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 DDA5EC433FE for ; Fri, 25 Mar 2022 20:22:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232181AbiCYUYT (ORCPT ); Fri, 25 Mar 2022 16:24:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53008 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232152AbiCYUYR (ORCPT ); Fri, 25 Mar 2022 16:24:17 -0400 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 263DD66CB9 for ; Fri, 25 Mar 2022 13:22:42 -0700 (PDT) Received: by mail-pg1-x531.google.com with SMTP id b130so5877329pga.13 for ; Fri, 25 Mar 2022 13:22:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=cSxVhb71z+Ee83vpaUYArlMABtaVLB8rzZSlwyaMw5Y=; b=KOZWScWPx5LRthiYDgPnYHcm3/Fe4PAO4T9J+5Ol7Lm1rlbLvP/B0+KyVQD0rTaF4p wv1DwFSBGhrVba45FhNgBzQR9lUWbJdjYBQFxGsFehV0gt2yQaxXxse/HodR5w2iwy3A HXijCz6A3szsLmM4fRii8V1p21M+LerdSCjeJ6TLY6BTSHwXIF/eM81Hm54tc57e+vc7 RYZquCLfJGxGsk2HVd54V83PUA0kNwSwY8lXY4Yri9PDAMlQAjHnFHHh+sKoNVrjLLvm bWUBTDaW95QQFMlT8iHYvpphTo4tRtUP2EFSiLdeeEiIJdX0sROyhBDyPYgj7qbhA+nP Zu7Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=cSxVhb71z+Ee83vpaUYArlMABtaVLB8rzZSlwyaMw5Y=; b=lmYM13ExuLRg+2RNQaSdmFADszIThteNXiRKLjoyYiTOhCIJ+bzBHi44VH7/Be1rO/ +JxlmgTypoeBraLp80HJoB7a9JL0KUAG1kBkXXC7We+Ymd9XiLb1ylRXfkyWUy0z3r06 ywmDuUOELLS12LSb7TPLOSIm4Zt5pRM1dY93NrNBfstixUKQTNz79wbnqo4M5V/crLUv UVH0LoA8fpW0mBH85VueA2FfDK9J7sJcKxBfYw2Mv0GPVjqgU5fU+DKv8+cVLIdRNDfC zYkwLyUQu4LBCcEV0C0LLBjumEcGB55Drz9D6WqqxnG1wGk7Q8EqXeG1b6vBqKwP2ANa 2wUQ== X-Gm-Message-State: AOAM532lojIIFZp82jSIIdwHF7R1Sg1ZvnmsNb/UWBCXiQNtztCNYxET WHm3Z3wJ57beTgIltFwOfZbrLw== X-Google-Smtp-Source: ABdhPJzsYhW4Lj1IXnf4NIGQcY6MlWE3y8J/vp4aaF0mlpwG6vx59jXFeTzBbZah9AjymJqdXjJkyg== X-Received: by 2002:a63:4859:0:b0:381:ede3:9af0 with SMTP id x25-20020a634859000000b00381ede39af0mr1013244pgk.87.1648239761482; Fri, 25 Mar 2022 13:22:41 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id gb5-20020a17090b060500b001c6d46f7e75sm13815829pjb.30.2022.03.25.13.22.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 25 Mar 2022 13:22:40 -0700 (PDT) Date: Fri, 25 Mar 2022 20:22:37 +0000 From: Sean Christopherson To: Paolo Bonzini Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, Vitaly Kuznetsov , Sean Christopherson Subject: Re: [FYI PATCH] Revert "KVM: x86/mmu: Zap only TDP MMU leafs in kvm_zap_gfn_range()" Message-ID: References: <20220318164833.2745138-1-pbonzini@redhat.com> <78e3f054-829e-b00d-6c65-9ae622f301df@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <78e3f054-829e-b00d-6c65-9ae622f301df@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 25, 2022, Paolo Bonzini wrote: > On 3/25/22 00:57, Sean Christopherson wrote: > > Can I have 1-2 weeks to try and root cause and fix the underlying issue before > > sending reverts to Linus? I really don't want to paper over a TLB flushing bug > > or an off-by-one bug, and I really, really don't want to end up with another > > scenario where KVM zaps everything just because. > > Well, too late... I didn't want to send a pull request that was broken, Ah, I didn't see that it was in the initial pull request, thought it was only in kvm/next. I'll send a full patch. > Mingwei provided a convincing reason for the breakage. No, the side effects are completely benign, and arguably desirable. The issue is that KVM loses a pending TLB flush if there are multiple roots.