From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: Vitaly Kuznetsov <vkuznets@redhat.com>,
Wanpeng Li <wanpengli@tencent.com>,
Jim Mattson <jmattson@google.com>, Joerg Roedel <joro@8bytes.org>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 00/13] KVM: x86: Allow userspace to disable the emulator
Date: Mon, 2 Mar 2020 12:02:29 -0800 [thread overview]
Message-ID: <20200302200229.GE6244@linux.intel.com> (raw)
In-Reply-To: <3ec358a8-859d-9ef1-7392-372d55b28ee4@redhat.com>
On Mon, Mar 02, 2020 at 07:42:31PM +0100, Paolo Bonzini wrote:
> On 19/02/20 00:29, Sean Christopherson wrote:
> > The primary intent of this series is to dynamically allocate the emulator
> > and get KVM to a state where the emulator *could* be disabled at some
> > point in the future. Actually allowing userspace to disable the emulator
> > was a minor change at that point, so I threw it in.
> >
> > Dynamically allocating the emulator shrinks the size of x86 vcpus by
> > ~2.5k bytes, which is important because 'struct vcpu_vmx' has once again
> > fattened up and squeaked past the PAGE_ALLOC_COSTLY_ORDER threshold.
> > Moving the emulator to its own allocation gives us some breathing room
> > for the near future, and has some other nice side effects.
> >
> > As for disabling the emulator... in the not-too-distant future, I expect
> > there will be use cases that can truly disable KVM's emulator, e.g. for
> > security (KVM's and/or the guests). I don't have a strong opinion on
> > whether or not KVM should actually allow userspace to disable the emulator
> > without a concrete use case (unless there already is a use case?), which
> > is why that part is done in its own tiny patch.
> >
> > Running without an emulator has been "tested" in the sense that the
> > selftests that don't require emulation continue to pass, and everything
> > else fails with the expected "emulation error".
>
> I agree with Vitaly that, if we want this, it should be a KVM_ENABLE_CAP
> instead. The first 10 patches are very nice cleanups though so I plan
> to apply them (with Vitaly's suggested nits for review) after you answer
> the question on patch 10.
Works for me, thanks!
prev parent reply other threads:[~2020-03-02 20:02 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 23:29 [PATCH v2 00/13] KVM: x86: Allow userspace to disable the emulator Sean Christopherson
2020-02-18 23:29 ` [PATCH v2 01/13] KVM: x86: Refactor I/O emulation helpers to provide vcpu-only variant Sean Christopherson
2020-02-26 15:16 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 02/13] KVM: x86: Explicitly pass an exception struct to check_intercept Sean Christopherson
2020-02-18 23:29 ` [PATCH v2 03/13] KVM: x86: Move emulation-only helpers to emulate.c Sean Christopherson
2020-02-26 15:23 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 04/13] KVM: x86: Refactor R/W page helper to take the emulation context Sean Christopherson
2020-02-26 15:24 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 05/13] KVM: x86: Refactor emulated exception injection to take the emul context Sean Christopherson
2020-02-26 15:25 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 06/13] KVM: x86: Refactor emulate tracepoint to explicitly take context Sean Christopherson
2020-02-26 17:11 ` Vitaly Kuznetsov
2020-03-03 16:48 ` Sean Christopherson
2020-03-03 17:29 ` Paolo Bonzini
2020-03-03 17:42 ` Sean Christopherson
2020-03-03 17:44 ` Paolo Bonzini
2020-02-18 23:29 ` [PATCH v2 07/13] KVM: x86: Refactor init_emulate_ctxt() " Sean Christopherson
2020-02-26 17:13 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 08/13] KVM: x86: Dynamically allocate per-vCPU emulation context Sean Christopherson
2020-02-26 17:29 ` Vitaly Kuznetsov
2020-03-03 10:26 ` Paolo Bonzini
2020-03-03 14:57 ` Sean Christopherson
2020-03-03 16:18 ` Vitaly Kuznetsov
2020-03-03 16:52 ` Sean Christopherson
2020-02-18 23:29 ` [PATCH v2 09/13] KVM: x86: Move kvm_emulate.h into KVM's private directory Sean Christopherson
2020-02-26 17:38 ` Vitaly Kuznetsov
2020-03-03 10:27 ` Paolo Bonzini
2020-02-18 23:29 ` [PATCH v2 10/13] KVM: x86: Shrink the usercopy region of the emulation context Sean Christopherson
2020-02-26 17:51 ` Vitaly Kuznetsov
2020-03-02 18:40 ` Paolo Bonzini
2020-03-02 19:19 ` Sean Christopherson
2020-03-02 19:13 ` Sean Christopherson
2020-02-18 23:29 ` [PATCH v2 11/13] KVM: x86: Add helper to "handle" internal emulation error Sean Christopherson
2020-02-26 17:52 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 12/13] KVM: x86: Add variable to control existence of emulator Sean Christopherson
2020-02-26 18:01 ` Vitaly Kuznetsov
2020-02-18 23:29 ` [PATCH v2 13/13] KVM: x86: Allow userspace to disable the kernel's emulator Sean Christopherson
2020-03-02 18:42 ` [PATCH v2 00/13] KVM: x86: Allow userspace to disable the emulator Paolo Bonzini
2020-03-02 20:02 ` Sean Christopherson [this message]
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