On Thu, Jun 25, 2020 at 12:25:20AM +0530, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
> 
> Add spapr msi mmio read method to avoid NULL pointer dereference
> issue.
> 
> Reported-by: Lei Sun <slei.casper@gmail.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>

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

> ---
>  hw/ppc/spapr_pci.c | 13 +++++++++++--
>  1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/ppc/spapr_pci.c b/hw/ppc/spapr_pci.c
> index 329002ac04..7033352834 100644
> --- a/hw/ppc/spapr_pci.c
> +++ b/hw/ppc/spapr_pci.c
> @@ -52,6 +52,7 @@
>  #include "sysemu/kvm.h"
>  #include "sysemu/hostmem.h"
>  #include "sysemu/numa.h"
> +#include "qemu/log.h"
>  
>  /* Copied from the kernel arch/powerpc/platforms/pseries/msi.c */
>  #define RTAS_QUERY_FN           0
> @@ -738,6 +739,12 @@ static PCIINTxRoute spapr_route_intx_pin_to_irq(void *opaque, int pin)
>      return route;
>  }
>  
> +static uint64_t spapr_msi_read(void *opaque, hwaddr addr, unsigned size)
> +{
> +    qemu_log_mask(LOG_UNIMP, "%s not implemented\n", __func__);
> +    return 0;
> +}
> +
>  /*
>   * MSI/MSIX memory region implementation.
>   * The handler handles both MSI and MSIX.
> @@ -755,8 +762,10 @@ static void spapr_msi_write(void *opaque, hwaddr addr,
>  }
>  
>  static const MemoryRegionOps spapr_msi_ops = {
> -    /* There is no .read as the read result is undefined by PCI spec */
> -    .read = NULL,
> +    /* .read result is undefined by PCI spec
> +     * define .read method to avoid assert failure in memory_region_init_io
> +     */
> +    .read = spapr_msi_read,
>      .write = spapr_msi_write,
>      .endianness = DEVICE_LITTLE_ENDIAN
>  };

-- 
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