]
0x000000000041494a in address_space_lookup_region (d=0x0,
addr=3221225472, resolve_subpage=true) at
/home/build/src/qemu/git/qemu/exec.c:359
359         MemoryRegionSection *section = atomic_read(&d->mru_section);
(gdb) bt
#0  0x000000000041494a in address_space_lookup_region (d=0x0,
addr=3221225472, resolve_subpage=true) at
/home/build/src/qemu/git/qemu/exec.c:359
#1  0x0000000000414aa7 in address_space_translate_internal (d=0x0,
addr=3221225472, xlat=0x7fffe8451c40, plen=0x7fffe8451d10,
resolve_subpage=true) at /home/build/src/qemu/git/qemu/exec.c:390
#2  0x0000000000414c8f in address_space_translate (as=0x1961600,
addr=3221225472, xlat=0x7fffe8451d18, plen=0x7fffe8451d10,
is_write=false) at /home/build/src/qemu/git/qemu/exec.c:428
#3  0x000000000041a4be in address_space_read_full (as=0x1961600,
addr=3221225472, attrs=..., buf=0x7fffe8451f10 "\030(\226\001", len=8)
at /home/build/src/qemu/git/qemu/exec.c:2724
#4  0x000000000041a5b3 in address_space_read (len=8, buf=0x7fffe8451f10
"\030(\226\001", attrs=..., addr=3221225472, as=0x1961600) at
/home/build/src/qemu/git/qemu/include/exec/memory.h:1460
#5  address_space_rw (as=0x1961600, addr=3221225472, attrs=...,
buf=0x7fffe8451f10 "\030(\226\001", len=8, is_write=false) at
/home/build/src/qemu/git/qemu/exec.c:2739
#6  0x00000000005c71e0 in dma_memory_rw_relaxed (as=0x1961600,
addr=3221225472, buf=0x7fffe8451f10, len=8, dir=DMA_DIRECTION_TO_DEVICE)
at /home/build/src/qemu/git/qemu/include/sysemu/dma.h:87
#7  0x00000000005c7258 in dma_memory_rw (as=0x1961600, addr=3221225472,
buf=0x7fffe8451f10, len=8, dir=DMA_DIRECTION_TO_DEVICE) at
/home/build/src/qemu/git/qemu/include/sysemu/dma.h:110
#8  0x00000000005c72fa in pci_dma_rw (dev=0x19613f0, addr=3221225472,
buf=0x7fffe8451f10, len=8, dir=DMA_DIRECTION_TO_DEVICE) at
/home/build/src/qemu/git/qemu/include/hw/pci/pci.h:731
#9  0x00000000005c735a in pci_dma_read (dev=0x19613f0, addr=3221225472,
buf=0x7fffe8451f10, len=8) at
/home/build/src/qemu/git/qemu/include/hw/pci/pci.h:738
#10 0x00000000005c7980 in bmdma_rw_buf (dma=0x1962fa8, is_write=1) at
hw/ide/pci.c:139
#11 0x00000000005c4372 in ide_atapi_cmd_read_dma_cb (opaque=0x1962550,
ret=0) at hw/ide/atapi.c:413
#12 0x00000000005c7dfe in bmdma_cmd_writeb (bm=0x1962fa8, val=9) at
hw/ide/pci.c:245
#13 0x00000000005c91a9 in bmdma_write (opaque=0x1962fa8, addr=0, val=9,
size=1) at hw/ide/cmd646.c:219
#14 0x0000000000469fb8 in memory_region_write_accessor (mr=0x1963100,
addr=0, value=0x7fffe8452148, size=1, shift=0, mask=255, attrs=...) at
/home/build/src/qemu/git/qemu/memory.c:525
#15 0x000000000046a1e4 in access_with_adjusted_size (addr=0,
value=0x7fffe8452148, size=1, access_size_min=1, access_size_max=4,
access=0x469ec1 <memory_region_write_accessor>, mr=0x1963100, attrs=...)
    at /home/build/src/qemu/git/qemu/memory.c:586
#16 0x000000000046d42b in memory_region_dispatch_write (mr=0x1963100,
addr=0, data=9, size=1, attrs=...) at
/home/build/src/qemu/git/qemu/memory.c:1262
#17 0x000000000041a051 in address_space_write_continue (as=0x12bb4b0,
addr=2190466908936, attrs=..., buf=0x7fffe8452323 "\t\376\001", len=1,
addr1=0, l=1, mr=0x1963100) at /home/build/src/qemu/git/qemu/exec.c:2590
#18 0x000000000041a1c3 in address_space_write (as=0x12bb4b0,
addr=2190466908936, attrs=..., buf=0x7fffe8452323 "\t\376\001", len=1)
at /home/build/src/qemu/git/qemu/exec.c:2635
#19 0x000000000041a569 in address_space_rw (as=0x12bb4b0,
addr=2190466908936, attrs=..., buf=0x7fffe8452323 "\t\376\001", len=1,
is_write=true) at /home/build/src/qemu/git/qemu/exec.c:2737
#20 0x000000000041c27d in address_space_stb (as=0x12bb4b0,
addr=2190466908936, val=9, attrs=..., result=0x0) at
/home/build/src/qemu/git/qemu/exec.c:3477
#21 0x000000000041c2f5 in stb_phys (as=0x12bb4b0, addr=2190466908936,
val=9) at /home/build/src/qemu/git/qemu/exec.c:3485
#22 0x0000000000504759 in helper_st_asi (env=0x12d57e8,
addr=2190466908936, val=9, asi=29, size=1) at
/home/build/src/qemu/git/qemu/target-sparc/ldst_helper.c:1801
#23 0x00000000405bf4b0 in code_gen_buffer ()
#24 0x0000000000420c97 in cpu_tb_exec (cpu=0x12cd570,
itb=0x7fffe8fc10c0) at /home/build/src/qemu/git/qemu/cpu-exec.c:166
#25 0x0000000000421882 in cpu_loop_exec_tb (cpu=0x12cd570,
tb=0x7fffe8fc10c0, last_tb=0x7fffe8452988, tb_exit=0x7fffe8452984,
sc=0x7fffe84529a0) at /home/build/src/qemu/git/qemu/cpu-exec.c:530
#26 0x0000000000421b40 in cpu_exec (cpu=0x12cd570) at
/home/build/src/qemu/git/qemu/cpu-exec.c:626
#27 0x0000000000451e6b in tcg_cpu_exec (cpu=0x12cd570) at
/home/build/src/qemu/git/qemu/cpus.c:1541
#28 0x0000000000451f6d in tcg_exec_all () at
/home/build/src/qemu/git/qemu/cpus.c:1574
#29 0x00000000004510b4 in qemu_tcg_cpu_thread_fn (arg=0x12cd570) at
/home/build/src/qemu/git/qemu/cpus.c:1171
#30 0x00007ffff264bb50 in start_thread (arg=<optimized out>) at
pthread_create.c:304
#31 0x00007ffff2395fbd in clone () at
../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#32 0x0000000000000000 in ?? ()
(gdb)



ATB,

Mark.