linux-kernel - Re: [PATCH 0/5] KVM: VMX: Add caching of EXIT_QUAL and INTR

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Message-ID: <d449f6e3-ca28-2fac-e4ed-7dea2729d3b5@redhat.com>
Date:   Thu, 16 Apr 2020 15:42:00 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Sean Christopherson <sean.j.christopherson@...el.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
Subject: Re: [PATCH 0/5] KVM: VMX: Add caching of EXIT_QUAL and INTR_INFO

On 15/04/20 22:34, Sean Christopherson wrote:
> Patches 4-5 are the focus of this series, adding caching of
> vmcs.EXIT_QUALIFICATION and proper caching of vmcs.INTR_INFO (instead of
> caching it with ad hoc rules about when it's available).  Patches 1-3
> are prep work to clean up the register caching to ensure correctness when
> switching between vmcs01 and vmcs02.
> 
> The idea for this came about when working on the "unionize exit_reason"
> series.  The nested VM-Exit logic looks at both fields multiple times,
> which is ok-ish when everything is crammed into one or two functions, but
> incurs multiple VMREADs when split up.  I really didn't want to solve that
> issue by piling on more cases where vmx->exit_intr_info would be valid, or
> by duplicating that fragile pattern for exit_qualification.
> 
> Paolo, this will conflict with the "unionize exit_reason" series, though
> the conflict resolution is all mechnical in nature.  Let me know if you
> want me to respin one on top of the other, send a single series, etc...

Queued, I think I fixed the conflicts right.  We'll see if anything
explodes when I test it. :)

Paolo

> 
> Sean Christopherson (5):
>   KVM: nVMX: Invoke ept_save_pdptrs() if and only if PAE paging is
>     enabled
>   KVM: nVMX: Reset register cache (available and dirty masks) on VMCS
>     switch
>   KVM: nVMX: Drop manual clearing of segment cache on nested VMCS switch
>   KVM: VMX: Cache vmcs.EXIT_QUALIFICATION using arch avail_reg flags
>   KVM: VMX: Cache vmcs.EXIT_INTR_INFO using arch avail_reg flags
> 
>  arch/x86/include/asm/kvm_host.h |  2 +
>  arch/x86/kvm/vmx/nested.c       | 29 +++++++------
>  arch/x86/kvm/vmx/nested.h       |  4 +-
>  arch/x86/kvm/vmx/vmx.c          | 73 ++++++++++++++++-----------------
>  arch/x86/kvm/vmx/vmx.h          | 35 +++++++++++++++-
>  5 files changed, 86 insertions(+), 57 deletions(-)
>