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

[Paolo Bonzini <pbonzini@redhat.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.

This patch works but the added conversion to LE is conceptually wrong.
The conversion from LE to CPU and vice versa is already done by
host_pci_config_read and pci_default_write_config.  You don't have it in
host_pci_config_read because the code is not portable and x86 is
little-endian.

Generally, functions that accept/return integers take care themselves of
endianness conversions.

Paolo


>>>   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;
>>>
>>
>