Re: [RFC XEN PATCH v14 4/5] tools: Add new function to get gsi from dev

[Jan Beulich <jbeulich@xxxxxxxx>]

On 03.09.2024 17:51, Anthony PERARD wrote:
> On Tue, Sep 03, 2024 at 03:04:23PM +0800, Jiqian Chen wrote:
>> --- a/tools/libs/ctrl/xc_linux.c
>> +++ b/tools/libs/ctrl/xc_linux.c
>> @@ -66,6 +66,26 @@ void *xc_memalign(xc_interface *xch, size_t alignment, 
>> size_t size)
>>      return ptr;
>>  }
>>  
>> +int xc_pcidev_get_gsi(xc_interface *xch, uint32_t sbdf)
>> +{
>> +    int ret;
>> +    privcmd_pcidev_get_gsi_t dev_gsi = {
>> +        .sbdf = sbdf,
>> +        .gsi = 0,
>> +    };
>> +
>> +    ret = ioctl(xencall_fd(xch->xcall),
>> +                IOCTL_PRIVCMD_PCIDEV_GET_GSI, &dev_gsi);
>> +
>> +    if (ret < 0) {
>> +        PERROR("Failed to get gsi from dev");
>> +    } else {
>> +        ret = dev_gsi.gsi;
> 
> I've just notice that this is mixing signed and unsigned int.
> We are storing a "__u32" into an "int" here. This isn't great as we are
> throwing way lots of potentially good value. (Even if I have no idea if
> they are possible.)

GSIs are numbered 0...N-1, with N being the number of lines all IO-APICs
in the system together have. Surely that's not going to go into the
millions, let alone billions. At least not any time soon, and there's
move away from using line interrupts anyway.

Jan