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: 13257479 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id B7D9FC77B7A for ; Fri, 26 May 2023 23:46:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:Cc:To:From:Subject:References: Mime-Version:Message-Id:In-Reply-To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=eObbOq/ncQgHEmyLKAHHkCSOblp4P2VCPvSbM2aCKB8=; b=qak+Y6JFFVO4WzkjBEzKW+F7A6 O0yCDX0pPOMQt6/N9+xkX9JKkwgr7G2acNvUWWJxwPfGVbGyZ8BowfoSBWkEky7Rr0UesN8ZE+1sk NgDhQUdj3tRdFpTOIusV2OqddfVRTAA+waprAHT3pjBeMmaSJwWDYft6wyZkNvSgXxku2yrIbYciw IPdQhyHoM910REsHTJiQKuJf+QiVjc92+p51y5eNFO+duy4It9DATzkyVQgtHqxJ6Jn74rAMeLP4s kgpU8qx+fBWm502RVMu+qvARrpIkcTFlPU2i0V4LtT0kRNidd/Lrt6Yk3FJNFPmvw7vzwNHvb3nYA WkKYF/1A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1q2h82-004L6z-3C; Fri, 26 May 2023 23:45:50 +0000 Received: from mail-yb1-xb49.google.com ([2607:f8b0:4864:20::b49]) by bombadil.infradead.org with esmtps (Exim 4.96 #2 (Red Hat Linux)) id 1q2h7A-004KXD-2L for linux-arm-kernel@lists.infradead.org; Fri, 26 May 2023 23:44:58 +0000 Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-bad06cc7fb7so2973481276.3 for ; Fri, 26 May 2023 16:44:55 -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=QUPyhvOQVKgVI0WgSxytJ5CnBBf38hlZ3LDDqScS9iHlQtjyQcBRHEdn9twu5VgDf8 vKC+Mh9B0/DwtX8qKFFiHPSmnbbtsnZafacYo9ndm/zckmZf78s2kzWnSUHYUvabkz4q newXTyNeQngSco4xMtWlyJI8jLZqoiwPTo9fiBRXETCpepYkvgclQwymsGdNliCE/zqg 5DgTjPCUb0lrC8Qezee/dhl140WDGpYVQT1AgKFh7GuIxXXhClOvYOfaJIyvKlV0Xl40 +Cnf4qQdH6lDcAwBtKUcRxgQVGZSrKV6kPmRjJW8PaySu6D711iQLPXiei8BsoZS4XEu ZsEQ== X-Gm-Message-State: AC+VfDyXfk+NpBS4DcxesjmfM1/SFMJwbdWzh+piNsKrMJFibMbid1zb 9rIpyFnO2UbeYMhf+KC9kwGvPEFKsqc= 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230526_164456_801946_815E572C X-CRM114-Status: GOOD ( 13.59 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.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) {