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=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 D6557C433FF for ; Wed, 14 Aug 2019 13:29:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B237D206C1 for ; Wed, 14 Aug 2019 13:29:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728140AbfHNN3Y (ORCPT ); Wed, 14 Aug 2019 09:29:24 -0400 Received: from mail-wr1-f67.google.com ([209.85.221.67]:43514 "EHLO mail-wr1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727755AbfHNN3Y (ORCPT ); Wed, 14 Aug 2019 09:29:24 -0400 Received: by mail-wr1-f67.google.com with SMTP id y8so5154001wrn.10 for ; Wed, 14 Aug 2019 06:29:22 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Vt6M8evguG8mza7xAGCORpRNGIMSe6MxiCbo5YivOBk=; b=UYGoYC5ppE5KXUoH1bdk8CffqUVC/Mclu4YIcExJOqa/4C4NR0/2HU6weePxYJIuMg V1/q4ZFuEYROY//CwYR8miJDZtM0KektVRGhLXRUlj6bod9PGmJUUcj7j9F/c/D08jRI 0mlK6EW9fGu/MhJXENi8u1T/p3IQZs1hMGjbH6sR6MJBu+hl/ht1RYjcOIS5zT5ZOapT 0iEQCsuKV1vR6RT5HksESYDO47O1i56r+IkYX1D8fVk3h4u1JKVCK5oHT983Hgl9LMQq TeldOhHUDkhtiLC24ueD76dfx7ksF9u6vWeqITEsQf3jE+CptTe2Goa6xqNxb3U8ykSS sUqw== X-Gm-Message-State: APjAAAVKh6D3/4EQSlWFm0kylw+Pr+tpC9B5s+qndZsRPGAYhfj17mii I9nuf6dd6xZdlg+YtZ2mfTm4Is1f3hE= X-Google-Smtp-Source: APXvYqwGUCBvQIFvJWsaQjWF1pIdbcTuoqLxKp8M4Us+qFA7PbNgUf7dCVRKH2NabDANH5yzssaA8g== X-Received: by 2002:adf:fc87:: with SMTP id g7mr48053642wrr.319.1565789362015; Wed, 14 Aug 2019 06:29:22 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:2cae:66cd:dd43:92d9? ([2001:b07:6468:f312:2cae:66cd:dd43:92d9]) by smtp.gmail.com with ESMTPSA id f18sm8245770wrx.85.2019.08.14.06.29.21 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Wed, 14 Aug 2019 06:29:21 -0700 (PDT) Subject: Re: [PATCH] kvm: x86: skip populating logical dest map if apic is not sw enabled To: Bandan Das , kvm Cc: =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= , linux-kernel References: From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: Date: Wed, 14 Aug 2019 15:29:20 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/08/19 05:37, Bandan Das wrote: > > recalculate_apic_map does not santize ldr and it's possible that > multiple bits are set. In that case, a previous valid entry > can potentially be overwritten by an invalid one. > > This condition is hit when booting a 32 bit, >8 CPU, RHEL6 guest and then > triggering a crash to boot a kdump kernel. This is the sequence of > events: > 1. Linux boots in bigsmp mode and enables PhysFlat, however, it still > writes to the LDR which probably will never be used. > 2. However, when booting into kdump, the stale LDR values remain as > they are not cleared by the guest and there isn't a apic reset. > 3. kdump boots with 1 cpu, and uses Logical Destination Mode but the > logical map has been overwritten and points to an inactive vcpu. > > Signed-off-by: Radim Krcmar > Signed-off-by: Bandan Das > --- > arch/x86/kvm/lapic.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c > index 685d17c11461..e904ff06a83d 100644 > --- a/arch/x86/kvm/lapic.c > +++ b/arch/x86/kvm/lapic.c > @@ -216,6 +216,9 @@ static void recalculate_apic_map(struct kvm *kvm) > if (!apic_x2apic_mode(apic) && !new->phys_map[xapic_id]) > new->phys_map[xapic_id] = apic; > > + if (!kvm_apic_sw_enabled(apic)) > + continue; > + > ldr = kvm_lapic_get_reg(apic, APIC_LDR); > > if (apic_x2apic_mode(apic)) { > @@ -258,6 +261,8 @@ static inline void apic_set_spiv(struct kvm_lapic *apic, u32 val) > static_key_slow_dec_deferred(&apic_sw_disabled); > else > static_key_slow_inc(&apic_sw_disabled.key); > + > + recalculate_apic_map(apic->vcpu->kvm); > } > } > > Queued, thanks. Paolo