From nobody Tue Apr 7 07:05:48 2026 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 8FF84ECAAA1 for ; Tue, 30 Aug 2022 23:55:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230455AbiH3Xzr (ORCPT ); Tue, 30 Aug 2022 19:55:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51778 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230093AbiH3Xzm (ORCPT ); Tue, 30 Aug 2022 19:55:42 -0400 Received: from mail-pl1-x64a.google.com (mail-pl1-x64a.google.com [IPv6:2607:f8b0:4864:20::64a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9984D2ED5A for ; Tue, 30 Aug 2022 16:55:41 -0700 (PDT) Received: by mail-pl1-x64a.google.com with SMTP id s8-20020a170902ea0800b00172e456031eso8776762plg.3 for ; Tue, 30 Aug 2022 16:55:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc; bh=KwSYCZerlx8jq2QaoSW9rJT1jqCtPnDeeiOJE8jfST4=; b=BPH+iO6gDGCsp2Wcx1LYWuE/INfoeSg5h3VFyT2+38gryYDiRQNbYYVwlMT78ungxP uhH+zRrer8VCaDfUCOCZIBNmaRpGl8JFqhjto1VWg3595CY+538Oa5oLaTTGSZUOcTrx QmvyynMrgDUdcIUJAcBzCpeO9UY3gTlHOAfaFOQD9qfZr2BxPj/X7k0u36MGUUwFLb/D 3WJmTeRSqrkAK7oOeT0dGuQWP8LbfSWn8mXsflZgNJzq3/hGQ3Bx7/Qh90pQ0vUwCZt7 pl0QmujrSQkoPGrx/eThrTz9cTK3ObEIsit1R1QXl2WXj2YSj+wze22tC2CAXttiyjYT XjoA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc; bh=KwSYCZerlx8jq2QaoSW9rJT1jqCtPnDeeiOJE8jfST4=; b=4sms1aO8Vbv/KiH/fH8mXkWnKzHR//stWTZxlb/UMwvDUPODKB0tfP8R93sovt0qII 9y2J1Z1oIe/kSe3rs8GbmQ5GN2XCKrK1b+U01bukBm3ybgjvIBO41lmeOeOsXMynevSj WM1oWgIyd3GOFYcQ3CYM5zk/nyne1FdtVSkDAnHY4FH7WiOpbKDhpUmNDJScK6Tf8ium 6gnzb50OX1xxcPcUAiPKQMagfxkNIniyKuCMhyStE7SnL4+TuZc4OkxuvXEneyxJkDAX /LHEG/BiRE8QB8sMsUkK0ocVPYeHpOMTY/Wo+qxDlO5PtSo73EB0EFzesyeFm2Uw0VKO 5QGA== X-Gm-Message-State: ACgBeo2vv6TjIBaHjZ7Q0U0xXZ09CRtX+lLXcq1TKmU/OR3Zls1JFZ3J on8Xq1VDxMwtzUIAqoEukuwevf2NHhg= X-Google-Smtp-Source: AA6agR6Gceek7om6pgblzSZOyMYq2EfiLWTCKia41sXQbONpjnXz30oLCnehC/Cob4rJMGMpKrHB2I3lntA= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a62:5ec6:0:b0:538:3aa:7fe5 with SMTP id s189-20020a625ec6000000b0053803aa7fe5mr16255558pfb.73.1661903741190; Tue, 30 Aug 2022 16:55:41 -0700 (PDT) Reply-To: Sean Christopherson Date: Tue, 30 Aug 2022 23:55:29 +0000 In-Reply-To: <20220830235537.4004585-1-seanjc@google.com> Mime-Version: 1.0 References: <20220830235537.4004585-1-seanjc@google.com> X-Mailer: git-send-email 2.37.2.672.g94769d06f0-goog Message-ID: <20220830235537.4004585-2-seanjc@google.com> Subject: [PATCH v4 1/9] KVM: x86/mmu: Bug the VM if KVM attempts to double count an NX huge page From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, David Matlack , Mingwei Zhang , Yan Zhao , Ben Gardon Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" WARN and kill the VM if KVM attempts to double count an NX huge page, i.e. attempts to re-tag a shadow page with "NX huge page disallowed". KVM does NX huge page accounting only when linking a new shadow page, and it should be impossible for a new shadow page to be already accounted. E.g. even in the TDP MMU case, where vCPUs can race to install a new shadow page, only the "winner" will account the installed page. Kill the VM instead of continuing on as either KVM has an egregious bug, e.g. didn't zero-initialize the data, or there's host data corruption, in which carrying on is dangerous, e.g. could cause silent data corruption in the guest. Reported-by: David Matlack Signed-off-by: Sean Christopherson Reviewed-by: Mingwei Zhang --- arch/x86/kvm/mmu/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 32b60a6b83bd..74afee3f2476 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -804,7 +804,7 @@ static void account_shadowed(struct kvm *kvm, struct kv= m_mmu_page *sp) =20 void account_huge_nx_page(struct kvm *kvm, struct kvm_mmu_page *sp) { - if (sp->lpage_disallowed) + if (KVM_BUG_ON(sp->lpage_disallowed, kvm)) return; =20 ++kvm->stat.nx_lpage_splits; --=20 2.37.2.672.g94769d06f0-goog