From patchwork Thu Mar 3 19:38:18 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 12767994 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 11962C433F5 for ; Thu, 3 Mar 2022 19:39:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236055AbiCCTjv (ORCPT ); Thu, 3 Mar 2022 14:39:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58530 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236006AbiCCTjl (ORCPT ); Thu, 3 Mar 2022 14:39:41 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 9BC5165D3C for ; Thu, 3 Mar 2022 11:38:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1646336334; 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=zZ4UIIxhpJEYvaQqiL3cf7FKEY9UCRRYhOm/du6iaY8=; b=SjWmrN20jg2PJss3B2wxF/6GSt/7N7JeP1YobrjgEMGPj+NoUY1sbXfi4IA57tdGafi30Z BBdYVLEZp9SuYq5dmHFVQwm/SZ8w13odTCK1sSiayWoqcSU1gl8Quk3pK8muObiDAP4JF3 dsvcDkeX1CFYFo2wEvXrZGrQS+MAr2c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-608-GzRa4kH9Of-IumONNbTYsQ-1; Thu, 03 Mar 2022 14:38:51 -0500 X-MC-Unique: GzRa4kH9Of-IumONNbTYsQ-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 414DF1006AA5; Thu, 3 Mar 2022 19:38:50 +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 6E9B75E267; Thu, 3 Mar 2022 19:38:49 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , David Hildenbrand , David Matlack , Ben Gardon , Mingwei Zhang Subject: [PATCH v4 06/30] KVM: x86/mmu: only perform eager page splitting on valid roots Date: Thu, 3 Mar 2022 14:38:18 -0500 Message-Id: <20220303193842.370645-7-pbonzini@redhat.com> In-Reply-To: <20220303193842.370645-1-pbonzini@redhat.com> References: <20220303193842.370645-1-pbonzini@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Eager page splitting is an optimization; it does not have to be performed on invalid roots. It is also the only case in which a reader might acquire a reference to an invalid root, so after this change we know that readers will skip both dying and invalid roots. Signed-off-by: Paolo Bonzini Reviewed-by: Sean Christopherson --- arch/x86/kvm/mmu/tdp_mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 30424fbceb5f..d39593b9ac9e 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1464,7 +1464,7 @@ void kvm_tdp_mmu_try_split_huge_pages(struct kvm *kvm, kvm_lockdep_assert_mmu_lock_held(kvm, shared); - for_each_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, shared) { + for_each_valid_tdp_mmu_root_yield_safe(kvm, root, slot->as_id, shared) { r = tdp_mmu_split_huge_pages_root(kvm, root, start, end, target_level, shared); if (r) { kvm_tdp_mmu_put_root(kvm, root, shared);