linux-kernel - Re: [PATCH] KVM: X86: Fix the decoding of segment overrides in 64bit mode

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Message-ID: <CANRm+CwmJQCFZ7oe1_YatqoOXzzEU+SP9Z5qR6zU_ybd_DoGQQ@mail.gmail.com>
Date:   Thu, 22 Mar 2018 21:39:49 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Andrew Cooper <andrew.cooper3@...rix.com>,
        LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>
Subject: Re: [PATCH] KVM: X86: Fix the decoding of segment overrides in 64bit mode

2018-03-22 20:38 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
> On 22/03/2018 12:04, Andrew Cooper wrote:
>> We've got a Force Emulation Prefix (ud2a; .ascii "xen") for doing
>> magic.  Originally, this was used for PV guests to explicitly request an
>> emulated CPUID, but I extended it to HVM guests for "emulate the next
>> instruction", after we had some guest user => guest kernel privilege
>> escalations because of incorrect emulation.
>
> Wanpeng, why don't you add it behind a new kvm module parameter? :)

Great point! I will have a try. Thanks Paolo and Andrew. :)

Regards,
Wanpeng Li