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 E310CC83F17 for ; Wed, 30 Aug 2023 19:29:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343617AbjH3T3q (ORCPT ); Wed, 30 Aug 2023 15:29:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50752 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245291AbjH3PEd (ORCPT ); Wed, 30 Aug 2023 11:04:33 -0400 Received: from mail-pf1-x434.google.com (mail-pf1-x434.google.com [IPv6:2607:f8b0:4864:20::434]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A29CB1A2; Wed, 30 Aug 2023 08:04:30 -0700 (PDT) Received: by mail-pf1-x434.google.com with SMTP id d2e1a72fcca58-68c3b9f83f4so3363889b3a.2; Wed, 30 Aug 2023 08:04:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1693407870; x=1694012670; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:from:to:cc:subject:date :message-id:reply-to; bh=BY1v90+5NSPW40nepdwawsmQXXDE6gdV3lwX6BIPunA=; b=oGpKHI4gJgY/7X7wqWG36eFW587MvdRbuWCbeCSceD7I7utq+LvwecNsqQVuAHzT99 /XneeomYAkiLo1c3xdtJExCy/jKT9lkmsML8ft+1DdVySCHpvSVSFAbFpm9XRTo0YLHO JnD9relNlHSdPP1rNoKViGiYudgw1JWaKZQt1UeDpKluSSJRGt+fvnNs5fU35BfeVYkX yzBh4tEwZtkD7QHYZYlV+P5S87V5Huhm33YDDVq9dYnPo+qu3bKEf2NaSIwLN+ydRJuB jeWbva07L/SuQ+n9xtj4u6ywLfF75tvyy76NT7RNxpBG9GcKkXUFo5V3yvDThiq6/U/e up5Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1693407870; x=1694012670; h=content-transfer-encoding:in-reply-to:from:references:cc:to:subject :user-agent:mime-version:date:message-id:x-gm-message-state:from:to :cc:subject:date:message-id:reply-to; bh=BY1v90+5NSPW40nepdwawsmQXXDE6gdV3lwX6BIPunA=; b=FVTqPheuDdqBI/Y4DAPCvOgYeDR22M2EZdtM5BUsITWHQhBRAEIJu0ZNGZgcQAd+8D Wb8ePRZKzW9cVzvhXqABODDEiTWecdwfUHlS5tzE7PkHOwhzWG9T1LxtdmC4qyLz0ghZ goFWVXH540pQFV1YTorJ11z6uutnsLIh8Vj42JhHF6pukUdwPqZS5OiDsWp2apqQQa7+ hytxUVNPJpIVoLXZO9NR8a79yRaHWSkgEJQHId9mOSKTElE1ZLTRbYiik6SjrIHLl82T IPeFVKYkavpoMm84yxWwF7a6sXJjcNA+IHs4UJIsPOn+lnFwieqVjp3UI9zSoPfhbcdQ 7lgw== X-Gm-Message-State: AOJu0YwV++pzNfmzi00tANoBxQDQC+0EZcheOf9P5f0A6jIhwYKCfr2P /KpZ8gDhz4NaSh7dFrMxI1I= X-Google-Smtp-Source: AGHT+IHRm7rtzj81ZlIYH0T79lr+GUMNzYCHKFMVKdWz4gEygQ5O/SCsRCq+FFjEb1B0FGxf56amUA== X-Received: by 2002:a05:6a21:9997:b0:14c:c767:a56a with SMTP id ve23-20020a056a21999700b0014cc767a56amr2949112pzb.25.1693407869896; Wed, 30 Aug 2023 08:04:29 -0700 (PDT) Received: from [192.168.255.10] ([101.80.250.8]) by smtp.gmail.com with ESMTPSA id n21-20020aa79055000000b00682a908949bsm10496088pfo.92.2023.08.30.08.04.25 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 30 Aug 2023 08:04:29 -0700 (PDT) Message-ID: <6c691bc5-dbfc-46f9-8c09-9c74c51d8708@gmail.com> Date: Wed, 30 Aug 2023 23:04:21 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH v4 16/29] KVM: x86: Reject memslot MOVE operations if KVMGT is attached To: Sean Christopherson Cc: kvm@vger.kernel.org, intel-gvt-dev@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org, Yan Zhao , Yongwei Ma , Ben Gardon , Zhenyu Wang , Zhi Wang , Paolo Bonzini References: <20230729013535.1070024-1-seanjc@google.com> <20230729013535.1070024-17-seanjc@google.com> From: