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Date: Sat, 12 Apr 2014 16:34:14 -0400
Message-ID: <CAMzpN2jHrBZ7DCd79GkCdjwCWJBv+YR5o9BGjypCdazJB9bJYQ@mail.gmail.com>
Subject: Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on
 64-bit kernels
From: Brian Gerst <brgerst@gmail.com>
To: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, stable <stable@vger.kernel.org>,
        "H. Peter Anvin" <hpa@linux.intel.com>
Content-Type: text/plain; charset=UTF-8
Sender: linux-kernel-owner@vger.kernel.org

On Sat, Apr 12, 2014 at 4:11 PM, Borislav Petkov <bp@alien8.de> wrote:
> On Sat, Apr 12, 2014 at 12:44:42PM -0700, H. Peter Anvin wrote:
>> Run a 32-bit VM.  The 32-bit kernel does this right.
>
> Yes, even better.
>
>> I suspect it would also work fine in a Qemu user mode guest (is
>> this supported by KVM?), in a ReactOS VM, or some other number of
>> combinations.
>
> Right.
>
> So basically, there a lot of different virt scenarios which can all take
> care of those use cases *without* encumbering some insane solutions on
> 64-bit.
>
>> The real question is how many real users are actually affected.
>
> And if they are, virtualize them, for chrissake. It is time we finally
> used virt for maybe one of its major use cases - virtualize old/obscure
> hw. It should be pretty reliable by now.
>
> :-P
>
> --
> Regards/Gruss,
>     Boris.
>
> Sent from a fat crate under my desk. Formatting is fine.
> --

My experience with kvm so far is that is slow and clunky.  It may be
OK for a server environment, but interactively it's difficult to use.
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