From patchwork Tue Apr 5 07:29:32 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 557352 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 7A0E8C433EF for ; Tue, 5 Apr 2022 10:17:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353744AbiDEKJJ (ORCPT ); Tue, 5 Apr 2022 06:09:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59666 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345347AbiDEJW3 (ORCPT ); Tue, 5 Apr 2022 05:22:29 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0A0F47AE4; Tue, 5 Apr 2022 02:10:38 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7DEF161527; Tue, 5 Apr 2022 09:10:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FCE4C385A0; Tue, 5 Apr 2022 09:10:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649149837; bh=FwQBUKInjP4jnvxbqXA+7tsKrzdHs2KgsX0dQYJAh1Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uBZX53MTpIwJ0bqRbcnr43MgQHs8bygVwgjJXLIK5sSb89rzi/Zq7nZGYHYEMHhuH 7k5B3Ol+msfWkOwW9LfjJA2F6GMp0xVVjrTwmt4nUYHi8edTYhw1egAuBv0737DFrE /knp4++mCbQqedZyC2Wz/jGiNwYRjydc96GePiEQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.16 0859/1017] KVM: x86/mmu: Move "invalid" check out of kvm_tdp_mmu_get_root() Date: Tue, 5 Apr 2022 09:29:32 +0200 Message-Id: <20220405070419.732710256@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sean Christopherson commit 04dc4e6ce274fa729feda32aa957b27388a3870c upstream. Move the check for an invalid root out of kvm_tdp_mmu_get_root() and into the one place it actually matters, tdp_mmu_next_root(), as the other user already has an implicit validity check. A future bug fix will need to get references to invalid roots to honor mmu_notifier requests; there's no point in forcing what will be a common path to open code getting a reference to a root. No functional change intended. Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20211215011557.399940-3-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu/tdp_mmu.c | 12 ++++++++++-- arch/x86/kvm/mmu/tdp_mmu.h | 3 --- 2 files changed, 10 insertions(+), 5 deletions(-) --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -121,9 +121,14 @@ static struct kvm_mmu_page *tdp_mmu_next next_root = list_first_or_null_rcu(&kvm->arch.tdp_mmu_roots, typeof(*next_root), link); - while (next_root && !kvm_tdp_mmu_get_root(kvm, next_root)) + while (next_root) { + if (!next_root->role.invalid && + kvm_tdp_mmu_get_root(kvm, next_root)) + break; + next_root = list_next_or_null_rcu(&kvm->arch.tdp_mmu_roots, &next_root->link, typeof(*next_root), link); + } rcu_read_unlock(); @@ -200,7 +205,10 @@ hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(stru role = page_role_for_level(vcpu, vcpu->arch.mmu->shadow_root_level); - /* Check for an existing root before allocating a new one. */ + /* + * Check for an existing root before allocating a new one. Note, the + * role check prevents consuming an invalid root. + */ for_each_tdp_mmu_root(kvm, root, kvm_mmu_role_as_id(role)) { if (root->role.word == role.word && kvm_tdp_mmu_get_root(kvm, root)) --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -10,9 +10,6 @@ hpa_t kvm_tdp_mmu_get_vcpu_root_hpa(stru __must_check static inline bool kvm_tdp_mmu_get_root(struct kvm *kvm, struct kvm_mmu_page *root) { - if (root->role.invalid) - return false; - return refcount_inc_not_zero(&root->tdp_mmu_root_count); }