On Thu, Jul 02, 2015 at 08:48:14PM +0200, Paolo Bonzini wrote:
>
>
> On 02/07/2015 15:00, Michael S. Tsirkin wrote:
> > + cfg = (void *)(proxy->pci_dev.config + proxy->config_cap);
> > + off = le32_to_cpu(cfg->cap.offset);
> > + len = le32_to_cpu(cfg->cap.length);
> > +
> > + if ((len == 1 || len == 2 || len == 4)) {
> > + address_space_write(&proxy->modern_as, off,
> > + MEMTXATTRS_UNSPECIFIED,
> > + cfg->pci_cfg_data, len);
> > + }
>
> This parses pci_cfg_data in target endianness I think. You just want to
> move the little-endian value from the config cap to the little-endian
> value in the modern_as, so you need to use ldl_le_p and
> address_space_stl_le.
but isn't that two byteswaps? why isn't this same as memcpy?
> > + }
> > +}
> > +
> > +static uint32_t virtio_read_config(PCIDevice *pci_dev,
> > + uint32_t address, int len)
> > +{
> > + VirtIOPCIProxy *proxy = DO_UPCAST(VirtIOPCIProxy, pci_dev, pci_dev);
> > + struct virtio_pci_cfg_cap *cfg;
> > +
> > + if (proxy->config_cap &&
> > + ranges_overlap(address, len, proxy->config_cap + offsetof(struct
> > virtio_pci_cfg_cap,
> > +
> > pci_cfg_data),
> > + sizeof cfg->pci_cfg_data)) {
> > + uint32_t off;
> > + uint32_t len;
> > +
> > + cfg = (void *)(proxy->pci_dev.config + proxy->config_cap);
> > + off = le32_to_cpu(cfg->cap.offset);
> > + len = le32_to_cpu(cfg->cap.length);
> > +
> > + if ((len == 1 || len == 2 || len == 4)) {
> > + address_space_read(&proxy->modern_as, off,
> > + MEMTXATTRS_UNSPECIFIED,
> > + cfg->pci_cfg_data, len);
>
> Same here, use address_space_ldl_le to read into an int, and stl_le_p to
> write into cfg->pci_cfg_data.
>
> The best way to check it, of course, is to write a unit test! :) But
> you could also use a Linux BE guest on LE host.
>
> Everything else looks good.
>
> Paolo
