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 41C2FC433F5 for ; Tue, 15 Mar 2022 07:40:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345570AbiCOHlm (ORCPT ); Tue, 15 Mar 2022 03:41:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60612 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1345607AbiCOHle (ORCPT ); Tue, 15 Mar 2022 03:41:34 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 201BE4B867 for ; Tue, 15 Mar 2022 00:40:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1647330018; 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: in-reply-to:in-reply-to:references:references; bh=uq0Z2NOXqlkVrEm1qJusGexqNZk1tmem0xILqLvczWc=; b=flkWWW1HKdXs3++8E25mr0vdkz/5aivM/5EJy7jojqxuUmGmswgh9Unk7DXZH7m4kk4OEO ezW7oP9uZg8y+0YSrUQ5K7FED4BW8hHf43MY0MD9+teq/KdyI88TCaQ3HU3oAkvrOYRBXX f1z+jIFkD1Bk3/IYxFMNTckuLl7CQ10= Received: from mail-pf1-f197.google.com (mail-pf1-f197.google.com [209.85.210.197]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-648-snilo69QO62Dk37ygoC15A-1; Tue, 15 Mar 2022 03:40:15 -0400 X-MC-Unique: snilo69QO62Dk37ygoC15A-1 Received: by mail-pf1-f197.google.com with SMTP id y7-20020a626407000000b004f6d39f1b0fso11254295pfb.5 for ; Tue, 15 Mar 2022 00:40:15 -0700 (PDT) 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=uq0Z2NOXqlkVrEm1qJusGexqNZk1tmem0xILqLvczWc=; b=Hv5ABIKi8tKJgSg3ihi516Fuv2MZ/aNxY7pcp1/8qEdqECyoImezXdS0Xq5E1UMGvy yaFrT9I54HlMhK+v69BvIxi9VFo/nF5CwewqCvVzrB4LX+T7xGchvRzGMpN10PYKzoQ8 GzRg2+Z2gjzlZz7udI78dsFOxevR2JGS9x4YwSuRVSXTpHgApFruN3WynkDCxVZOoEtg FAHo5/ca+dCWKJ7VToR8NV2w3IBtOkj5KDDFMT41X37Wpumj7qsE/bqCX3ytsTN0prNc gomMDxupE5U1gxONU7svevNBxc+EiNNnQ5iKjqlyjN9BdRiSqCb+41VnISioCWJ0XC8U vCJg== X-Gm-Message-State: AOAM5316PCnraE0t2fVg2lPJuRAY3hUfRFoiceIpXhrCKjeTUctIL6lM 9tYoOGWA8Sss0pYp7j1jLRq7aa/o/akHMI5B4GqKj6ars7tVNxCpANc8JhlalNejvKB3Yz9DWEj mS1fzvSK5QWWOt5IIYp1GFw== X-Received: by 2002:a63:4543:0:b0:374:87b6:c9f5 with SMTP id u3-20020a634543000000b0037487b6c9f5mr23348156pgk.302.1647330014626; Tue, 15 Mar 2022 00:40:14 -0700 (PDT) X-Google-Smtp-Source: ABdhPJztMHMNYKIpNAuJc8FteBiELgu/J7bC35KETwQh5TE/MrV9Kwi39pAoHxQ4fUsa/R32a5KHkg== X-Received: by 2002:a63:4543:0:b0:374:87b6:c9f5 with SMTP id u3-20020a634543000000b0037487b6c9f5mr23348131pgk.302.1647330014348; Tue, 15 Mar 2022 00:40:14 -0700 (PDT) Received: from xz-m1.local ([191.101.132.43]) by smtp.gmail.com with ESMTPSA id c7-20020aa78e07000000b004f6e4d8ccc8sm22380450pfr.163.2022.03.15.00.40.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Mar 2022 00:40:14 -0700 (PDT) Date: Tue, 15 Mar 2022 15:40:05 +0800 From: Peter Xu To: David Matlack Cc: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Andrew Jones , Ben Gardon , maciej.szmigiero@oracle.com, "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)" , "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" , "open list:KERNEL VIRTUAL MACHINE FOR MIPS (KVM/mips)" , "open list:KERNEL VIRTUAL MACHINE FOR RISC-V (KVM/riscv)" , Peter Feiner Subject: Re: [PATCH v2 01/26] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs Message-ID: References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-2-dmatlack@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20220311002528.2230172-2-dmatlack@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Fri, Mar 11, 2022 at 12:25:03AM +0000, David Matlack wrote: > Commit fb58a9c345f6 ("KVM: x86/mmu: Optimize MMU page cache lookup for > fully direct MMUs") skipped the unsync checks and write flood clearing > for full direct MMUs. We can extend this further and skip the checks for > all direct shadow pages. Direct shadow pages are never marked unsynced > or have a non-zero write-flooding count. Nit: IMHO it's better to spell out the exact functional change, IIUC those are the direct mapped SPs where guest uses huge pages but host uses only small pages for the shadowing? > > Checking sp->role.direct alos generates better code than checking > direct_map because, due to register pressure, direct_map has to get > shoved onto the stack and then pulled back off. > > No functional change intended. > > Reviewed-by: Sean Christopherson > Signed-off-by: David Matlack Reviewed-by: Peter Xu -- Peter Xu