From patchwork Fri May 26 23:44:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Zhao X-Patchwork-Id: 13257468 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 D8520C7EE33 for ; Fri, 26 May 2023 23:45:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238032AbjEZXpZ (ORCPT ); Fri, 26 May 2023 19:45:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59114 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238105AbjEZXpC (ORCPT ); Fri, 26 May 2023 19:45:02 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 35839E4C for ; Fri, 26 May 2023 16:44:56 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-bad0f5d6a7dso2621782276.0 for ; Fri, 26 May 2023 16:44:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1685144695; x=1687736695; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=M3AF7fBmc1xnJAMOiZdfCsfXZHiS6oPk41ReBM4zbdo=; b=yrD5cypjwj76oGySeMKoL+EObdL+VlHBR0ZE4dlUQxoYbTEWiiVpSKdOJmkcaaiF/Z 4zilNg4E7S1qiA0OC/fMHUKvaq4lLe3h3XrcfBRajVZEzuTWsMjYGvjMBJ/wRyLbmfd/ x0p59R3lRKLAmUF0+sTBQhD8rRciT1hrCi2rbco+ObNSFPCgz7YI6gzDi295X90OlgMM zrJNip6i/8aKO3FHb/HgogYFOfPOgx60+DOedoHxymQQDAPdmrus+K28IPt1M7E0g0cI asbBmGj30I6PgAgE5VquUWTvHUX2/5VYaFLlsw0xBC7qUsoM7lDeTwedn+JU6nSVVIPC w2tA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685144695; x=1687736695; h=cc:to:from:subject:references:mime-version:message-id:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=M3AF7fBmc1xnJAMOiZdfCsfXZHiS6oPk41ReBM4zbdo=; b=HRmhGaTbdK3eVKjNdRFl+1fd18Qer4hCJPZJuM0vJmJcXIZPyKUc0VpYnVJRvgARpL XtdTnh0W5WCKOjdoWLeNtfWB5KY/w+NQyIJTwiyO1Ig7/oz2h6AO2x771RMPKzNK8Zb0 x/0EYfRJimbt7wLryFkZNC0QPfiD0LNwL++siSM9zNbmpDeEVAtMzCpsRN2Gg1AC7K+u 3FS9rXX2B/Sx9lLX8U4z72Lp8gvgwKNS6sDqHRq7hsCI3rvqZmy/ROOOT0GfN0kL01wi aKpWck2rjepmbS6uh8L8VAE3FwByAoxd/40eTArWW322tPF/G5I25bjUo+18YcIxWN9l c/sw== X-Gm-Message-State: AC+VfDwXUHvtnHEBnL7/cQrYmqXLKbh9ryTex8ngNOO2NLlMODeXxO8U LVD6c/+Ih8ngTQxuNQt5Bijp/gIhH1Q= X-Google-Smtp-Source: ACHHUZ4QgTvrucO0Q6McE6sU/ZYyF1Ujw9/eAceyjgq3u2aouYR16g/56Sc2t/zSHX7sxuPwIu+K0d0WjYg= X-Received: from yuzhao.bld.corp.google.com ([2620:15c:183:200:910f:8a15:592b:2087]) (user=yuzhao job=sendgmr) by 2002:a05:6902:1341:b0:bac:6bb:2549 with SMTP id g1-20020a056902134100b00bac06bb2549mr1840571ybu.7.1685144695170; Fri, 26 May 2023 16:44:55 -0700 (PDT) Date: Fri, 26 May 2023 17:44:34 -0600 In-Reply-To: <20230526234435.662652-1-yuzhao@google.com> Message-Id: <20230526234435.662652-10-yuzhao@google.com> Mime-Version: 1.0 References: <20230526234435.662652-1-yuzhao@google.com> X-Mailer: git-send-email 2.41.0.rc0.172.g3f132b7071-goog Subject: [PATCH mm-unstable v2 09/10] kvm/x86: add kvm_arch_test_clear_young() From: Yu Zhao To: Andrew Morton , Paolo Bonzini Cc: Alistair Popple , Anup Patel , Ben Gardon , Borislav Petkov , Catalin Marinas , Chao Peng , Christophe Leroy , Dave Hansen , Fabiano Rosas , Gaosheng Cui , Gavin Shan , "H. Peter Anvin" , Ingo Molnar , James Morse , "Jason A. Donenfeld" , Jason Gunthorpe , Jonathan Corbet , Marc Zyngier , Masami Hiramatsu , Michael Ellerman , Michael Larabel , Mike Rapoport , Nicholas Piggin , Oliver Upton , Paul Mackerras , Peter Xu , Sean Christopherson , Steven Rostedt , Suzuki K Poulose , Thomas Gleixner , Thomas Huth , Will Deacon , Zenghui Yu , kvmarm@lists.linux.dev, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-trace-kernel@vger.kernel.org, x86@kernel.org, linux-mm@google.com, Yu Zhao Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org Implement kvm_arch_test_clear_young() to support the fast path in mmu_notifier_ops->test_clear_young(). It focuses on a simple case, i.e., TDP MMU sets the accessed bit in KVM PTEs and VMs are not nested, where it can rely on RCU and clear_bit() to safely clear the accessed bit without taking kvm->mmu_lock. Complex cases fall back to the existing slow path where kvm->mmu_lock is then taken. Signed-off-by: Yu Zhao --- arch/x86/include/asm/kvm_host.h | 7 +++++++ arch/x86/kvm/mmu/tdp_mmu.c | 34 +++++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 753c67072c47..d6dfdebe3d94 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -2223,4 +2223,11 @@ int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages); */ #define KVM_EXIT_HYPERCALL_MBZ GENMASK_ULL(31, 1) +#define kvm_arch_has_test_clear_young kvm_arch_has_test_clear_young +static inline bool kvm_arch_has_test_clear_young(void) +{ + return IS_ENABLED(CONFIG_X86_64) && + (!IS_REACHABLE(CONFIG_KVM) || (tdp_mmu_enabled && shadow_accessed_mask)); +} + #endif /* _ASM_X86_KVM_HOST_H */ diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 08340219c35a..6875a819e007 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1232,6 +1232,40 @@ bool kvm_tdp_mmu_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range) return kvm_tdp_mmu_handle_gfn(kvm, range, test_age_gfn); } +bool kvm_arch_test_clear_young(struct kvm *kvm, struct kvm_gfn_range *range) +{ + struct kvm_mmu_page *root; + int offset = ffs(shadow_accessed_mask) - 1; + + if (kvm_shadow_root_allocated(kvm)) + return true; + + rcu_read_lock(); + + list_for_each_entry_rcu(root, &kvm->arch.tdp_mmu_roots, link) { + struct tdp_iter iter; + + if (kvm_mmu_page_as_id(root) != range->slot->as_id) + continue; + + tdp_root_for_each_leaf_pte(iter, root, range->start, range->end) { + u64 *sptep = rcu_dereference(iter.sptep); + + VM_WARN_ON_ONCE(!page_count(virt_to_page(sptep))); + + if (!(iter.old_spte & shadow_accessed_mask)) + continue; + + if (kvm_should_clear_young(range, iter.gfn)) + clear_bit(offset, (unsigned long *)sptep); + } + } + + rcu_read_unlock(); + + return false; +} + static bool set_spte_gfn(struct kvm *kvm, struct tdp_iter *iter, struct kvm_gfn_range *range) {