Re: [Qemu-devel] Fwd: [PATCH v2] Guest OS hangs on usb_add

[Anthony Liguori]

On 11/02/2010 09:51 AM, TJ wrote:
> Doesn't look like this has ever been committed. qemu-kvm-0.13 has just arrived
> to the portage tree, but I am still having problems with it. I checked the git
> log and it's not there! Please commit.
>    

One off device hacks are concerning because it's basically impossible to 
review.

Why does this work on bare metal?

Regards,

Anthony Liguori

> -TJ
>
> -------- Original Message --------
> Subject: [PATCH v2] Guest OS hangs on usb_add
> Date: Mon, 28 Jun 2010 10:47:03 -0400
> From: TJ<address@hidden>
> To: address@hidden<address@hidden>
> CC: Gianni Tedesco<address@hidden>
>
> This is a small patch to sligtly "intelligentify" usb device and
> config descriptor parsing and to handle bug with certain usb
> device (URC MX-950) reporting device desriptor length as 0x18
> instead of 18 with added vendor_id/product_id check
> ---
>   hw/usb.h    |    5 +++++
>   usb-linux.c |   37 ++++++++++++++++++++++---------------
>   2 files changed, 27 insertions(+), 15 deletions(-)
>
> diff --git a/hw/usb.h b/hw/usb.h
> index 00d2802..5c3528f 100644
> --- a/hw/usb.h
> +++ b/hw/usb.h
> @@ -117,6 +117,11 @@
>   #define USB_DT_INTERFACE              0x04
>   #define USB_DT_ENDPOINT                       0x05
>
> +#define USB_DT_DEVICE_LEN              18
> +#define USB_DT_CONFIG_LEN              9
> +#define USB_DT_INTERFACE_LEN           9
> +#define USB_DT_ENDPOINT_LEN            7
> +
>   #define USB_ENDPOINT_XFER_CONTROL     0
>   #define USB_ENDPOINT_XFER_ISOC                1
>   #define USB_ENDPOINT_XFER_BULK                2
> diff --git a/usb-linux.c b/usb-linux.c
> index 88273ff..2ac6562 100644
> --- a/usb-linux.c
> +++ b/usb-linux.c
> @@ -288,7 +288,7 @@ static void async_cancel(USBPacket *unused, void *opaque)
>
>   static int usb_host_claim_interfaces(USBHostDevice *dev, int configuration)
>   {
> -    int dev_descr_len, config_descr_len;
> +    int dev_descr_len, config_descr_total_len;
>       int interface, nb_interfaces;
>       int ret, i;
>
> @@ -297,32 +297,39 @@ static int usb_host_claim_interfaces(USBHostDevice *dev,
> int configuration)
>
>       DPRINTF("husb: claiming interfaces. config %d\n", configuration);
>
> -    i = 0;
>       dev_descr_len = dev->descr[0];
> -    if (dev_descr_len>  dev->descr_len) {
> +    if (dev_descr_len == 0x18&&  dev->descr[ 8] == 0x47&&  dev->descr[ 9] == 
> 0x46
> +&&  dev->descr[10] == 0x00&&  dev->descr[11] == 0x30)
> +        dev_descr_len = USB_DT_DEVICE_LEN; /* for buggy MX-950 remote reporting
> len in hex */
> +
> +    if (dev_descr_len>  dev->descr_len || dev_descr_len<  USB_DT_DEVICE_LEN ||
> dev->descr[1] != USB_DT_DEVICE) {
> +        fprintf(stderr, "husb: invalid device descriptor\n");
>           goto fail;
>       }
>
> -    i += dev_descr_len;
> -    while (i<  dev->descr_len) {
> +    for (i = dev_descr_len; i<  dev->descr_len; ) {
>           DPRINTF("husb: i is %d, descr_len is %d, dl %d, dt %d\n",
>                   i, dev->descr_len,
>                  dev->descr[i], dev->descr[i+1]);
>
> -        if (dev->descr[i+1] != USB_DT_CONFIG) {
> -            i += dev->descr[i];
> -            continue;
> +        if (dev->descr[i]<  2) {
> +            fprintf(stderr, "husb: invalid descriptor\n");
> +            goto fail;
>           }
> -        config_descr_len = dev->descr[i];
> +        if (dev->descr[i+1] == USB_DT_CONFIG) {
> +            config_descr_total_len = dev->descr[i+2] + (dev->descr[i+3]<<  8);
>
> -        printf("husb: config #%d need %d\n", dev->descr[i + 5], configuration);
> +            printf("husb: config #%d need %d\n", dev->descr[i + 5], 
> configuration);
>
> -        if (configuration<  0 || configuration == dev->descr[i + 5]) {
> -            configuration = dev->descr[i + 5];
> -            break;
> -        }
> +            if (configuration<  0 || configuration == dev->descr[i + 5]) {
> +                configuration = dev->descr[i + 5];
> +                break;
> +            }
>
> -        i += config_descr_len;
> +            i += config_descr_total_len;
> +        }
> +        else
> +            i += dev->descr[i];
>       }
>
>       if (i>= dev->descr_len) {
>
>
>