linux-kernel - Re: [PATCH v2 00/10] KVM: x86: Clean up RESET "emulation"

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Date:   Thu, 23 Sep 2021 18:23:54 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Reiji Watanabe <reijiw@...gle.com>
Subject: Re: [PATCH v2 00/10] KVM: x86: Clean up RESET "emulation"

On 21/09/21 02:02, Sean Christopherson wrote:
> Add dedicated helpers to emulate RESET (or at least, the parts of RESET
> that KVM actually emulates) instead of having the relevant code scattered
> throughout vcpu_create() and vcpu_reset().
> 
> Vitaly's innocuous suggestion to WARN on non-zero CR0 led to a wonderful
> bit of git archaeology after, to my complete surprise, it fired on RESET
> due to fx_init() setting CR0.ET (and XCR0.FP).
> 
> v2:
>   - Add patches to drop defunct fx_init() code.
>   - Add patch to zero CR3 at RESET/INIT.
>   - Add patch to mark all regs avail/dirty at creation, not at RESET/INIT.
>   - Add patch to WARN if CRs are non-zero at RESET. [Vitaly]
> 
> v1: https://lkml.kernel.org/r/20210914230840.3030620-1-seanjc@google.com
> 
> Sean Christopherson (10):
>    KVM: x86: Mark all registers as avail/dirty at vCPU creation
>    KVM: x86: Clear KVM's cached guest CR3 at RESET/INIT
>    KVM: x86: Do not mark all registers as avail/dirty during RESET/INIT
>    KVM: x86: Remove defunct setting of CR0.ET for guests during vCPU
>      create
>    KVM: x86: Remove defunct setting of XCR0 for guest during vCPU create
>    KVM: x86: Fold fx_init() into kvm_arch_vcpu_create()
>    KVM: VMX: Drop explicit zeroing of MSR guest values at vCPU creation
>    KVM: VMX: Move RESET emulation to vmx_vcpu_reset()
>    KVM: SVM: Move RESET emulation to svm_vcpu_reset()
>    KVM: x86: WARN on non-zero CRs at RESET to detect improper
>      initalization
> 
>   arch/x86/kvm/svm/sev.c |  6 ++--
>   arch/x86/kvm/svm/svm.c | 29 ++++++++++--------
>   arch/x86/kvm/svm/svm.h |  2 +-
>   arch/x86/kvm/vmx/vmx.c | 68 ++++++++++++++++++++----------------------
>   arch/x86/kvm/x86.c     | 44 +++++++++++++--------------
>   5 files changed, 76 insertions(+), 73 deletions(-)
> 

Queued 3-10 too now, thanks.

Paolo