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Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support

From Borislav Petkov <bp@alien8.de>
Newsgroups linux.kernel
Subject Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support
Date 2016-11-01 01:00 +0100
Message-ID <syuEF-LM-1@gated-at.bofh.it> (permalink)
References <syt5U-8pE-3@gated-at.bofh.it> <sytyW-8o-19@gated-at.bofh.it> <sytSh-uI-9@gated-at.bofh.it> <syu1Y-yg-21@gated-at.bofh.it>
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On Tue, Nov 01, 2016 at 12:10:48AM +0100, Paul Bolle wrote:
> See https://lists.ozlabs.org/pipermail/lguest/2013-May/002001.html .
> Nobody cared enough to fix it. I cared enough to figure it all out. But
> I didn't understand much of the possible solutions that where suggested
> three years ago.

I'm guessing the simple fix would be this:

---
diff --git a/drivers/lguest/Kconfig b/drivers/lguest/Kconfig
index 169172d2ba05..9c08b3050bb7 100644
--- a/drivers/lguest/Kconfig
+++ b/drivers/lguest/Kconfig
@@ -1,6 +1,6 @@
 config LGUEST
 	tristate "Linux hypervisor example code"
-	depends on X86_32 && EVENTFD && TTY && PCI_DIRECT
+	depends on X86_32 && EVENTFD && TTY && PCI_DIRECT && !MICROCODE
 	select HVC_DRIVER
 	---help---
 	  This is a very simple module which allows you to run
---

but maybe the better fix is to hack in MSR emulation in lguest and
intercept the *MSR accesses and do the writes/reads in the exception
fixup and ...

I haven't looked at the lguest code, of course and whether that's easily
doable and whether it even makes sense and whether one should simply use
qemu/kvm instead and, and, and...

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.

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Thread

[PATCH 0/8] x86/fpu: Remove CR0.TS support Andy Lutomirski <luto@kernel.org> - 2016-10-31 23:20 +0100
  [PATCH 5/8] lguest: Remove CR0.TS support Andy Lutomirski <luto@kernel.org> - 2016-10-31 23:30 +0100
    [tip:x86/fpu] x86/fpu, lguest: Remove CR0.TS support tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-11-01 08:20 +0100
  [PATCH 8/8] x86/fpu: Remove clts() Andy Lutomirski <luto@kernel.org> - 2016-10-31 23:30 +0100
    [tip:x86/fpu] x86/fpu: Remove clts() tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-11-01 08:20 +0100
  [PATCH 2/8] fpu/bugs: Stop saving and restoring CR0.TS in fpu__init_check_bugs() Andy Lutomirski <luto@kernel.org> - 2016-10-31 23:30 +0100
    [tip:x86/fpu] x86/fpu: Stop saving and restoring CR0.TS in  fpu__init_check_bugs() tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-11-01 08:20 +0100
  [PATCH 7/8] x86/fpu: Remove stts() Andy Lutomirski <luto@kernel.org> - 2016-10-31 23:30 +0100
    [tip:x86/fpu] x86/fpu: Remove stts() tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-11-01 08:20 +0100
  Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support Paul Bolle <pebolle@tiscali.nl> - 2016-10-31 23:50 +0100
    Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support Borislav Petkov <bp@alien8.de> - 2016-11-01 00:10 +0100
      Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support Paul Bolle <pebolle@tiscali.nl> - 2016-11-01 00:20 +0100
        Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support Borislav Petkov <bp@alien8.de> - 2016-11-01 01:00 +0100
          Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support Paul Bolle <pebolle@tiscali.nl> - 2016-11-01 09:00 +0100
            Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support Borislav Petkov <bp@alien8.de> - 2016-11-01 10:00 +0100

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