[RFC] vDPA: Trying to make sense of config data

[RFC] vDPA: Trying to make sense of config data

[Carlos Bilbao]

Hello folks,

I'm using the code below to retrieve configuration data for my vDPA file
via ioctl. I get as output:

Configuration data (24 bytes):
5a c3 5f 68 48 a9 01 00 08 00 dc 05 00 00 00 00
00 00 00 00 00 00 00 00
ASCII representation:
Z._hH...................

Could a good Samaritan point me in the right direction for the docs I need
to understand these values and convert them to a human-readable format?
hank you in advance!

Regards,
Carlos

---

void check_config(int fd) {

    uint32_t size;
    struct vhost_vdpa_config *config;
    uint8_t *buf;

    if (ioctl(fd, VHOST_VDPA_GET_CONFIG_SIZE, &size) < 0) {
        perror("ioctl failed");
        return;
    }

    config = malloc(sizeof(struct vhost_vdpa_config) + size);
    if (!config) {
        perror("malloc failed");
        return;
    }

    memset(config, 0, sizeof(struct vhost_vdpa_config) + size);
    config->len = size;
    config->off = 0;

    buf = config->buf;

    if (ioctl(fd, VHOST_VDPA_GET_CONFIG, config) < 0) {
        perror("ioctl failed");
    } else {
        printf("Configuration data (%u bytes):\n", size);

        /* Print the data in a human-readable format */
        for (unsigned int i = 0; i < size; i++) {
            if (i % 16 == 0 && i != 0) printf("\n");
            printf("%02x ", buf[i]);
        }
        printf("\n");

        printf("ASCII representation:\n");
        for (unsigned int i = 0; i < size; i++) {
            if (buf[i] >= 32 && buf[i] <= 126) {
                printf("%c", buf[i]);
            } else {
                printf(".");
            }
        }
        printf("\n");
    }

    free(config);
}

Re: [RFC] vDPA: Trying to make sense of config data

[Carlos Bilbao]

Hello again, 

Answering my own question:

https://elixir.bootlin.com/linux/v6.10.2/source/include/uapi/linux/virtio_net.h#L92

Thanks, Carlos

On 8/22/24 1:21 PM, Carlos Bilbao wrote:
> Hello folks,
>
> I'm using the code below to retrieve configuration data for my vDPA file
> via ioctl. I get as output:
>
> Configuration data (24 bytes):
> 5a c3 5f 68 48 a9 01 00 08 00 dc 05 00 00 00 00
> 00 00 00 00 00 00 00 00
> ASCII representation:
> Z._hH...................
>
> Could a good Samaritan point me in the right direction for the docs I need
> to understand these values and convert them to a human-readable format?
> hank you in advance!
>
> Regards,
> Carlos
>
> ---
>
> void check_config(int fd) {
>
>     uint32_t size;
>     struct vhost_vdpa_config *config;
>     uint8_t *buf;
>
>     if (ioctl(fd, VHOST_VDPA_GET_CONFIG_SIZE, &size) < 0) {
>         perror("ioctl failed");
>         return;
>     }
>
>     config = malloc(sizeof(struct vhost_vdpa_config) + size);
>     if (!config) {
>         perror("malloc failed");
>         return;
>     }
>
>     memset(config, 0, sizeof(struct vhost_vdpa_config) + size);
>     config->len = size;
>     config->off = 0;
>
>     buf = config->buf;
>
>     if (ioctl(fd, VHOST_VDPA_GET_CONFIG, config) < 0) {
>         perror("ioctl failed");
>     } else {
>         printf("Configuration data (%u bytes):\n", size);
>
>         /* Print the data in a human-readable format */
>         for (unsigned int i = 0; i < size; i++) {
>             if (i % 16 == 0 && i != 0) printf("\n");
>             printf("%02x ", buf[i]);
>         }
>         printf("\n");
>
>         printf("ASCII representation:\n");
>         for (unsigned int i = 0; i < size; i++) {
>             if (buf[i] >= 32 && buf[i] <= 126) {
>                 printf("%c", buf[i]);
>             } else {
>                 printf(".");
>             }
>         }
>         printf("\n");
>     }
>
>     free(config);
> }

Re: [RFC] vDPA: Trying to make sense of config data

[Michael S. Tsirkin]

On Fri, Aug 23, 2024 at 09:51:24AM -0500, Carlos Bilbao wrote:
> Hello again, 
> 
> Answering my own question:
> 
> https://elixir.bootlin.com/linux/v6.10.2/source/include/uapi/linux/virtio_net.h#L92
> 
> Thanks, Carlos

Right. kernel.org would be the official source for that header.
Or if you want it in english, that would be the virtio spec.

-- 
MST