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

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

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the screenshots in attachment shows:
1. this patch don`t affect the device realization.
2. also shows what that bug looks like, which is described in my 
previous patch: "bugfix: passing reference instead of value"

On 12/29/2015 04:46 PM, 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)"
>
> 2. snprintf() has tiny tiny chance to 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
>
> 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
>
>   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";
>   }
>
>

-- 
Yours Sincerely,

Cao Jin



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