From nobody Tue Feb 10 01:19:17 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 31024C6FD1D for ; Tue, 21 Mar 2023 22:01:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230260AbjCUWBU (ORCPT ); Tue, 21 Mar 2023 18:01:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230221AbjCUWBA (ORCPT ); Tue, 21 Mar 2023 18:01:00 -0400 Received: from mail-yw1-x114a.google.com (mail-yw1-x114a.google.com [IPv6:2607:f8b0:4864:20::114a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 76B2858C06 for ; Tue, 21 Mar 2023 15:00:38 -0700 (PDT) Received: by mail-yw1-x114a.google.com with SMTP id 00721157ae682-540e3b152a3so167691837b3.2 for ; Tue, 21 Mar 2023 15:00:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; t=1679436037; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=l3JzYD0u087M8uWewJDs63iio7s7LCBf0UooyaaQZak=; b=sPfaqDOE7yWhSuiUIZf0xd+k0PDvbafdbkdbHy9oZQ50zsLIKXlNo4EApjcM1z4yXY 9/ZRMbMHteBU7UnlaUQlJB83EZFWV6DqQLgv/3l95DfrZ07rsVGjeprJ4Jlt9TGlI6A1 Mz9CElVjeppNfWHMD3wYKaOjvH2MuEeM3SMsArkPXwg3cpCopPUsnPJU0ggZI/oGJMKj t2zLZFRLThgRMWoaLHb3zSCfQKrIbKvLhuYiQXflYK36QWSPTN1q4hq5AH8M3dpCnyW4 hB0Ewf4SzzL44avvLXFFBq2aomaMHTMr3mMskq3FCfPKAsd8Hca1vd6hDtU9ajGSQbby jbtQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; t=1679436037; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=l3JzYD0u087M8uWewJDs63iio7s7LCBf0UooyaaQZak=; b=YTX8bQc8NFfTmBRrPcEV7V/q31+XPv7VStnnFAUyT2whPIY4RWu5ybB15pIhBanNqi rEwG+2hGb+CY/y4TrM1ndzDSVP6MTsOYmq/Xxn9U2+oz956RaJBoPQhtC8GaoP5QHiAS fTbNDr9pCE4dTrICwVietsMeiGdPz+6gDGix4hEqqZ6eTmGH3eJlhJbygkd+7i2ZsPzf mGzzcZ7CkNM942Iwp0ZrR8zDEHxgB9xeGlQHrZO0DkC7tIqVid8YM76mbaEUCZUGDcRg 7AV34FX4EgCOp7UqIs+BiJFvr4NvhGd9ZwGKtFR9lHuFkzeoOobhPOv/RcxlgdgRtBlk 3RbA== X-Gm-Message-State: AAQBX9cUZuu1TIiF4o8y1pcIdZ19MJfPpdKkJ+qUzBr+0ak57Dmq8nm9 udeqffPX2cp5uqsXD9W0qxWzu4a5ni4= X-Google-Smtp-Source: AKy350ZrJiZIL9DkISdCz4U34JRpP0pdOec2sduVj6biEF/6aEeFwAoFopPBaLpv1b0ftiNSOQQL+BhsVz0= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6902:283:b0:b6e:d788:eba7 with SMTP id v3-20020a056902028300b00b6ed788eba7mr2491158ybh.6.1679436037531; Tue, 21 Mar 2023 15:00:37 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 21 Mar 2023 15:00:16 -0700 In-Reply-To: <20230321220021.2119033-1-seanjc@google.com> Mime-Version: 1.0 References: <20230321220021.2119033-1-seanjc@google.com> X-Mailer: git-send-email 2.40.0.rc2.332.ga46443480c-goog Message-ID: <20230321220021.2119033-9-seanjc@google.com> Subject: [PATCH v4 08/13] KVM: x86/mmu: Clear only A-bit (if enabled) when aging TDP MMU SPTEs From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Vipin Sharma , David Matlack , Ben Gardon Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Vipin Sharma Use tdp_mmu_clear_spte_bits() when clearing the Accessed bit in TDP MMU SPTEs so as to use an atomic-AND instead of XCHG to clear the A-bit. Similar to the D-bit story, this will allow KVM to bypass __handle_changed_spte() by ensuring only the A-bit is modified. Link: https://lore.kernel.org/all/Y9HcHRBShQgjxsQb@google.com Signed-off-by: Vipin Sharma Reviewed-by: David Matlack [sean: massage changelog] Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/tdp_mmu.c | 38 +++++++++++++++++++++----------------- 1 file changed, 21 insertions(+), 17 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 3cc81fa22b7f..adbdfed287cc 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -756,13 +756,6 @@ static inline void tdp_mmu_set_spte(struct kvm *kvm, s= truct tdp_iter *iter, _tdp_mmu_set_spte(kvm, iter, new_spte, true); } =20 -static inline void tdp_mmu_set_spte_no_acc_track(struct kvm *kvm, - struct tdp_iter *iter, - u64 new_spte) -{ - _tdp_mmu_set_spte(kvm, iter, new_spte, false); -} - #define tdp_root_for_each_pte(_iter, _root, _start, _end) \ for_each_tdp_pte(_iter, _root, _start, _end) =20 @@ -1248,33 +1241,44 @@ static __always_inline bool kvm_tdp_mmu_handle_gfn(= struct kvm *kvm, /* * Mark the SPTEs range of GFNs [start, end) unaccessed and return non-zero * if any of the GFNs in the range have been accessed. + * + * No need to mark the corresponding PFN as accessed as this call is coming + * from the clear_young() or clear_flush_young() notifier, which uses the + * return value to determine if the page has been accessed. */ static bool age_gfn_range(struct kvm *kvm, struct tdp_iter *iter, struct kvm_gfn_range *range) { - u64 new_spte =3D 0; + u64 new_spte; =20 /* If we have a non-accessed entry we don't need to change the pte. */ if (!is_accessed_spte(iter->old_spte)) return false; =20 - new_spte =3D iter->old_spte; - - if (spte_ad_enabled(new_spte)) { - new_spte &=3D ~shadow_accessed_mask; + if (spte_ad_enabled(iter->old_spte)) { + iter->old_spte =3D tdp_mmu_clear_spte_bits(iter->sptep, + iter->old_spte, + shadow_accessed_mask, + iter->level); + new_spte =3D iter->old_spte & ~shadow_accessed_mask; } else { /* * Capture the dirty status of the page, so that it doesn't get * lost when the SPTE is marked for access tracking. */ - if (is_writable_pte(new_spte)) - kvm_set_pfn_dirty(spte_to_pfn(new_spte)); + if (is_writable_pte(iter->old_spte)) + kvm_set_pfn_dirty(spte_to_pfn(iter->old_spte)); =20 - new_spte =3D mark_spte_for_access_track(new_spte); + new_spte =3D mark_spte_for_access_track(iter->old_spte); + iter->old_spte =3D kvm_tdp_mmu_write_spte(iter->sptep, + iter->old_spte, new_spte, + iter->level); } =20 - tdp_mmu_set_spte_no_acc_track(kvm, iter, new_spte); - + __handle_changed_spte(kvm, iter->as_id, iter->gfn, iter->old_spte, + new_spte, iter->level, false); + handle_changed_spte_dirty_log(kvm, iter->as_id, iter->gfn, + iter->old_spte, new_spte, iter->level); return true; } =20 --=20 2.40.0.rc2.332.ga46443480c-goog