lkml.org 
[lkml]   [2022]   [Jan]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/2] IB/rdmavt: modify rdmavt/qp.c for UML
From
Date


On 04/01/2022 01:00, Randy Dunlap wrote:
>
>
> On 1/3/22 15:04, Jason Gunthorpe wrote:
>> On Sat, Jan 01, 2022 at 11:06:23PM -0800, Randy Dunlap wrote:
>>> When building rdmavt for ARCH=um, qp.c has a build error on a reference
>>> to the x86-specific cpuinfo field 'x86_cache_size'. This value is then
>>> used to determine whether to use cacheless_memcpy() or not.
>>> Provide a fake value to LLC for CONFIG_UML. Then provide a separate
>>> verison of cacheless_memcpy() for CONFIG_UML that is just a plain
>>> memcpy(), like the calling code uses.
>>>
>>> Prevents these build errors:
>>>
>>> ../drivers/infiniband/sw/rdmavt/qp.c: In function ‘rvt_wss_llc_size’:
>>> ../drivers/infiniband/sw/rdmavt/qp.c:88:23: error: ‘struct cpuinfo_um’ has no member named ‘x86_cache_size’; did you mean ‘x86_capability’?
>>> return boot_cpu_data.x86_cache_size;
>>>
>>> ../drivers/infiniband/sw/rdmavt/qp.c: In function ‘cacheless_memcpy’:
>>> ../drivers/infiniband/sw/rdmavt/qp.c:100:2: error: implicit declaration of function ‘__copy_user_nocache’; did you mean ‘copy_user_page’? [-Werror=implicit-function-declaration]
>>> __copy_user_nocache(dst, (void __user *)src, n, 0);
>>>
>>> Fixes: 68f5d3f3b654 ("um: add PCI over virtio emulation driver")
>>> Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
>>> drivers/infiniband/sw/rdmavt/qp.c | 12 ++++++++++++
>>> 1 file changed, 12 insertions(+)
>>>
>>> +++ linux-next-20211224/drivers/infiniband/sw/rdmavt/qp.c
>>> @@ -84,10 +84,15 @@ EXPORT_SYMBOL(ib_rvt_state_ops);
>>> /* platform specific: return the last level cache (llc) size, in KiB */
>>> static int rvt_wss_llc_size(void)
>>> {
>>> +#if !defined(CONFIG_UML)
>>> /* assume that the boot CPU value is universal for all CPUs */
>>> return boot_cpu_data.x86_cache_size;
>>> +#else /* CONFIG_UML */
>>> + return 1024; /* fake 1 MB LLC size */
>>> +#endif
>>> }
>>>
>>> +#if !defined(CONFIG_UML)
>>> /* platform specific: cacheless copy */
>>> static void cacheless_memcpy(void *dst, void *src, size_t n)
>>> {
>>> @@ -99,6 +104,13 @@ static void cacheless_memcpy(void *dst,
>>> */
>>> __copy_user_nocache(dst, (void __user *)src, n, 0);
>>> }
>>> +#else
>>> +/* for CONFIG_UML, this is just a plain memcpy() */
>>> +static void cacheless_memcpy(void *dst, void *src, size_t n)
>>> +{
>>> + memcpy(dst, src, n);
>>> +}
>>> +#endif
>>
>> memcpy is not the same thing as __copy_user - the hint is in the
>> __user cast..
>>
>> It should by copy_from_user(), I think, and this is all just somehow
>> broken to not check the return code.
>
> Thanks.
>
>> Why are you trying to make a HW driver compile on UML? Is there any
>> way to even use a driver like this in a UML environment?
>
> I'm just trying to clean up lots of UML build errors.
> I'm quite happy just making the driver depend on !UML.
>
> UML maintainers, what do you think?
>
> Thanks again.
>

I would suggest that we just !UML this driver.

--
Anton R. Ivanov
Cambridgegreys Limited. Registered in England. Company Number 10273661
https://www.cambridgegreys.com/

\
 
 \ /
  Last update: 2022-01-04 09:04    [W:0.064 / U:0.284 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site