linux-kernel - Re: [PATCH 0/4] KVM: x86/mmu: Page fault handling cleanups

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Date:   Fri, 25 Sep 2020 13:40:43 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.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, Kai Huang <kai.huang@...el.com>
Subject: Re: [PATCH 0/4] KVM: x86/mmu: Page fault handling cleanups

On Fri, Sep 25, 2020 at 10:38:02PM +0200, Paolo Bonzini wrote:
> On 24/09/20 00:04, Sean Christopherson wrote:
> > Cleanups for page fault handling that were encountered during early TDX
> > enabling, but are worthwhile on their own.  Specifically, patch 4 fixes an
> > issue where KVM doesn't detect a spurious page fault (due to the fault
> > being fixed by a different pCPU+vCPU) and does the full gamut of writing
> > the SPTE, updating stats, and prefetching SPTEs.
> > 
> > Sean Christopherson (4):
> >   KVM: x86/mmu: Return -EIO if page fault returns RET_PF_INVALID
> >   KVM: x86/mmu: Invert RET_PF_* check when falling through to emulation
> >   KVM: x86/mmu: Return unique RET_PF_* values if the fault was fixed
> >   KVM: x86/mmu: Bail early from final #PF handling on spurious faults
> > 
> >  arch/x86/kvm/mmu/mmu.c         | 70 +++++++++++++++++++++-------------
> >  arch/x86/kvm/mmu/mmutrace.h    | 13 +++----
> >  arch/x86/kvm/mmu/paging_tmpl.h |  3 ++
> >  3 files changed, 52 insertions(+), 34 deletions(-)
> > 
> 
> Queued, thanks.  Looking at the KVM_BUG_ON now since patch 1 is somewhat
> related.

Ha, very prescient of you, that's actually a KVM_BUG_ON() in my "kitchen sink"
combo of everything :-)