On Tue, 30 Jun 2020 at 13:31, P J P wrote:
>
> From: Prasad J Pandit
>
> Add spapr msi mmio read method to avoid NULL pointer dereference
> issue.
>
> Reported-by: Lei Sun
> Acked-by: David Gibson
> Reviewed-by: Li Qiang
> Signed-off-by: Prasad J Pandit
> ---
> hw/ppc/spapr_pci.c | 13 +++--
> 1 file changed, 11 insertions(+), 2 deletions(-)
>
> Update v3: Add Acked-by: ...
> -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg08054.html
>
> 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
QEMU multiline comments should have the '/*' on a line of its own.
> + * define .read method to avoid assert failure in memory_region_init_io
> + */
If this is undefined behaviour per the PCI spec then LOG_UNIMP
is the wrong thing -- this should either be LOG_GUEST_ERROR
(if the guest can do this or program the h/w to do this)
or assert() (if the only way this could happen would be a bug
in a QEMU model of a PCI device).
> +.read = spapr_msi_read,
> .write = spapr_msi_write,
> .endianness = DEVICE_LITTLE_ENDIAN
> };
> --
> 2.26.2
thanks
-- PMM
