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=-6.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 6E4A5C433E1 for ; Wed, 8 Jul 2020 09:08:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 45DB62064C for ; Wed, 8 Jul 2020 09:08:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ghPAhjY8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727791AbgGHJIm (ORCPT ); Wed, 8 Jul 2020 05:08:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56452 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726121AbgGHJIm (ORCPT ); Wed, 8 Jul 2020 05:08:42 -0400 Received: from mail-ot1-x344.google.com (mail-ot1-x344.google.com [IPv6:2607:f8b0:4864:20::344]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6C685C08C5DC; Wed, 8 Jul 2020 02:08:42 -0700 (PDT) Received: by mail-ot1-x344.google.com with SMTP id 18so36383568otv.6; Wed, 08 Jul 2020 02:08:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/pO1lbFCUd8JVwU/a/C5IVsUOfyRnCXcTbnllnxeuBc=; b=ghPAhjY89wPTtIb5w/erbhv+0Fu4o6P535grpb4/02l9c5Ecua3V4upA6wSmM9SMx0 xtWAAaSRAjVWDWKsxP32g8hKqpQBeku2BlDUNd13Co4gN0YNetcGkuKRwBg8ctlxkJFo CKAbwXQpXIVLXiYlbWcMgia41QD2185eniFbgyffkSDlej7W96qNLpUtpbdmx0fRmi6k OmIyCZ7PiNSYxyOWFHVkgnYI3YuTzx0M4PwOYnYoRGwmkQyN5VfT2Jw0EfqdKCs8qrBC IZrHUpN6YnhJ7cjEbifPgF3IjB8lZqbAbbiCbKKGbEYe67AlNYAYOPDkwSFDKvx91gWA efRg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/pO1lbFCUd8JVwU/a/C5IVsUOfyRnCXcTbnllnxeuBc=; b=dHAxM8h+Lw3OaBOoovG9gDkVU7igPuDm0CbgWSncrx/dH9V7baU9arFO2Cgatn0ybQ UdEWVSQZsYwwMNOC/e+6XixRLfqj/zvvyzH9WbOuEaAHl2tKAbtosrEozl5ckXUNHHdn L1OyOW1UANpfmsJP0LqfEONsx9XJxf1L7cAkJXLGQrDx40XYLY8OwDdX145CU8XaXAOK FkdclDCNCCv3E3/g01aoDlrAkWvH07l/FATFuWR4ykGYIgcUlGmeBu+6LnK7MLxmL/7P iZB9rc/iLv4rsNfbDPZIDGeS6jM8IFZ/izZEJABnejoB5OAhZUAA8+LYMYi10YQxpV5S zOcA== X-Gm-Message-State: AOAM533p1rGTH++S2YusA1PehNiPyZHJGDAfUsDXEBBgBmzJ5GDRk4rA pw7nLEf2W4rmqZ8JeNttcHSsa4wYhknER4INztlrkg== X-Google-Smtp-Source: ABdhPJzG8uWjy+Qg3xQqO7+HHpcnCYMSI0FRT+Xb0hwMEVHj2JqTVkb2Sl5Z6vYWYiJAD/qPNTNH98MTyENK31IFEss= X-Received: by 2002:a9d:6f0d:: with SMTP id n13mr36728254otq.254.1594199321840; Wed, 08 Jul 2020 02:08:41 -0700 (PDT) MIME-Version: 1.0 References: <20200417163843.71624-1-pbonzini@redhat.com> <20200417163843.71624-2-pbonzini@redhat.com> <57a405b3-6836-83f0-ed97-79f637f7b456@redhat.com> In-Reply-To: <57a405b3-6836-83f0-ed97-79f637f7b456@redhat.com> From: Wanpeng Li Date: Wed, 8 Jul 2020 17:08:31 +0800 Message-ID: Subject: Re: [PATCH 1/2] KVM: SVM: avoid infinite loop on NPF from bad address To: Paolo Bonzini Cc: LKML , kvm , Sean Christopherson , "# v3 . 10+" Content-Type: text/plain; charset="UTF-8" Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Wed, 8 Jul 2020 at 16:38, Paolo Bonzini wrote: > > On 08/07/20 10:17, Wanpeng Li wrote: > > On Sat, 18 Apr 2020 at 00:39, Paolo Bonzini wrote: > >> 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); > > > > This commit incurs the linux guest fails to boot once add --overcommit > > cpu-pm=on or not intercept hlt instruction, any thoughts? > > Can you write a selftest? Actually I don't know what's happening here(why not intercept hlt instruction has associated with this commit), otherwise, it has already been fixed. :) Wanpeng