Like Xu In-Reply-To: <20230729013535.1070024-17-seanjc@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2023/7/29 09:35, Sean Christopherson wrote: > Disallow moving memslots if the VM has external page-track users, i.e. if > KVMGT is being used to expose a virtual GPU to the guest, as KVMGT doesn't > correctly handle moving memory regions. > > Note, this is potential ABI breakage! E.g. userspace could move regions > that aren't shadowed by KVMGT without harming the guest. However, the > only known user of KVMGT is QEMU, and QEMU doesn't move generic memory This change breaks two kvm selftests: - set_memory_region_test; - memslot_perf_test; Please help confirm if the tests/doc needs to be updated, or if the assumption needs to be further clarified. > regions. KVM's own support for moving memory regions was also broken for > multiple years (albeit for an edge case, but arguably moving RAM is > itself an edge case), e.g. see commit edd4fa37baa6 ("KVM: x86: Allocate > new rmap and large page tracking when moving memslot"). > > Reviewed-by: Yan Zhao > Tested-by: Yongwei Ma > Signed-off-by: Sean Christopherson > --- > arch/x86/include/asm/kvm_page_track.h | 3 +++ > arch/x86/kvm/mmu/page_track.c | 5 +++++ > arch/x86/kvm/x86.c | 7 +++++++ > 3 files changed, 15 insertions(+) > > diff --git a/arch/x86/include/asm/kvm_page_track.h b/arch/x86/include/asm/kvm_page_track.h > index 8c4d216e3b2b..f744682648e7 100644 > --- a/arch/x86/include/asm/kvm_page_track.h > +++ b/arch/x86/include/asm/kvm_page_track.h > @@ -75,4 +75,7 @@ kvm_page_track_unregister_notifier(struct kvm *kvm, > void kvm_page_track_write(struct kvm_vcpu *vcpu, gpa_t gpa, const u8 *new, > int bytes); > void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot); > + > +bool kvm_page_track_has_external_user(struct kvm *kvm); > + > #endif > diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c > index 891e5cc52b45..e6de9638e560 100644 > --- a/arch/x86/kvm/mmu/page_track.c > +++ b/arch/x86/kvm/mmu/page_track.c > @@ -303,3 +303,8 @@ void kvm_page_track_flush_slot(struct kvm *kvm, struct kvm_memory_slot *slot) > n->track_flush_slot(kvm, slot, n); > srcu_read_unlock(&head->track_srcu, idx); > } > + > +bool kvm_page_track_has_external_user(struct kvm *kvm) > +{ > + return hlist_empty(&kvm->arch.track_notifier_head.track_notifier_list); > +} > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 059571d5abed..4394bb49051f 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -12606,6 +12606,13 @@ int kvm_arch_prepare_memory_region(struct kvm *kvm, > struct kvm_memory_slot *new, > enum kvm_mr_change change) > { > + /* > + * KVM doesn't support moving memslots when there are external page > + * trackers attached to the VM, i.e. if KVMGT is in use. > + */ > + if (change == KVM_MR_MOVE && kvm_page_track_has_external_user(kvm)) > + return -EINVAL; > + > if (change == KVM_MR_CREATE || change == KVM_MR_MOVE) { > if ((new->base_gfn + new->npages - 1) > kvm_mmu_max_gfn()) > return -EINVAL;