From mboxrd@z Thu Jan 1 00:00:00 1970 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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 C8369C48BE5 for ; Tue, 22 Jun 2021 07:25:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB3DE61026 for ; Tue, 22 Jun 2021 07:25:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230160AbhFVH1P (ORCPT ); Tue, 22 Jun 2021 03:27:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229789AbhFVH1N (ORCPT ); Tue, 22 Jun 2021 03:27:13 -0400 Received: from mail-qk1-x749.google.com (mail-qk1-x749.google.com [IPv6:2607:f8b0:4864:20::749]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A13EC061756 for ; Tue, 22 Jun 2021 00:24:58 -0700 (PDT) Received: by mail-qk1-x749.google.com with SMTP id o189-20020a378cc60000b02903b2ccd94ea1so438560qkd.19 for ; Tue, 22 Jun 2021 00:24:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:message-id:mime-version:subject:from:to:cc; bh=BD4lpbPgIYJoxQKzEzU6bqCGaw9muIxLDsW7Q3v9h6k=; b=esL8Wgp1T4BxTy0TqGV+jDA5F57PodHBxA6bFbaWmKGQPwRDwaBqhB0QD8a+AEzzIc CbAPXjSfXR7KaKvl4yJNzj6r4ti/Z4dwYWc/Ji66CpEuJpXhag2VJwV5oeLdRR1fsBM9 H9ojzo6rqek2pOe21/j8o60sgq6oMGy9N4KU11E7YOJxWGpGOefyDp7vyuxE2Pn3WSn3 iSspCTit8s7i4G5DSB0YEtcofXbLo5DVz2XzRWcFAAIts9nwy9Gw/tsZ0YVe4WftZ/pc Cs+9wXAg9Xf1n9ODTt4b4BhJGBqeyyFtgXhv1yZNSElx8fX+dozETAipwHmbjTOkF5HY KU8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:message-id:mime-version:subject :from:to:cc; bh=BD4lpbPgIYJoxQKzEzU6bqCGaw9muIxLDsW7Q3v9h6k=; b=qbZ1cVm8zKjHFJ7aY+8e0xPvPUF19v5u0aVRBYKLS15Rb3YyeOVGnkNbDokfaGtOTQ tgBlyeHHLOtMb2YsSBuyj3uGl+nFYOoZ0Ch8gHDr93BaWSmN1IzBxBfD6D+hVvy/zum6 A38JDHZ4PJoCoFs+3hoOS1bI3hXIcsTrmwz3WOe4W+Jh+Y9FpWvahZHsEJTYDzqFg5xe H1GodcuwJMkXprROYXaBnsTOaN6wilpmYe6d1Gj4sb9KnKRxEclYv+p35xAlw4PXe1Jq f08ZCldqMV5158IF0blngrJOzmMSNoK5Bg06eLzoBQXNYHTuF9GfZ99HcMPgCBJquN8m e1cQ== X-Gm-Message-State: AOAM532xyhOZnQyr7n9J15ylzxZGPyPrevvrvOharw3kdACvYqVrK0hN vM70PU1oNH5OiV4CUnM/rJ/NwDJAN7A= X-Google-Smtp-Source: ABdhPJyJj8tlqT95Jr5UGXnlzkZJA+EWDiIPs1qaYV1oUrDbRZ4ZtoVYOfZpGDiXR7pjcX8YU+BBsU153rs= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:f:10:5722:92ce:361f:3832]) (user=seanjc job=sendgmr) by 2002:a25:aba7:: with SMTP id v36mr2898354ybi.124.1624346697403; Tue, 22 Jun 2021 00:24:57 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 22 Jun 2021 00:24:54 -0700 Message-Id: <20210622072454.3449146-1-seanjc@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.288.g62a8d224e6-goog Subject: [PATCH] KVM: x86/mmu: Don't WARN on a NULL shadow page in TDP MMU check From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Treat a NULL shadow page in the "is a TDP MMU" check as valid, non-TDP root. KVM uses a "direct" PAE paging MMU when TDP is disabled and the guest is running with paging disabled. In that case, root_hpa points at the pae_root page (of which only 32 bytes are used), not a standard shadow page, and the WARN fires (a lot). Fixes: 0b873fd7fb53 ("KVM: x86/mmu: Remove redundant is_tdp_mmu_enabled check") Cc: David Matlack Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/tdp_mmu.h | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.h b/arch/x86/kvm/mmu/tdp_mmu.h index b981a044ab55..1cae4485b3bc 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.h +++ b/arch/x86/kvm/mmu/tdp_mmu.h @@ -94,11 +94,13 @@ static inline bool is_tdp_mmu(struct kvm_mmu *mmu) if (WARN_ON(!VALID_PAGE(hpa))) return false; + /* + * A NULL shadow page is legal when shadowing a non-paging guest with + * PAE paging, as the MMU will be direct with root_hpa pointing at the + * pae_root page, not a shadow page. + */ sp = to_shadow_page(hpa); - if (WARN_ON(!sp)) - return false; - - return is_tdp_mmu_page(sp) && sp->root_count; + return sp && is_tdp_mmu_page(sp) && sp->root_count; } #else static inline bool kvm_mmu_init_tdp_mmu(struct kvm *kvm) { return false; } -- 2.32.0.288.g62a8d224e6-goog