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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 17735C433EF for ; Mon, 21 Feb 2022 09:29:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349995AbiBUJaG (ORCPT ); Mon, 21 Feb 2022 04:30:06 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:37036 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350236AbiBUJWQ (ORCPT ); Mon, 21 Feb 2022 04:22:16 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CED237BEC; Mon, 21 Feb 2022 01:09:43 -0800 (PST) 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 sin.source.kernel.org (Postfix) with ESMTPS id 8CB12CE0E96; Mon, 21 Feb 2022 09:09:39 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 70534C340F6; Mon, 21 Feb 2022 09:09:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1645434578; bh=gIfNhR54g7OTklTqzjeHb/ybmRQgcuW62HjKCcKfRYU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=iaVtlBJMYwWW8KfE75OSViVUA71g5qnuTlPDCQqU7x3FP3xqp1ObIBvK2ORguTJly tqobhasUSRWMEEm4YsRwggzZpbjBkaYfWKegUymCaAUcu8h1Eyt72mYTb1H0DxZ6gm 5Q+ZSwx57f8RudvARCq3Iz9BsRkuu1AvmYCunu4o= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Maxim Levitsky , Paolo Bonzini Subject: [PATCH 5.15 057/196] KVM: x86: SVM: dont passthrough SMAP/SMEP/PKE bits in !NPT && !gCR0.PG case Date: Mon, 21 Feb 2022 09:48:09 +0100 Message-Id: <20220221084932.839293131@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220221084930.872957717@linuxfoundation.org> References: <20220221084930.872957717@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Maxim Levitsky commit c53bbe2145f51d3bc0438c2db02e737b9b598bf3 upstream. When the guest doesn't enable paging, and NPT/EPT is disabled, we use guest't paging CR3's as KVM's shadow paging pointer and we are technically in direct mode as if we were to use NPT/EPT. In direct mode we create SPTEs with user mode permissions because usually in the direct mode the NPT/EPT doesn't need to restrict access based on guest CPL (there are MBE/GMET extenstions for that but KVM doesn't use them). In this special "use guest paging as direct" mode however, and if CR4.SMAP/CR4.SMEP are enabled, that will make the CPU fault on each access and KVM will enter endless loop of page faults. Since page protection doesn't have any meaning in !PG case, just don't passthrough these bits. The fix is the same as was done for VMX in commit: commit 656ec4a4928a ("KVM: VMX: fix SMEP and SMAP without EPT") This fixes the boot of windows 10 without NPT for good. (Without this patch, BSP boots, but APs were stuck in endless loop of page faults, causing the VM boot with 1 CPU) Signed-off-by: Maxim Levitsky Cc: stable@vger.kernel.org Message-Id: <20220207155447.840194-2-mlevitsk@redhat.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/svm/svm.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -1727,6 +1727,7 @@ void svm_set_cr0(struct kvm_vcpu *vcpu, { struct vcpu_svm *svm = to_svm(vcpu); u64 hcr0 = cr0; + bool old_paging = is_paging(vcpu); #ifdef CONFIG_X86_64 if (vcpu->arch.efer & EFER_LME && !vcpu->arch.guest_state_protected) { @@ -1743,8 +1744,11 @@ void svm_set_cr0(struct kvm_vcpu *vcpu, #endif vcpu->arch.cr0 = cr0; - if (!npt_enabled) + if (!npt_enabled) { hcr0 |= X86_CR0_PG | X86_CR0_WP; + if (old_paging != is_paging(vcpu)) + svm_set_cr4(vcpu, kvm_read_cr4(vcpu)); + } /* * re-enable caching here because the QEMU bios @@ -1788,8 +1792,12 @@ void svm_set_cr4(struct kvm_vcpu *vcpu, svm_flush_tlb(vcpu); vcpu->arch.cr4 = cr4; - if (!npt_enabled) + if (!npt_enabled) { cr4 |= X86_CR4_PAE; + + if (!is_paging(vcpu)) + cr4 &= ~(X86_CR4_SMEP | X86_CR4_SMAP | X86_CR4_PKE); + } cr4 |= host_cr4_mce; to_svm(vcpu)->vmcb->save.cr4 = cr4; vmcb_mark_dirty(to_svm(vcpu)->vmcb, VMCB_CR);