Re: [Qemu-devel] [PATCH v6 2/4] ahci.c: Don't assume AHCIState's parent is AHCIPCIState

[John Snow <jsnow@redhat.com>]

On 08/28/2015 08:04 PM, Alistair Francis wrote:
> The AHCIState struct can either have AHCIPCIState or SysbusAHCIState
> 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 <alistair.francis@xilinx.com>
> ---
> V5:
>  - Remove the return checks when setting PCIDevice
> V4:
>  - Remove unnesicary casts
>  - Use object_dynamic_cast() instead of object_class_dynamic_cast()
> 
>  hw/ide/ahci.c |   13 +++++++------
>  hw/ide/ahci.h |    2 ++
>  2 files changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/hw/ide/ahci.c b/hw/ide/ahci.c
> index 02d85fa..d83efa4 100644
> --- a/hw/ide/ahci.c
> +++ b/hw/ide/ahci.c
> @@ -121,9 +121,9 @@ 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);
> +    DeviceState *dev_state = s->container;
> +    PCIDevice *pci_dev = (PCIDevice *) object_dynamic_cast(OBJECT(dev_state),
> +                                                           TYPE_PCI_DEVICE);
>  
>      DPRINTF(0, "raise irq\n");
>  
> @@ -136,9 +136,9 @@ 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 = s->container;
> +    PCIDevice *pci_dev = (PCIDevice *) object_dynamic_cast(OBJECT(dev_state),
> +                                                           TYPE_PCI_DEVICE);
>  
>      DPRINTF(0, "lower irq\n");
>  
> @@ -1436,6 +1436,7 @@ 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;
> 

This is kind of ugly ... but it works, and it doesn't impact migratability.

If someone abstracts MSI away from AHCI in the future, this can be
un-done and the state cleaned up again.

Doesn't break anything, so:
Acked-by: John Snow <jsnow@redhat.com>