On Thu, Sep 07, 2023 at 06:04:10AM -0700, Mattias Nissler wrote: > PCI config space is little-endian, so on a big-endian host we need to > perform byte swaps for values as they are passed to and received from > the generic PCI config space access machinery.
Byteswapping only works when registers are accessed with their natural size, even with this patch. If there is something like a PCI Capability structure, then it needs to be read one register at a time to get back valid data. It cannot simply be copied in a single multi-DWORD access. I'm not sure if this fix is sufficient. Maybe pci_host_*() needs to be extended to support little-endian accesses instead? > > Signed-off-by: Mattias Nissler <mniss...@rivosinc.com> > --- > hw/remote/vfio-user-obj.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/hw/remote/vfio-user-obj.c b/hw/remote/vfio-user-obj.c > index cee5e615a9..d38b4700f3 100644 > --- a/hw/remote/vfio-user-obj.c > +++ b/hw/remote/vfio-user-obj.c > @@ -281,7 +281,7 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, > char * const buf, > while (bytes > 0) { > len = (bytes > pci_access_width) ? pci_access_width : bytes; > if (is_write) { > - memcpy(&val, ptr, len); > + val = ldn_le_p(ptr, len); > pci_host_config_write_common(o->pci_dev, offset, > pci_config_size(o->pci_dev), > val, len); > @@ -289,7 +289,7 @@ static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, > char * const buf, > } else { > val = pci_host_config_read_common(o->pci_dev, offset, > pci_config_size(o->pci_dev), > len); > - memcpy(ptr, &val, len); > + stn_le_p(ptr, len, val); > trace_vfu_cfg_read(offset, val); > } > offset += len; > -- > 2.34.1 >
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