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Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention

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On Fri, 2017-03-10 at 06:17 -0800, Andy Lutomirski wrote:
> On Fri, Mar 10, 2017 at 3:33 AM, Stas Sergeev <stsp@list.ru> wrote:
> > 10.03.2017 05:39, Andy Lutomirski пишет:
> >
> >> On Thu, Mar 9, 2017 at 2:10 PM, Stas Sergeev <stsp@list.ru> wrote:
> >>>
> >>> 09.03.2017 04:15, Ricardo Neri пишет:
> >>>
> >>>> On Wed, 2017-03-08 at 08:46 -0800, Andy Lutomirski wrote:
> >>>>>
> >>>>> On Wed, Mar 8, 2017 at 8:29 AM, Stas Sergeev <stsp@list.ru> wrote:
> >>>>>>
> >>>>>> 08.03.2017 19:06, Andy Lutomirski пишет:
> >>>>>>>
> >>>>>>> On Wed, Mar 8, 2017 at 6:08 AM, Stas Sergeev <stsp@list.ru> wrote:
> >>>>>>>>
> >>>>>>>> 08.03.2017 03:32, Ricardo Neri пишет:
> >>>>>>>>>
> >>>>>>>>> These are the instructions covered by UMIP:
> >>>>>>>>> * SGDT - Store Global Descriptor Table
> >>>>>>>>> * SIDT - Store Interrupt Descriptor Table
> >>>>>>>>> * SLDT - Store Local Descriptor Table
> >>>>>>>>> * SMSW - Store Machine Status Word
> >>>>>>>>> * STR - Store Task Register
> >>>>>>>>>
> >>>>>>>>> This patchset initially treated tasks running in virtual-8086
> >>>>>
> >>>>> mode as a
> >>>>>>>>>
> >>>>>>>>> special case. However, I received clarification that DOSEMU[8]
> >>>>>
> >>>>> does not
> >>>>>>>>>
> >>>>>>>>> support applications that use these instructions.
> >>>>>>>
> >>>>>>> Can you remind me what was special about it?  It looks like you
> >>>>>
> >>>>> still
> >>>>>>>
> >>>>>>> emulate them in v8086 mode.
> >>>>>>
> >>>>>> Indeed, sorry, I meant prot mode here. :)
> >>>>>> So I wonder what was cited to be special about v86.
> >>>>
> >>>> Initially my patches disabled UMIP on virtual-8086 instructions, without
> >>>> regards of protected mode (i.e., UMIP was always enabled). I didn't have
> >>>> emulation at the time. Then, I added emulation code that now covers
> >>>> protected and virtual-8086 modes. I guess it is not special anymore.
> >>>
> >>> But isn't SLDT&friends just throw UD in v86?
> >>> How does UMIP affect this? How does your patch affect
> >>> this?
> >>
> >> Er, right.  Ricardo, your code may need fixing.  But don't you have a
> >> test case for this?
> >
> > Why would you need one?
> > Or do you really want to allow these instructions
> > in v86 by the means of emulation? If so - this wasn't
> > clearly stated in the patch description, neither it was
> > properly discussed, it seems.
> 
> What I meant was: if the patches incorrectly started making these
> instructions work in vm86 mode where they used to cause a vm86 exit,
> then that's a bug that the selftest should have caught.

Yes, this is the case. I will fix this behavior... and update the test
cases.

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[v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 09/21] x86/insn-eval: Add functions to get default operand and address sizes Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 03/21] x86/mpx: Do not use R/EBP as base in the SIB byte with Mod = 0 Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 08/21] x86/insn-eval: Add utility function to get segment descriptor base address Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 15/21] x86/mm: Relocate page fault error codes to traps.h Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
    Re: [v6 PATCH 15/21] x86/mm: Relocate page fault error codes to traps.h Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:10 +0100
  [v6 PATCH 11/21] insn/eval: Incorporate segment base in address computation Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 16/21] x86/cpufeature: Add User-Mode Instruction Prevention definitions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 21/21] selftests/x86: Add tests for User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
    Re: [v6 PATCH 21/21] selftests/x86: Add tests for User-Mode  Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:30 +0100
      Re: [v6 PATCH 21/21] selftests/x86: Add tests for User-Mode  Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 00:40 +0100
  [v6 PATCH 01/21] x86/mpx: Use signed variables to compute effective addresses Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:40 +0100
  [v6 PATCH 20/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 13/21] x86/insn-eval: Add support to resolve 16-bit addressing encodings Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 17/21] x86: Add emulation code for UMIP instructions Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 05/21] x86/insn-eval: Add utility functions to get register offsets Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 12/21] x86/insn: Support both signed 32-bit and 64-bit effective addresses Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 07/21] x86/insn-eval: Add utility function to get segment descriptor Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 18/21] x86/umip: Force a page fault when unable to copy emulated result to user Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 14/21] x86/insn-eval: Add wrapper function for 16-bit and 32-bit address encodings Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 01:50 +0100
  [v6 PATCH 06/21] x86/insn-eval: Add utility functions to get segment selector Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:00 +0100
  [v6 PATCH 02/21] x86/mpx: Do not use SIB index if index points to R/ESP Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:00 +0100
  [v6 PATCH 19/21] x86/traps: Fixup general protection faults caused by UMIP Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:00 +0100
    Re: [v6 PATCH 19/21] x86/traps: Fixup general protection faults  caused by UMIP Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:00 +0100
  [v6 PATCH 10/21] x86/insn-eval: Do not use R/EBP as base if mod in ModRM is zero Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 02:10 +0100
  [v6 PATCH 04/21] x86/mpx, x86/insn: Relocate insn util functions to a new insn-kernel Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-08 04:50 +0100
  Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-08 15:30 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-08 18:00 +0100
      Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-09 02:20 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-09 23:10 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@kernel.org> - 2017-03-10 03:50 +0100
          Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 22:00 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-10 22:10 +0100
              Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 22:40 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 18:20 +0100
      Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-09 02:20 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-09 23:20 +0100
          Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-10 03:50 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 12:40 +0100
              Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-10 15:20 +0100
                Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 02:30 +0100
              Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 01:10 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 01:00 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-08 23:30 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 23:50 +0100
    Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-09 02:50 +0100
      Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-10 02:30 +0100
        Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 00:50 +0100
          Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Stas Sergeev <stsp@list.ru> - 2017-03-11 01:00 +0100
            Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Ricardo Neri <ricardo.neri-calderon@linux.intel.com> - 2017-03-11 01:20 +0100
  Re: [v6 PATCH 00/21] x86: Enable User-Mode Instruction Prevention Andy Lutomirski <luto@amacapital.net> - 2017-03-08 17:20 +0100

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