On 2015/5/19 15:39, Peter Zijlstra wrote: > On Tue, May 19, 2015 at 12:08:39PM +0800, Zhiqiang Zhang wrote: >> commit e00b12e64be9a34ef071de7b6052ca9ea29dd460 upstream >> >> Now that we can deal with nested NMI due to IRET re-enabling NMIs and >> can deal with faults from NMI by making sure we preserve CR2 over NMIs >> we can in fact simply access user-space memory from NMI context. >> >> So rewrite copy_from_user_nmi() to use __copy_from_user_inatomic() and >> rework the fault path to do the minimal required work before taking >> the in_atomic() fault handler. >> >> In particular avoid perf_sw_event() which would make perf recurse on >> itself (it should be harmless as our recursion protections should be >> able to deal with this -- but why tempt fate). >> >> Also rename notify_page_fault() to kprobes_fault() as that is a much >> better name; there is no notifier in it and its specific to kprobes. >> >> Don measured that his worst case NMI path shrunk from ~300K cycles to >> ~150K cycles. >> >> Cc: Stephane Eranian <eranian@xxxxxxxxxx> >> Cc: jmario@xxxxxxxxxx >> Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxxxxx> >> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> >> Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx> >> Cc: dave.hansen@xxxxxxxxxxxxxxx >> Tested-by: Don Zickus <dzickus@xxxxxxxxxx> >> Signed-off-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx> >> Link: http://lkml.kernel.org/r/20131024105206.GM2490@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx >> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> >> [zhangzhiqiang: backport to 3.10: > > Did you make sure all the nested NMI fixes are in 3.10? > > . > Sorry, i am not quite sure about that, i just using it fixes page fault from PMI. I will looking farther carefully. thanks very much. -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html