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@xxxxxxxxxxxxx>
> 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.
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?
Jason
