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List:       linux-kernel
Subject:    Re: [PATCH 0/8] x86/fpu: Remove CR0.TS support
From:       Borislav Petkov <bp () alien8 ! de>
Date:       2016-10-31 23:48:55
Message-ID: 20161031234855.qu64eamohn35jdo4 () pd ! tnic
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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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