linux-kernel - Re: [PATCH 1/2] kvm: x86/mmu: Add existing trace points to TDP MMU

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Date:   Mon, 16 Nov 2020 11:15:34 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     LKML <linux-kernel@...r.kernel.org>, kvm <kvm@...r.kernel.org>
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Peter Shier <pshier@...gle.com>,
        Junaid Shahid <junaids@...gle.com>,
        Peter Feiner <pfeiner@...gle.com>
Subject: Re: [PATCH 1/2] kvm: x86/mmu: Add existing trace points to TDP MMU

On Tue, Oct 27, 2020 at 10:59 AM Ben Gardon <bgardon@...gle.com> wrote:
>
> The TDP MMU was initially implemented without some of the usual
> tracepoints found in mmu.c. Correct this discrepancy by adding the
> missing trace points to the TDP MMU.
>
> Tested: ran the demand paging selftest on an Intel Skylake machine with
>         all the trace points used by the TDP MMU enabled and observed
>         them firing with expected values.
>
> This patch can be viewed in Gerrit at:
> https://linux-review.googlesource.com/c/virt/kvm/kvm/+/3812
>
> Signed-off-by: Ben Gardon <bgardon@...gle.com>
> ---
>  arch/x86/kvm/mmu/tdp_mmu.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
> index 27e381c9da6c2..047e2d966abef 100644
> --- a/arch/x86/kvm/mmu/tdp_mmu.c
> +++ b/arch/x86/kvm/mmu/tdp_mmu.c
> @@ -7,6 +7,8 @@
>  #include "tdp_mmu.h"
>  #include "spte.h"
>
> +#include <trace/events/kvm.h>
> +
>  #ifdef CONFIG_X86_64
>  static bool __read_mostly tdp_mmu_enabled = false;
>  module_param_named(tdp_mmu, tdp_mmu_enabled, bool, 0644);
> @@ -101,6 +103,8 @@ static struct kvm_mmu_page *alloc_tdp_mmu_page(struct kvm_vcpu *vcpu, gfn_t gfn,
>         sp->gfn = gfn;
>         sp->tdp_mmu_page = true;
>
> +       trace_kvm_mmu_get_page(sp, true);
> +
>         return sp;
>  }
>
> @@ -271,6 +275,8 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
>                 pt = spte_to_child_pt(old_spte, level);
>                 sp = sptep_to_sp(pt);
>
> +               trace_kvm_mmu_prepare_zap_page(sp);
> +
>                 list_del(&sp->link);
>
>                 if (sp->lpage_disallowed)
> @@ -473,11 +479,13 @@ static int tdp_mmu_map_handle_target_level(struct kvm_vcpu *vcpu, int write,
>         if (unlikely(is_noslot_pfn(pfn))) {
>                 new_spte = make_mmio_spte(vcpu, iter->gfn, ACC_ALL);
>                 trace_mark_mmio_spte(iter->sptep, iter->gfn, new_spte);
> -       } else
> +       } else {
>                 make_spte_ret = make_spte(vcpu, ACC_ALL, iter->level, iter->gfn,
>                                          pfn, iter->old_spte, prefault, true,
>                                          map_writable, !shadow_accessed_mask,
>                                          &new_spte);
> +               trace_kvm_mmu_set_spte(iter->level, iter->gfn, iter->sptep);
> +       }
>
>         if (new_spte == iter->old_spte)
>                 ret = RET_PF_SPURIOUS;
> @@ -691,6 +699,8 @@ static int age_gfn_range(struct kvm *kvm, struct kvm_memory_slot *slot,
>
>                 tdp_mmu_set_spte_no_acc_track(kvm, &iter, new_spte);
>                 young = 1;
> +
> +               trace_kvm_age_page(iter.gfn, iter.level, slot, young);
>         }
>
>         return young;
> --
> 2.29.0.rc2.309.g374f81d7ae-goog
>

If anyone has time to review this short series, I'd appreciate it. I
don't want these to get lost in the shuffle.
Thanks!