From: David Matlack <dmatlack@google.com>
To: Isaku Yamahata <isaku.yamahata@gmail.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Sean Christopherson <seanjc@google.com>,
kvm list <kvm@vger.kernel.org>, Kai Huang <kai.huang@intel.com>,
Peter Xu <peterx@redhat.com>
Subject: Re: [PATCH v2 08/10] KVM: x86/mmu: Split out TDP MMU page fault handling
Date: Tue, 20 Sep 2022 14:17:20 -0700 [thread overview]
Message-ID: <Yyot4L75h2ShPSaG@google.com> (raw)
In-Reply-To: <CALzav=fg8xonNUkbFcep6kcVcBGtsp2RRW0_NKUL8DhdbQbRPA@mail.gmail.com>
On Thu, Sep 01, 2022 at 09:50:10AM -0700, David Matlack wrote:
> On Tue, Aug 30, 2022 at 4:57 PM Isaku Yamahata <isaku.yamahata@gmail.com> wrote:
> > On Fri, Aug 26, 2022 at 04:12:25PM -0700, David Matlack <dmatlack@google.com> wrote:
> > > int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> > > {
> > > /*
> > > @@ -4355,6 +4384,11 @@ int kvm_tdp_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault)
> > > }
> > > }
> > >
> > > +#ifdef CONFIG_X86_64
> > > + if (tdp_mmu_enabled)
> > > + return kvm_tdp_mmu_page_fault(vcpu, fault);
> > > +#endif
> > > +
> > > return direct_page_fault(vcpu, fault);
> > > }
> >
> > Now we mostly duplicated page_fault method. We can go one step further.
> > kvm->arch.mmu.page_fault can be set for each case. Maybe we can do it later
> > if necessary.
>
> Hm, interesting idea. We would have to refactor the MTRR max_level
> code in kvm_tdp_page_fault() into a helper function, but otherwise
> that idea would work. I will give it a try in the next version.
So I took a stab at this. Refactoring the max_level adjustment for MTRRs
into a helper function is easy of course. But changing page_fault also
requires changes in kvm_mmu_do_page_fault() for CONFIG_RETPOLINE and
fault->is_tdp. I'm not saying it's not possible (it definitely is) but
it's not trivial to do it in a clean way, so I suggest we table this for
the time being.
next prev parent reply other threads:[~2022-09-20 21:17 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-26 23:12 [PATCH v2 00/10] KVM: x86/mmu: Make tdp_mmu read-only and clean up TPD MMU fault handler David Matlack
2022-08-26 23:12 ` [PATCH v2 01/10] KVM: x86/mmu: Change tdp_mmu to a read-only parameter David Matlack
2022-08-30 10:12 ` Huang, Kai
2022-09-01 16:47 ` David Matlack
2022-09-20 16:57 ` David Matlack
2022-09-20 17:16 ` Sean Christopherson
2022-09-20 21:01 ` Huang, Kai
2022-09-20 21:13 ` David Matlack
2022-08-26 23:12 ` [PATCH v2 02/10] KVM: x86/mmu: Move TDP MMU VM init/uninit behind tdp_mmu_enabled David Matlack
2022-08-26 23:12 ` [PATCH v2 03/10] KVM: x86/mmu: Grab mmu_invalidate_seq in kvm_faultin_pfn() David Matlack
2022-08-26 23:12 ` [PATCH v2 04/10] KVM: x86/mmu: Handle error PFNs " David Matlack
2022-08-30 23:45 ` Isaku Yamahata
2022-09-01 16:48 ` David Matlack
2022-08-26 23:12 ` [PATCH v2 05/10] KVM: x86/mmu: Avoid memslot lookup during KVM_PFN_ERR_HWPOISON handling David Matlack
2022-08-26 23:12 ` [PATCH v2 06/10] KVM: x86/mmu: Handle no-slot faults in kvm_faultin_pfn() David Matlack
2022-08-26 23:12 ` [PATCH v2 07/10] KVM: x86/mmu: Initialize fault.{gfn,slot} earlier for direct MMUs David Matlack
2022-08-26 23:12 ` [PATCH v2 08/10] KVM: x86/mmu: Split out TDP MMU page fault handling David Matlack
2022-08-30 23:57 ` Isaku Yamahata
2022-09-01 16:50 ` David Matlack
2022-09-20 21:17 ` David Matlack [this message]
2022-09-21 23:43 ` Isaku Yamahata
2022-08-26 23:12 ` [PATCH v2 09/10] KVM: x86/mmu: Stop needlessly making MMU pages available for TDP MMU faults David Matlack
2022-08-26 23:12 ` [PATCH v2 10/10] KVM: x86/mmu: Rename __direct_map() to direct_map() David Matlack
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