linux-kernel - Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the next instruction"

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Message-ID: <CANRm+Cw7VVNmA=DvrzbUDoTQZ_O2sTQVJiu-v-fVt+e3jfB_gw@mail.gmail.com>
Date:   Tue, 27 Mar 2018 13:03:15 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Andrew Cooper <andrew.cooper3@...rix.com>
Subject: Re: [PATCH 2/2] KVM: VMX: Add Force Emulation Prefix for "emulate the
 next instruction"

2018-03-27 12:55 GMT+08:00 Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>:
> On Tue, Mar 27, 2018 at 12:40:20AM -0400, Konrad Rzeszutek Wilk wrote:
>> On Mon, Mar 26, 2018 at 07:12:15PM -0700, Wanpeng Li wrote:
>> > From: Wanpeng Li <wanpengli@...cent.com>
>> >
>> > This patch introduces a Force Emulation Prefix (ud2a; .ascii "kvm") for
>> > "emulate the next instruction", the codes will be executed by emulator
>> > instead of processor, for testing purposes.
>>
>> Can you expand a bit ? Why do you want this in KVM in the first place?

Please refer to the original discussion(Force Emulation Prefix part).
https://lkml.org/lkml/2018/3/22/220

>> Should this be controlled by a boolean parameter?
>
> .. per guest. That is instead of a global one, have a per guest one?

As Paolo pointed out offline:
> Testing without the hacks being done by emulator.flat (TLB mismatch between instructions and data).
I think a global module is enough for testing.

Regards,
Wanpeng Li