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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 D2B2EC433EF for ; Mon, 13 Sep 2021 09:57:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B484160F5D for ; Mon, 13 Sep 2021 09:57:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238742AbhIMJ6c (ORCPT ); Mon, 13 Sep 2021 05:58:32 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:58551 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238043AbhIMJ6b (ORCPT ); Mon, 13 Sep 2021 05:58:31 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1631527035; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=siVDFr3S9ONYfda+VIgXBw6wFuMXnGso09DgHdeWDFw=; b=Pul+uPUmRBDHxBcQdbFjiTmpc8XFDYxLW1SCxQFCkGEINBkwMgx8WH1EzdV/nvo+TSDTIO GqZ1YaTcn4SWMppLhZ+I+BPg6sMne04I9w3v3m82CkzEKqWmCoBlIo5jlp7iTxF4hP93Le E6R8evdUHziIp0XAT4an41cIPJ7164I= 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-227--9ytZSgmPYqLHdjCP02Xsg-1; Mon, 13 Sep 2021 05:57:14 -0400 X-MC-Unique: -9ytZSgmPYqLHdjCP02Xsg-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AC69D835DE3; Mon, 13 Sep 2021 09:57:12 +0000 (UTC) Received: from starship (unknown [10.35.206.50]) by smtp.corp.redhat.com (Postfix) with ESMTP id 785D95C25A; Mon, 13 Sep 2021 09:57:04 +0000 (UTC) Message-ID: <9b70aeb7b6829f3d20da05f888f58eaa1c9abee6.camel@redhat.com> Subject: Re: [PATCH 1/7] KVM: X86: Fix missed remote tlb flush in rmap_write_protect() From: Maxim Levitsky To: Lai Jiangshan , linux-kernel@vger.kernel.org Cc: Paolo Bonzini , Lai Jiangshan , Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Marcelo Tosatti , Avi Kivity , kvm@vger.kernel.org Date: Mon, 13 Sep 2021 12:57:03 +0300 In-Reply-To: <20210824075524.3354-2-jiangshanlai@gmail.com> References: <20210824075524.3354-1-jiangshanlai@gmail.com> <20210824075524.3354-2-jiangshanlai@gmail.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-08-24 at 15:55 +0800, Lai Jiangshan wrote: > From: Lai Jiangshan > > When kvm->tlbs_dirty > 0, some rmaps might have been deleted > without flushing tlb remotely after kvm_sync_page(). If @gfn > was writable before and it's rmaps was deleted in kvm_sync_page(), > we need to flush tlb too even if __rmap_write_protect() doesn't > request it. > > Fixes: 4731d4c7a077 ("KVM: MMU: out of sync shadow core") > Signed-off-by: Lai Jiangshan > --- > arch/x86/kvm/mmu/mmu.c | 16 ++++++++++++++++ > 1 file changed, 16 insertions(+) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 4853c033e6ce..313918df1a10 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -1420,6 +1420,14 @@ bool kvm_mmu_slot_gfn_write_protect(struct kvm *kvm, > rmap_head = gfn_to_rmap(gfn, i, slot); > write_protected |= __rmap_write_protect(kvm, rmap_head, true); > } > + /* > + * When kvm->tlbs_dirty > 0, some rmaps might have been deleted > + * without flushing tlb remotely after kvm_sync_page(). If @gfn > + * was writable before and it's rmaps was deleted in kvm_sync_page(), > + * we need to flush tlb too. > + */ > + if (min_level == PG_LEVEL_4K && kvm->tlbs_dirty) > + write_protected = true; This is a bit misleading, as the gfn is not write protected in this case, but we just want tlb flush. Maybe add a new output paramter to the function, telling if we want a tlb flush? > } > > if (is_tdp_mmu_enabled(kvm)) > @@ -5733,6 +5741,14 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, > flush = slot_handle_level(kvm, memslot, slot_rmap_write_protect, > start_level, KVM_MAX_HUGEPAGE_LEVEL, > false); > + /* > + * When kvm->tlbs_dirty > 0, some rmaps might have been deleted > + * without flushing tlb remotely after kvm_sync_page(). If @gfn > + * was writable before and it's rmaps was deleted in kvm_sync_page(), > + * we need to flush tlb too. > + */ > + if (start_level == PG_LEVEL_4K && kvm->tlbs_dirty) > + flush = true; > write_unlock(&kvm->mmu_lock); > } > Best regards, Maxim Levitsky