Re: [PATCH v3 07/12] vfio-user: handle PCI config space accesses

[Stefan Hajnoczi]

On Mon, Oct 11, 2021 at 01:31:12AM -0400, Jagannathan Raman wrote:
> +static ssize_t vfu_object_cfg_access(vfu_ctx_t *vfu_ctx, char * const buf,
> +                                     size_t count, loff_t offset,
> +                                     const bool is_write)
> +{
> +    VfuObject *o = vfu_get_private(vfu_ctx);
> +    uint32_t pci_access_width = sizeof(uint32_t);
> +    size_t bytes = count;
> +    uint32_t val = 0;
> +    char *ptr = buf;
> +    int len;
> +
> +    while (bytes > 0) {
> +        len = (bytes > pci_access_width) ? pci_access_width : bytes;
> +        if (is_write) {
> +            memcpy(&val, ptr, len);
> +            pci_host_config_write_common(o->pci_dev, offset,
> +                                         pci_config_size(o->pci_dev),
> +                                         val, len);
> +            trace_vfu_cfg_write(offset, val);
> +        } else {
> +            val = pci_host_config_read_common(o->pci_dev, offset,
> +                                              pci_config_size(o->pci_dev), 
> len);
> +            memcpy(ptr, &val, len);
> +            trace_vfu_cfg_read(offset, val);
> +        }

pci_host_config_read/write_common() work with host-endian values. What
is the endianness of buf?

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