From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6B30A2E7380 for ; Thu, 18 Jun 2026 18:56:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781809004; cv=none; b=SxFe8HMxChyZbtJ9SkEPBkFqPtLBsAnbHokFyKOYwByV5t8Rh1Gl62tMVxyHv9nab+zE6rP82WXRYausXKOMayVXB7ArWFUu7oEPE4bqZQjmsboyicLlitO4TjdLQ1Moz79X26zu6tbOj6wGQVyQFvMpjF6NCUbK9k6qZw6Kbu8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781809004; c=relaxed/simple; bh=k7pEB1TrJXrtJVXWHb/y4s/VECamhLF0DoS0yfjjuPw=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=jpowEWGPiS/CnGdNptM0ej1XinH0vRrW7m6ixOPNI9GCJzrgzp0/ynY0zxlHiJRA56CorF/N2zP6mVV0nswUt8AAYytvnydozvVgOFFMHtdPCTMle5rfwnFeMT1cUN8w88ZAhHJew0wTXJGVXK2yKpSOI7nnkxFjPp5rCeKP8xA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=R9LcPU4a; arc=none smtp.client-ip=209.85.215.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="R9LcPU4a" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-c898897816fso688951a12.1 for ; Thu, 18 Jun 2026 11:56:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1781809003; x=1782413803; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:reply-to:from:to:cc :subject:date:message-id:reply-to; bh=BpZX4un/aVSFnNpO1jcVNhucJmMh4JR8uc7m+5+/1dQ=; b=R9LcPU4aqSCHDVzPew1wF1FZ2pJJl7v/ynnmL5xWKcmFbooPtmOnABf6O2ZTujiXOr zNRlmnXqyLR14c1gX57TX+Z1pLMEaMSbNpIWNHu4ecaS2MpjjZ6vlCp7WSFczgt+PzZ8 IQpHTCrRD4258NttHYjeDKd7P3MPJPBtUKbkHv1QflB0ujx0hfMr2GVTQJoW8lL5Lnfv LlJ4esVURaBXemibuIwKalXIwYPVExBJPZLf0e4iiFhaa00lm/r4L6vuq5HEPJUxgVRD Jaa1t2ffNHQVskS365eQ3UlkLrnxhBGypSSOPmDu4QnIQMRTIn0Ayt/jK/OhMk16Yq5W /oww== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781809003; x=1782413803; h=cc:to:from:subject:message-id:mime-version:date:reply-to :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=BpZX4un/aVSFnNpO1jcVNhucJmMh4JR8uc7m+5+/1dQ=; b=GydmSaLjCUmpf8Q/pKNradmwJUdXk1IIqlltIG62Gg0dIyjeBrKrNnOSGnRnR03CeJ F/n8x9WuyKRxrr4d5OBoonsvX2xF6k5/aiIMo8I8OVvoTUq/5GiC9fEfTx1XhQLd9rA9 2hsvPuzXpZzSn+WUiDl01J+rrzO/iVeXR7fspo6kFPpOdty4NU21rhkR+kySyK9mfYyy r/Gmg+tni0IpjKeRMXA2Dqu4O+YgeMc5jma/StSOLLr0Ou3n9/Q23/MSeLr2HZLxk6aU TBdC8mNUlsTyBMXWEXsR/+WuqDT3NKfDU0dOnYURG7WzkyYignTrc5L7O8sQ7wcEBuiV KAqg== X-Forwarded-Encrypted: i=1; AFNElJ9pzdZrkPs9mv28JgusRuI5Zo4LnyvayWty6UD9NSm/wbXer2PbZPFiAAqSL/T3BQg8mxvhf1jQGvaUB0M=@vger.kernel.org X-Gm-Message-State: AOJu0YymDrEHTGxytdIOUyblaWr/5RFd3oZdZj2thPif25mqf8+kYbeT Pfp4ujQDAgivWmMsLzatp6gateO3GedMV96FOn1xCyRhAELcBiz0S8zv6R/5yFIA5NgtGo2gaci lvTfGKw== X-Received: from pfob8.prod.google.com ([2002:aa7:8708:0:b0:842:47f8:d51d]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:1916:b0:842:5b63:610f with SMTP id d2e1a72fcca58-845507a9ea7mr165386b3a.4.1781809002646; Thu, 18 Jun 2026 11:56:42 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 18 Jun 2026 11:56:41 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.55.0.rc0.738.g0c8ab3ebcc-goog Message-ID: <20260618185641.2022368-1-seanjc@google.com> Subject: [PATCH] KVM: x86/mmu: Bug the VM, not the host kernel, if KVM write-protects upper SPTEs From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" WARN and terminate the VM if KVM attempts to write-protect non-leaf SPTEs instead of bugging the host kernel, as there is no reason to bring down the entire host. Even termininating the VM is likely overkill, but in theory a missed write could corrupt guest memory, so play it safe. Signed-off-by: Sean Christopherson --- arch/x86/kvm/mmu/tdp_mmu.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index 5b3041138301..c1cbae65d239 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -1410,9 +1410,10 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, u64 new_spte; bool spte_set = false; - rcu_read_lock(); + if (KVM_BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL, kvm)) + return false; - BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL); + rcu_read_lock(); for_each_tdp_pte_min_level(iter, kvm, root, min_level, start, end) { retry: @@ -1844,7 +1845,8 @@ static bool write_protect_gfn(struct kvm *kvm, struct kvm_mmu_page *root, u64 new_spte; bool spte_set = false; - BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL); + if (KVM_BUG_ON(min_level > KVM_MAX_HUGEPAGE_LEVEL, kvm)) + return false; rcu_read_lock(); base-commit: 9d4853b044beefa21c4ee3e18c40653601a64ced -- 2.55.0.rc0.738.g0c8ab3ebcc-goog