From patchwork Fri Oct 23 16:30:24 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 11854009 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE0A5C55179 for ; Fri, 23 Oct 2020 16:31:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 589C821D47 for ; Fri, 23 Oct 2020 16:31:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="i2pDy0AX" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751659AbgJWQbD (ORCPT ); Fri, 23 Oct 2020 12:31:03 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:21722 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751438AbgJWQas (ORCPT ); Fri, 23 Oct 2020 12:30:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603470647; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=2r6z2eq2n8RapzH3Hc0CANhd1X+6+VQ1WVVzaGN7U3M=; b=i2pDy0AXIXNYKUTI6fMUKa9+dq9sbzTWBlKjEdXf56YqHO7c5UGe8ypdpBM5WZ/q65r1Uz 2Hi5zibR4owGMn7hRrV04xbAsDYVFVFKBnh02fKFTZarnjPMmtw0KIFIl7YlbPTxLv+VIj 28NlC+ENe7cdOslUj2yoffvDb7GqSko= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-275-RCsahkEeOdaZ4_LF-Vm3WA-1; Fri, 23 Oct 2020 12:30:44 -0400 X-MC-Unique: RCsahkEeOdaZ4_LF-Vm3WA-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3608C10309BB; Fri, 23 Oct 2020 16:30:43 +0000 (UTC) Received: from virtlab701.virt.lab.eng.bos.redhat.com (virtlab701.virt.lab.eng.bos.redhat.com [10.19.152.228]) by smtp.corp.redhat.com (Postfix) with ESMTP id C6CE09CBC8; Fri, 23 Oct 2020 16:30:42 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: bgardon@google.com Subject: [PATCH 22/22] kvm: x86/mmu: NX largepage recovery for TDP MMU Date: Fri, 23 Oct 2020 12:30:24 -0400 Message-Id: <20201023163024.2765558-23-pbonzini@redhat.com> In-Reply-To: <20201023163024.2765558-1-pbonzini@redhat.com> References: <20201023163024.2765558-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org From: Ben Gardon When KVM maps a largepage backed region at a lower level in order to make it executable (i.e. NX large page shattering), it reduces the TLB performance of that region. In order to avoid making this degradation permanent, KVM must periodically reclaim shattered NX largepages by zapping them and allowing them to be rebuilt in the page fault handler. With this patch, the TDP MMU does not respect KVM's rate limiting on reclaim. It traverses the entire TDP structure every time. This will be addressed in a future patch. Tested by running kvm-unit-tests and KVM selftests on an Intel Haswell machine. This series introduced no new failures. This series can be viewed in Gerrit at: https://linux-review.googlesource.com/c/virt/kvm/kvm/+/2538 Signed-off-by: Ben Gardon Message-Id: <20201014182700.2888246-21-bgardon@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/mmu/mmu.c | 13 +++++++++---- arch/x86/kvm/mmu/mmu_internal.h | 3 +++ arch/x86/kvm/mmu/tdp_mmu.c | 6 ++++++ 3 files changed, 18 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 7b52fa1f01b0..17587f496ec7 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -776,7 +776,7 @@ static void account_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) kvm_mmu_gfn_disallow_lpage(slot, gfn); } -static void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) +void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) { if (sp->lpage_disallowed) return; @@ -804,7 +804,7 @@ static void unaccount_shadowed(struct kvm *kvm, struct kvm_mmu_page *sp) kvm_mmu_gfn_allow_lpage(slot, gfn); } -static void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) +void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) { --kvm->stat.nx_lpage_splits; sp->lpage_disallowed = false; @@ -5988,8 +5988,13 @@ static void kvm_recover_nx_lpages(struct kvm *kvm) struct kvm_mmu_page, lpage_disallowed_link); WARN_ON_ONCE(!sp->lpage_disallowed); - kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); - WARN_ON_ONCE(sp->lpage_disallowed); + if (sp->tdp_mmu_page) + kvm_tdp_mmu_zap_gfn_range(kvm, sp->gfn, + sp->gfn + KVM_PAGES_PER_HPAGE(sp->role.level)); + else { + kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list); + WARN_ON_ONCE(sp->lpage_disallowed); + } if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { kvm_mmu_commit_zap_page(kvm, &invalid_list); diff --git a/arch/x86/kvm/mmu/mmu_internal.h b/arch/x86/kvm/mmu/mmu_internal.h index 6db40ea85974..bfc6389edc28 100644 --- a/arch/x86/kvm/mmu/mmu_internal.h +++ b/arch/x86/kvm/mmu/mmu_internal.h @@ -143,4 +143,7 @@ bool is_nx_huge_page_enabled(void); void *mmu_memory_cache_alloc(struct kvm_mmu_memory_cache *mc); +void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp); +void unaccount_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp); + #endif /* __KVM_X86_MMU_INTERNAL_H */ diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 5158d02b8925..e246d71b8ea2 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -273,6 +273,9 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn, list_del(&sp->link); + if (sp->lpage_disallowed) + unaccount_huge_nx_page(kvm, sp); + for (i = 0; i < PT64_ENT_PER_PAGE; i++) { old_child_spte = READ_ONCE(*(pt + i)); WRITE_ONCE(*(pt + i), 0); @@ -571,6 +574,9 @@ int kvm_tdp_mmu_map(struct kvm_vcpu *vcpu, gpa_t gpa, u32 error_code, !shadow_accessed_mask); trace_kvm_mmu_get_page(sp, true); + if (huge_page_disallowed && req_level >= iter.level) + account_huge_nx_page(vcpu->kvm, sp); + tdp_mmu_set_spte(vcpu->kvm, &iter, new_spte); } }