Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

Brian Gerst
2014-04-12T20:34:18Z

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.