Re: [Qemu-devel] [PATCH qemu v14 03/18] spapr_pci: Move DMA window enablement to a helper

[David Gibson <david@gibson.dropbear.id.au>]

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On Mon, Mar 21, 2016 at 06:46:51PM +1100, Alexey Kardashevskiy wrote:
> We are going to have multiple DMA windows soon so let's start preparing.
> 
> This adds a new helper to create a DMA window and makes use of it in
> sPAPRPHBState::realize().
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Reviewed-by: David Gibson <david@gibson.dropbear.id.au>

With one tweak..

> ---
> Changes:
> v14:
> * replaced "int" return to Error* in spapr_phb_dma_window_enable()
> ---
>  hw/ppc/spapr_pci.c | 47 ++++++++++++++++++++++++++++++++++-------------
>  1 file changed, 34 insertions(+), 13 deletions(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 79baa7b..18332bf 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -803,6 +803,33 @@ static char *spapr_phb_get_loc_code(sPAPRPHBState *sphb, PCIDevice *pdev)
>      return buf;
>  }
>  
> +static void spapr_phb_dma_window_enable(sPAPRPHBState *sphb,
> +                                       uint32_t liobn,
> +                                       uint32_t page_shift,
> +                                       uint64_t window_addr,
> +                                       uint64_t window_size,
> +                                       Error **errp)
> +{
> +    sPAPRTCETable *tcet;
> +    uint32_t nb_table = window_size >> page_shift;
> +
> +    if (!nb_table) {
> +        error_setg(errp, "Zero size table");
> +        return;
> +    }
> +
> +    tcet = spapr_tce_new_table(DEVICE(sphb), liobn, window_addr,
> +                               page_shift, nb_table, false);
> +    if (!tcet) {
> +        error_setg(errp, "Unable to create TCE table liobn %x for %s",
> +                   liobn, sphb->dtbusname);
> +        return;
> +    }
> +
> +    memory_region_add_subregion(&sphb->iommu_root, tcet->bus_offset,
> +                                spapr_tce_get_iommu(tcet));
> +}
> +
>  /* Macros to operate with address in OF binding to PCI */
>  #define b_x(x, p, l)    (((x) & ((1<<(l))-1)) << (p))
>  #define b_n(x)          b_x((x), 31, 1) /* 0 if relocatable */
> @@ -1307,8 +1334,7 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>      int i;
>      PCIBus *bus;
>      uint64_t msi_window_size = 4096;
> -    sPAPRTCETable *tcet;
> -    uint32_t nb_table;
> +    Error *local_err = NULL;
>  
>      if (sphb->index != (uint32_t)-1) {
>          hwaddr windows_base;
> @@ -1460,18 +1486,13 @@ static void spapr_phb_realize(DeviceState *dev, Error **errp)
>          }
>      }
>  
> -    nb_table = sphb->dma_win_size >> SPAPR_TCE_PAGE_SHIFT;
> -    tcet = spapr_tce_new_table(DEVICE(sphb), sphb->dma_liobn,
> -                               0, SPAPR_TCE_PAGE_SHIFT, nb_table, false);
> -    if (!tcet) {
> -        error_setg(errp, "Unable to create TCE table for %s",
> -                   sphb->dtbusname);
> -        return;
> -    }
> -
>      /* Register default 32bit DMA window */
> -    memory_region_add_subregion(&sphb->iommu_root, sphb->dma_win_addr,
> -                                spapr_tce_get_iommu(tcet));
> +    spapr_phb_dma_window_enable(sphb, sphb->dma_liobn, SPAPR_TCE_PAGE_SHIFT,
> +                                sphb->dma_win_addr, sphb->dma_win_size,
> +                                &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);

Should be a return; here so we don't continue if there's an error.

Actually.. that's not really right, we should be cleaning up all setup
we've done already on the failure path.  Without that I think we'll
leak some objects on a failed device_add.

But.. there are already a bunch of cases here that will do that, so we
can clean that up separately.  Probably the sanest way would be to add
an unrealize function() that can handle a partially realized object
and make sure it's called on all the error paths.

> +    }
>  
>      sphb->msi = g_hash_table_new_full(g_int_hash, g_int_equal, g_free, g_free);
>  }

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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