Re: [Qemu-devel] [PATCH 20/39] virtio-pci: convert to memory API

[Anthony Liguori]

On 08/01/2011 03:26 AM, Michael S. Tsirkin wrote:
> On Sun, Jul 31, 2011 at 08:57:43PM +0300, Avi Kivity wrote:
> > @@ -491,30 +473,26 @@ static void virtio_pci_config_writel(void *opaque, 
> > uint32_t addr, uint32_t val)
> >       virtio_config_writel(proxy->vdev, addr, val);
> >   }
> >
> > -static void virtio_map(PCIDevice *pci_dev, int region_num,
> > -                       pcibus_t addr, pcibus_t size, int type)
> > -{
> > -    VirtIOPCIProxy *proxy = container_of(pci_dev, VirtIOPCIProxy, pci_dev);
> > -    VirtIODevice *vdev = proxy->vdev;
> > -    unsigned config_len = VIRTIO_PCI_REGION_SIZE(pci_dev) + vdev->config_len;
> > -
> > -    proxy->addr = addr;
> > -
> > -    register_ioport_write(addr, config_len, 1, virtio_pci_config_writeb, 
> > proxy);
> > -    register_ioport_write(addr, config_len, 2, virtio_pci_config_writew, 
> > proxy);
> > -    register_ioport_write(addr, config_len, 4, virtio_pci_config_writel, 
> > proxy);
> > -    register_ioport_read(addr, config_len, 1, virtio_pci_config_readb, proxy);
> > -    register_ioport_read(addr, config_len, 2, virtio_pci_config_readw, proxy);
> > -    register_ioport_read(addr, config_len, 4, virtio_pci_config_readl, proxy);
> > +const MemoryRegionPortio virtio_portio[] = {
> > +    { 0, 0x10000, 1, .write = virtio_pci_config_writeb, },
> > +    { 0, 0x10000, 2, .write = virtio_pci_config_writew, },
> > +    { 0, 0x10000, 4, .write = virtio_pci_config_writel, },
> > +    { 0, 0x10000, 1, .read = virtio_pci_config_readb, },
> > +    { 0, 0x10000, 2, .read = virtio_pci_config_readw, },
> > +    { 0, 0x10000, 4, .read = virtio_pci_config_readl, },
> > +    PORTIO_END
> > +};
> >
> > -    if (vdev->config_len)
> > -        vdev->get_config(vdev, vdev->config);
> > -}
> > +static const MemoryRegionOps virtio_pci_config_ops = {
> > +    .old_portio = virtio_portio,
> > +    .endianness = DEVICE_LITTLE_ENDIAN,
> > +};
> >
> >   static void virtio_write_config(PCIDevice *pci_dev, uint32_t address,
> >                                   uint32_t val, int len)
> >   {
> >       VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
> > +    VirtIODevice *vdev = proxy->vdev;
> >
> >       if (PCI_COMMAND == address) {
> >           if (!(val&  PCI_COMMAND_MASTER)) {
> > @@ -525,6 +503,9 @@ static void virtio_write_config(PCIDevice *pci_dev, 
> > uint32_t address,
> >               }
> >           }
> >       }
> > +    if (address == PCI_BASE_ADDRESS_0&&  vdev->config_len) {
> > +        vdev->get_config(vdev, vdev->config);
> > +    }
> >
> >       pci_default_write_config(pci_dev, address, val, len);
> >       msix_write_config(pci_dev, address, val, len);
>
> I'm not really sure why did we get the config on map,
> specifically - Anthony, do you know?

It's just a mechanism to lazily load the config.  We could just as 
easily read the config whenever the (virtio) config space was accessed.

Regards,

Anthony Liguori

> But if we want to do that, memory space enable might
> be a better place. Or maybe we just want a callback on
> map.