Re: [Qemu-devel] [PATCH v4] igd-passthrough-i440FX: convert to realize()

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

Agree with your review point. Since can`t get contact with author 
tiejun.chen@intel.com, maybe only can ask for test help from Stefano, I 
will send next version when we get in touch with stefano.

On 12/29/2015 07:25 PM, Michael S. Tsirkin wrote:
> On Tue, Dec 29, 2015 at 04:46:03PM +0800, Cao jin wrote:
>> Signed-off-by: Cao jin <caoj.fnst@cn.fujitsu.com>
>> ---
>> changelog v4:
>> 1. strip the bugfix code, but I guess this patch should be applied after
>>     that bugfix patch.
>> 2. Other little fix as per previous review
>>
>> Some explanation to previous review:
>> 1. error_setg_errno() I use in this patch will print the strerror(errno), so I
>>     guess it will be informative enough? example:
>>
>>     error_setg_errno(errp, errno, "open %s fail", path); will print:
>>     "open bluhbluh fail: string_from_strerrer(errno)"
>
> I'd prefer some mention of why this is attempted too.
> E.g. "igd passthrough : open bluhbluh fail"
>
>> 2. snprintf() has tiny tiny chance to fail,
>
> It just formats a string into a buffer. the buffer
> is pre-allocated, and we know it's large enough for the data.
> How can it fail?
>
>
>> I don`t assert here, because this
>>     device is on-board, it init during machine initialization, in case it fails,
>>     the errp we set will results in error_report(err) and exit(1), at least can
>>     let user know why fail. see the call-chain:
>>
>>     pc_xen_hvm_init_pci->pc_init1->i440fx_init->pci_create_simple-> pci_create_simple_multifunction->qdev_init_nofail
>
> unlike open failing, there's nothing user can do, this means there's
> a coding bug somewhere, and assert is easier to debug.
>
>> About test:
>> 1. Compiled
>> 2. Did a dirty hack to force create/realize this device in pc_init1(), prove
>>     that the realizing process is ok, I will reply this mail later to attch the
>>     screenshot evidence
>
> Good job, thanks!
> You should also Cc Tiejun Chen <tiejun.chen@intel.com> who wrote this
> code, presumably with access to hardware to test on.
>
>
>>   hw/pci-host/piix.c | 30 +++++++++++++++---------------
>>   1 file changed, 15 insertions(+), 15 deletions(-)
>>
>> diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
>> index a9cb983..e91570f 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 void host_pci_config_read(int pos, int len, uint32_t *val, Error **errp)
>>   {
>>       char path[PATH_MAX];
>>       int config_fd;
>> @@ -769,19 +769,19 @@ static int host_pci_config_read(int pos, int len, uint32_t *val)
>>       /* Access real host bridge. */
>>       int rc = snprintf(path, size, "/sys/bus/pci/devices/%04x:%02x:%02x.%d/%s",
>>                         0, 0, 0, 0, "config");
>> -    int ret = 0;
>>
>>       if (rc >= size || rc < 0) {
>> -        return -ENODEV;
>> +        error_setg_errno(errp, errno, "snprintf err");
>>       }
>>
>>       config_fd = open(path, O_RDWR);
>>       if (config_fd < 0) {
>> -        return -ENODEV;
>> +        error_setg_errno(errp, errno, "open %s fail", path);
>> +        return;
>>       }
>>
>>       if (lseek(config_fd, pos, SEEK_SET) != pos) {
>> -        ret = -errno;
>> +        error_setg_errno(errp, errno, "lseek err");
>>           goto out;
>>       }
>>
>> @@ -789,32 +789,32 @@ static int host_pci_config_read(int pos, int len, uint32_t *val)
>>           rc = read(config_fd, (uint8_t *)val, len);
>>       } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
>>       if (rc != len) {
>> -        ret = -errno;
>> +        error_setg_errno(errp, errno, "read err");
>>       }
>>
>>   out:
>>       close(config_fd);
>> -    return ret;
>>   }
>>
>> -static int igd_pt_i440fx_initfn(struct PCIDevice *pci_dev)
>> +static void igd_pt_i440fx_realize(struct PCIDevice *pci_dev, Error **errp)
>>   {
>>       uint32_t val = 0;
>> -    int rc, i, num;
>> +    int i, num;
>>       int pos, len;
>> +    Error *local_err = NULL;
>>
>>       num = ARRAY_SIZE(igd_host_bridge_infos);
>>       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);
>> -        if (rc) {
>> -            return -ENODEV;
>> +
>> +        host_pci_config_read(pos, len, &val, &local_err);
>> +        if (local_err) {
>> +            error_propagate(errp, local_err);
>> +            return;
>>           }
>>           pci_default_write_config(pci_dev, pos, cpu_to_le32(val), len);
>>       }
>> -
>> -    return 0;
>>   }
>>
>>   static void igd_passthrough_i440fx_class_init(ObjectClass *klass, void *data)
>> @@ -822,7 +822,7 @@ static void igd_passthrough_i440fx_class_init(ObjectClass *klass, void *data)
>>       DeviceClass *dc = DEVICE_CLASS(klass);
>>       PCIDeviceClass *k = PCI_DEVICE_CLASS(klass);
>>
>> -    k->init = igd_pt_i440fx_initfn;
>> +    k->realize = igd_pt_i440fx_realize;
>>       dc->desc = "IGD Passthrough Host bridge";
>>   }
>>
>> --
>> 2.1.0
>>
>>
>
>
> .
>

-- 
Yours Sincerely,

Cao Jin