Re: [Qemu-devel] [PATCH v2] bugfix: passing reference instead of value

[Cao jin <caoj.fnst@cn.fujitsu.com>]

CC the code author: Tiejun Chen <tiejun.chen@intel.com>

On 12/28/2015 12:42 PM, Cao jin wrote:
> Fix the bug introduced by 595a4f07: Function host_pci_config_read() should be
> passed by a reference, not a value, for the later pci_default_write_config().
> And because value in PCI config space are little-endian, use cpu_to_le32() to
> ensure it when write config.
>
> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
> ---
> Separated from previous "igd-passthru convert to realize" patch. Since these
> two don`t have dependency, can send it solely.
>
> Not test since it is easy to find out if reading carefully, just compiled.
>
>   hw/pci-host/piix.c | 10 ++++++----
>   1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
> index 715208b..a9cb983 100644
> --- a/hw/pci-host/piix.c
> +++ b/hw/pci-host/piix.c
> @@ -761,7 +761,7 @@ static const IGDHostInfo igd_host_bridge_infos[] = {
>       {0xa8, 4},  /* SNB: base of GTT stolen memory */
>   };
>
> -static int host_pci_config_read(int pos, int len, uint32_t val)
> +static int host_pci_config_read(int pos, int len, uint32_t *val)
>   {
>       char path[PATH_MAX];
>       int config_fd;
> @@ -784,12 +784,14 @@ static int host_pci_config_read(int pos, int len, uint32_t val)
>           ret = -errno;
>           goto out;
>       }
> +
>       do {
> -        rc = read(config_fd, (uint8_t *)&val, len);
> +        rc = read(config_fd, (uint8_t *)val, len);
>       } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
>       if (rc != len) {
>           ret = -errno;
>       }
> +
>   out:
>       close(config_fd);
>       return ret;
> @@ -805,11 +807,11 @@ static int igd_pt_i440fx_initfn(struct PCIDevice *pci_dev)
>       for (i = 0; i < num; i++) {
>           pos = igd_host_bridge_infos[i].offset;
>           len = igd_host_bridge_infos[i].len;
> -        rc = host_pci_config_read(pos, len, val);
> +        rc = host_pci_config_read(pos, len, &val);
>           if (rc) {
>               return -ENODEV;
>           }
> -        pci_default_write_config(pci_dev, pos, val, len);
> +        pci_default_write_config(pci_dev, pos, cpu_to_le32(val), len);
>       }
>
>       return 0;
>

-- 
Yours Sincerely,

Cao Jin