On 05/20/2015 03:05 AM, Ingo Molnar wrote: >> > >> > This sees breakage unless either booted with 'noxsaves' >> > or if it has Fenghua's set from here applied: >> > >> > >> > http://lkml.kernel.org/r/1429678319-61356-1-git-send-email-fenghua...@intel.com >> > >> > This set is also available against 4.1-rc3 in git: >> > >> > git://git.kernel.org/pub/scm/linux/kernel/git/daveh/x86-mpx.git mpx-v22 > Yeah, so as a first step, could you please test that the patch below > solves the crashes as well, without having to specify 'noxsaves' on > the boot line?
Yes, that does seem to make it happy in lieu of Fenghua's patches. > + /* > + * Quirk: we don't yet handle the XSAVES* instructions > + * correctly, as we don't correctly convert between > + * standard and compacted format when interfacing > + * with user-space - so disable it for now. > + * > + * The difference is small: with recent CPUs the > + * compacted format is only marginally smaller than > + * the standard FPU state format. > + * > + * ( This is easy to backport while we are fixing > + * XSAVES* support. ) > + */ > + setup_clear_cpu_cap(X86_FEATURE_XSAVES); > } FWIW, I think it would be prudent to also clear X86_FEATURE_XSAVEC. All of the issues I am aware of are related to the compact format, not 'xsaves' itself (although 'xsaves' does *use* the compact format of course). The XSAVEC bit is the one that technically indicates the compact format support, although I don't think there is any actual use of it in the kernel at present. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
