Re: [Qemu-devel] [PATCH v3 2/4] ahci.c: Don't assume AHCIState's parent is AHCIPCIState

[Peter Crosthwaite]

On Thu, Aug 27, 2015 at 3:06 PM, Alistair Francis
<address@hidden> wrote:
> On Thu, Aug 27, 2015 at 2:28 PM, Peter Crosthwaite
> <address@hidden> wrote:
>> On Thu, Aug 27, 2015 at 1:47 PM, Alistair Francis
>> <address@hidden> wrote:
>>> The AHCIState strucut can either have AHCIPCIState or SysbusAHCIState
>>
>> "struct"
>
> Good catch, will fix
>
>>
>>> as a parent. The ahci_irq_lower() and ahci_irq_raise() functions
>>> assume that it is always AHCIPCIState, which is not always the
>>> case, which causes a seg fault. Verify what the container of AHCIState
>>> is before setting the PCIDevice struct.
>>>
>>> Signed-off-by: Alistair Francis <address@hidden>
>>> ---
>>>
>>>  hw/ide/ahci.c |   29 +++++++++++++++++++++++------
>>>  hw/ide/ahci.h |    2 ++
>>>  2 files changed, 25 insertions(+), 6 deletions(-)
>>>
>>> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
>>> index 02d85fa..b45b21d 100644
>>> --- a/hw/ide/ahci.c
>>> +++ b/hw/ide/ahci.c
>>> @@ -121,9 +121,17 @@ static uint32_t  ahci_port_read(AHCIState *s, int 
>>> port, int offset)
>>>
>>>  static void ahci_irq_raise(AHCIState *s, AHCIDevice *dev)
>>>  {
>>> -    AHCIPCIState *d = container_of(s, AHCIPCIState, ahci);
>>> -    PCIDevice *pci_dev =
>>> -        (PCIDevice *)object_dynamic_cast(OBJECT(d), TYPE_PCI_DEVICE);
>>
>> Why can't you just convert this to use use s->container? ...
>>
>>> +    DeviceState *dev_state = DEVICE(s->container);
>>
>> Unneeded cast. s->container is already DeviceState, but I'm not sure
>> you need this local variable at all.
>
> I'll remove the cast. The variable is just included to save line space
> (and complexity).
>
>>
>>> +    PCIDevice *pci_dev = NULL;
>>> +    ObjectClass *ret;
>>> +
>>> +    /* Check is AHCIState's parent is SysbusAHCIState or AHCIPCIState */
>>> +    ret = object_class_dynamic_cast(object_get_class(OBJECT(dev_state)),
>>> +                                    TYPE_PCI_DEVICE);
>>
>> ... I don't understand why this needs to be done as a class cast, does
>> the original object cast approach not work?
>
> The problem with the standard ones is that they contain asserts. So you can't
> do a test to see if the cast is possible, which is what I want to do.
>

But the original code uses object_dynamic_cast which should be a
non-asserting cast attempt. What was the assertion you were getting?

Regards,
Peter

> Thanks,
>
> Alistair
>
>>
>> Regards,
>> Peter
>>
>>> +    if (ret) {
>>> +        /* AHCIState parent is AHCIPCIState */
>>> +        pci_dev = PCI_DEVICE(dev_state);
>>> +    }
>>>
>>>      DPRINTF(0, "raise irq\n");
>>>
>>> @@ -136,9 +144,17 @@ static void ahci_irq_raise(AHCIState *s, AHCIDevice 
>>> *dev)
>>>
>>>  static void ahci_irq_lower(AHCIState *s, AHCIDevice *dev)
>>>  {
>>> -    AHCIPCIState *d = container_of(s, AHCIPCIState, ahci);
>>> -    PCIDevice *pci_dev =
>>> -        (PCIDevice *)object_dynamic_cast(OBJECT(d), TYPE_PCI_DEVICE);
>>> +    DeviceState *dev_state = DEVICE(s->container);
>>> +    PCIDevice *pci_dev = NULL;
>>> +    ObjectClass *ret;
>>> +
>>> +    /* Check is AHCIState's parent is SysbusAHCIState or AHCIPCIState */
>>> +    ret = object_class_dynamic_cast(object_get_class(OBJECT(dev_state)),
>>> +                                    TYPE_PCI_DEVICE);
>>> +    if (ret) {
>>> +        /* AHCIState parent is AHCIPCIState */
>>> +        pci_dev = PCI_DEVICE(dev_state);
>>> +    }
>>>
>>>      DPRINTF(0, "lower irq\n");
>>>
>>> @@ -1436,6 +1452,7 @@ void ahci_init(AHCIState *s, DeviceState *qdev, 
>>> AddressSpace *as, int ports)
>>>      s->as = as;
>>>      s->ports = ports;
>>>      s->dev = g_new0(AHCIDevice, ports);
>>> +    s->container = qdev;
>>>      ahci_reg_init(s);
>>>      /* XXX BAR size should be 1k, but that breaks, so bump it to 4k for 
>>> now */
>>>      memory_region_init_io(&s->mem, OBJECT(qdev), &ahci_mem_ops, s,
>>> diff --git a/hw/ide/ahci.h b/hw/ide/ahci.h
>>> index c055d6b..c9b3805 100644
>>> --- a/hw/ide/ahci.h
>>> +++ b/hw/ide/ahci.h
>>> @@ -287,6 +287,8 @@ struct AHCIDevice {
>>>  };
>>>
>>>  typedef struct AHCIState {
>>> +    DeviceState *container;
>>> +
>>>      AHCIDevice *dev;
>>>      AHCIControlRegs control_regs;
>>>      MemoryRegion mem;
>>> --
>>> 1.7.1
>>>
>>