From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793819867; b=JA5kVNa0lE+P2UjIg4lGEJorhgg1CFCrYJb61MzR8toRja25tOaaA1DG2ydn9JzW/hwn +TI262tb5K/dMgU9xnK+p+yMZom/lI00wmYwhpZrEpqFE2yNbNbQLOtaBQhKVaveHi8VU OI1yjexddxp+Jq/rnL9u7jn1bKeWqQLA5yadSdpIiSGGjtEsztv5ugj09hqm404XO52e/ vxQdPrh41af+q6ef3KNKpfqPA45dEIuEIlRdPBmw+jEh3UY0WOdg0OjAzEgZkiWCTTOgo Jco1K1mFg7BxZa0D/dVsvnSTYRtLuqj8xQQvSTcDKOo3Qr7+dz/iJM5j/JvLeiGyfAg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793819867; h=Received:DKIM-Signature:Subject:To:Cc:From:Date:Message-ID: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=4kOs1pNuSHq8iTQKrLOxl9bPqtHgjId4r9Eb5LZ3h7s=; b=b26q6BOxPxSMQ5vSxU0zhFnOu7JU7GjmYf5rjRjL3onMb2xHplNROOWD7gmBCH0+TAdT REcBfTsjQH8PMDnvbOna3FBpyBMFtzX5bdiXaljCpkZJWO6HwSkJk+dxhC10Hngt910CB 0T3+gGIC5MMKCPrC58wuqSKuHcuQ11Chd8BFc9mj2Hh6W6TIXYPBd3Be2Apa2rrv/p2zX b+LufjDQGd03T5CiQ4tDLOOFhMepBK0NGeqmRDsezYWIqHze1RCDC8CjNTKVmwI3xWMod 9G8ZcUh2sz6Sv53TJLcWUF4DORjhYK7VUHUWl/ePTC7UgFBcvvc7OyPgnxIMqiBa8QQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=2Chfcqn2; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E07DA606D81D for ; Wed, 4 Nov 2026 19:17:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=2Chfcqn2 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 812461F00919; Wed, 4 Nov 2026 19:17:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793819866; bh=4kOs1pNuSHq8iTQKrLOxl9bPqtHgjId4r9Eb5LZ3h7s=; h=Subject:To:Cc:From:Date; b=2Chfcqn2GY90I8j9G+KR08SAvMt1NCINzDaOwTzUF22KBInSFzuNRUsfJo5cOpQwe 7levttDsbbKAjJ7FFYv/YWknjvUp2ecH8WpbdOaD3b/iMTxJ8D8AZ8YS5w84TltTWA B52C6s9QTaTGPzOpBJEmYMe6PU3h+BptvU+4yWm8= Subject: FAILED: patch "[PATCH] KVM: nSVM: Reject KVM_SET_NESTED_STATE if L1 has EFER.LMA=1" failed to apply to 5.15-stable tree To: seanjc@google.com,fane@google.com,yosry@kernel.org Cc: From: Date: Wed, 04 Nov 2026 14:17:39 -0500 Message-ID: <2026110439-traitor-grape-fda1@gregkh> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 5dc500a354cc8e109df678076ae3488094649468 # git commit -s git send-email --to '' --in-reply-to '2026110439-traitor-grape-fda1@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..' Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 5dc500a354cc8e109df678076ae3488094649468 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 2 Sep 2026 16:20:24 -0700 Subject: [PATCH] KVM: nSVM: Reject KVM_SET_NESTED_STATE if L1 has EFER.LMA=1 && EFER.LME=0 Reject KVM_SET_NESTED_STATE if the incoming L1 host state has what is effectively an impossible EFER combination of LMA=1 but LME=0, i.e. if the state says long mode is active but not enabled. Unlike VMX, SVM doesn't have an explicit consistent check for the illegal combination; presumably hardware simply ignores EFER.LMA if EFER.LME=0. Unfortunately, KVM doesn't ignore EFER.LMA in this case and consumes the illegal state when constructing the shadow MMU for L2. E.g. if userspace also clears CR4.PAE, then kvm_calc_cpu_role() will compute a role with 4 or 5 levels of paging, but shadow_mmu_init_context() will wire up the MMU to use the paging32 template, which maxes out its levels at 2. Note, the "real badness" is effectively the same as what happened with the nVMX bug fixed by commit 112e66017bff ("KVM: nVMX: add missing consistency checks for CR0 and CR4"). Unfortunately, the sanity check added by commit 72e2fb24a0b0 ("KVM: x86/mmu: Bug the VM if a vCPU ends up in long mode without PAE enabled") doesn't work for this case, since L2 state is active at the time of the page fault, but it's L1 that has the bad state. Fixes: cc440cdad5b7 ("KVM: nSVM: implement KVM_GET_NESTED_STATE and KVM_SET_NESTED_STATE") Cc: stable@vger.kernel.org Cc: Yosry Ahmed Reported-by: Stefan Teodorescu Link: https://patch.msgid.link/20260902232028.2767071-2-seanjc@google.com Signed-off-by: Sean Christopherson diff --git a/arch/x86/kvm/svm/nested.c b/arch/x86/kvm/svm/nested.c index 73f37b050d0a..49fb10ad1f9f 100644 --- a/arch/x86/kvm/svm/nested.c +++ b/arch/x86/kvm/svm/nested.c @@ -2028,6 +2028,7 @@ static int svm_set_nested_state(struct kvm_vcpu *vcpu, if (!(save->cr0 & X86_CR0_PG) || !(save->cr0 & X86_CR0_PE) || (save->rflags & X86_EFLAGS_VM) || + ((save->efer & EFER_LMA) && !(save->efer & EFER_LME)) || !nested_vmcb_check_save(vcpu, &save_cached, false)) goto out_free;