Re: [Qemu-devel] [Qemu-ppc] [for-2.11 PATCH 06/26] spapr_pci: parent the MSI memory region to the PHB

[Alexey Kardashevskiy]

On 26/07/17 03:59, Greg Kurz wrote:
> This memory region should be owned by the PHB. This ensures the PHB
> cannot be finalized as long as the the region is guest visible, or
> used by a CPU or a device.

Out of curiosity - does it really ensure this? Passing a parent to
memory_region_init_io() adds a reference to a child (i.e. "msi" region),
not to the PHB object. It is probably a good thing to have an owner for
every MR anyway, I am just not sure about the commit log, what does not
work if you do not do this?


> 
> Signed-off-by: Greg Kurz <address@hidden>
> ---
>  hw/ppc/spapr_pci.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 3fe7f3145467..4e4165b44b9a 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -1703,7 +1703,7 @@ static void spapr_phb_realize(DeviceState *dev, Error 
> **errp)
>      }
>  #endif
>  
> -    memory_region_init_io(&sphb->msiwindow, NULL, &spapr_msi_ops, spapr,
> +    memory_region_init_io(&sphb->msiwindow, OBJECT(sphb), &spapr_msi_ops, 
> spapr,
>                            "msi", msi_window_size);
>      memory_region_add_subregion(&sphb->iommu_root, SPAPR_PCI_MSI_WINDOW,
>                                  &sphb->msiwindow);
> 
> 


-- 
Alexey