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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 DAC8CC38A2B for ; Fri, 17 Apr 2020 16:38:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B724620780 for ; Fri, 17 Apr 2020 16:38:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="UeaX/l/2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726709AbgDQQi4 (ORCPT ); Fri, 17 Apr 2020 12:38:56 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:51720 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726390AbgDQQis (ORCPT ); Fri, 17 Apr 2020 12:38:48 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1587141527; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=J7/+hu9xA4V/kb8irjtGYa6Qo9G4EJkKAhc6pSJfI0o=; b=UeaX/l/20GO3JBwzsoQIi8onTZ+diuiktMtOtbfHrMJ7O6KCyUtL7hbH4K/0jYba9P9I2+ r5hWcAb7RKeYk3vyfjcGxRjVAtr62wnJ+I38mUcqJdat3+K8zfjRXlZIAra17Tx7hgFtyb p/nunvavmPec9WpdzyEl4z1jrLcReCg= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-390-wpnn2rtMOUa9iepu47f1rA-1; Fri, 17 Apr 2020 12:38:45 -0400 X-MC-Unique: wpnn2rtMOUa9iepu47f1rA-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 84C2E8024E2; Fri, 17 Apr 2020 16:38:44 +0000 (UTC) Received: from virtlab511.virt.lab.eng.bos.redhat.com (virtlab511.virt.lab.eng.bos.redhat.com [10.19.152.198]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1846C5DA84; Fri, 17 Apr 2020 16:38:44 +0000 (UTC) From: Paolo Bonzini To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org Cc: Sean Christopherson , stable@vger.kernel.org Subject: [PATCH 1/2] KVM: SVM: avoid infinite loop on NPF from bad address Date: Fri, 17 Apr 2020 12:38:42 -0400 Message-Id: <20200417163843.71624-2-pbonzini@redhat.com> In-Reply-To: <20200417163843.71624-1-pbonzini@redhat.com> References: <20200417163843.71624-1-pbonzini@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When a nested page fault is taken from an address that does not have a memslot associated to it, kvm_mmu_do_page_fault returns RET_PF_EMULATE (via mmu_set_spte) and kvm_mmu_page_fault then invokes svm_need_emulation_on_page_fault. The default answer there is to return false, but in this case this just causes the page fault to be retried ad libitum. Since this is not a fast path, and the only other case where it is taken is an erratum, just stick a kvm_vcpu_gfn_to_memslot check in there to detect the common case where the erratum is not happening. This fixes an infinite loop in the new set_memory_region_test. Fixes: 05d5a4863525 ("KVM: SVM: Workaround errata#1096 (insn_len maybe zero on SMAP violation)") Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini --- arch/x86/kvm/svm/svm.c | 7 +++++++ virt/kvm/kvm_main.c | 1 + 2 files changed, 8 insertions(+) diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index a91e397d6750..c86f7278509b 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -3837,6 +3837,13 @@ static bool svm_need_emulation_on_page_fault(struct kvm_vcpu *vcpu) bool smap = cr4 & X86_CR4_SMAP; bool is_user = svm_get_cpl(vcpu) == 3; + /* + * If RIP is invalid, go ahead with emulation which will cause an + * internal error exit. + */ + if (!kvm_vcpu_gfn_to_memslot(vcpu, kvm_rip_read(vcpu) >> PAGE_SHIFT)) + return true; + /* * Detect and workaround Errata 1096 Fam_17h_00_0Fh. * diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index e2f60e313c87..e7436d054305 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -1602,6 +1602,7 @@ struct kvm_memory_slot *kvm_vcpu_gfn_to_memslot(struct kvm_vcpu *vcpu, gfn_t gfn { return __gfn_to_memslot(kvm_vcpu_memslots(vcpu), gfn); } +EXPORT_SYMBOL_GPL(kvm_vcpu_gfn_to_memslot); bool kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn) { -- 2.18.2