Re: [Qemu-devel] [PULL 01/12] pci: Use bus master address space for delivering MSI/MSI-X messages

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Aug 14, 2014 at 06:08:44PM +0200, Michael S. Tsirkin wrote:
> From: Jan Kiszka <jan.kiszka@siemens.com>
> 
> The spec says (and real HW confirms this) that, if the bus master bit
> is 0, the device will not generate any PCI accesses. MSI and MSI-X
> messages fall among these, so we should use the corresponding address
> space to deliver them. This will prevent delivery if bus master support
> is disabled.
> 
> Cc: qemu-stable@nongnu.org

This is reported to break old guests which incorrectly don't enable
bus mastering.

Worth fixing (virtio needs a work-around) but please drop the patch from qemu-stable.

Thanks!

> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> ---
>  hw/pci/msi.c  | 2 +-
>  hw/pci/msix.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/pci/msi.c b/hw/pci/msi.c
> index a4a3040..52d2313 100644
> --- a/hw/pci/msi.c
> +++ b/hw/pci/msi.c
> @@ -291,7 +291,7 @@ void msi_notify(PCIDevice *dev, unsigned int vector)
>                     "notify vector 0x%x"
>                     " address: 0x%"PRIx64" data: 0x%"PRIx32"\n",
>                     vector, msg.address, msg.data);
> -    stl_le_phys(&address_space_memory, msg.address, msg.data);
> +    stl_le_phys(&dev->bus_master_as, msg.address, msg.data);
>  }
>  
>  /* Normally called by pci_default_write_config(). */
> diff --git a/hw/pci/msix.c b/hw/pci/msix.c
> index 5c49bfc..20ae476 100644
> --- a/hw/pci/msix.c
> +++ b/hw/pci/msix.c
> @@ -439,7 +439,7 @@ void msix_notify(PCIDevice *dev, unsigned vector)
>  
>      msg = msix_get_message(dev, vector);
>  
> -    stl_le_phys(&address_space_memory, msg.address, msg.data);
> +    stl_le_phys(&dev->bus_master_as, msg.address, msg.data);
>  }
>  
>  void msix_reset(PCIDevice *dev)
> -- 
> MST
>