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 6A915C433EF for ; Tue, 22 Mar 2022 18:17:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234501AbiCVSS5 (ORCPT ); Tue, 22 Mar 2022 14:18:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50708 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232080AbiCVSS4 (ORCPT ); Tue, 22 Mar 2022 14:18:56 -0400 Received: from mail-lf1-x136.google.com (mail-lf1-x136.google.com [IPv6:2a00:1450:4864:20::136]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F2BE74DFB for ; Tue, 22 Mar 2022 11:17:27 -0700 (PDT) Received: by mail-lf1-x136.google.com with SMTP id d5so12013387lfj.9 for ; Tue, 22 Mar 2022 11:17:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rjXWwDt+piFjEizKBPLIwkQ3oNcecYs/t2+aRfZKR2Q=; b=e0SsUFEnYUMCyRAkGyLVow0+R4bFdfmash3hSguwzYMReIozuymckocyM5BR/BZLJg F/po3/TlVjopsmXJ41juFAnRzPe45KNaRNkzN0MtvjZ9mBPCEsZrjkO6ujDAemvwda96 rl80jZRhNG2l/NMfwbStZ6I+jDlhs/HdozQzWkjJ80csfkdMlVM4vYTOYFFyjfHkCzzd 9/mg9mIusJIiJ41q4kWg6sKjFXIQgUQguTqgxHiq8PkCHtwIR6pYWShWbrYo5MzF8yp5 bQ749BhKFyRlGHbieptNt6y4VPTEPjdhkDnJ0TPl0KSwq8Nl847v1G4lQzpS2egtD3Nu R/sA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rjXWwDt+piFjEizKBPLIwkQ3oNcecYs/t2+aRfZKR2Q=; b=xayKyqysWAAHwbR3ZEMwRXrxI3c4UPKEp8DuELuFH9GVpQdiPImU09Nv6KHJa6DVOt 52LSk+EI5Fo9U2xrD5ThmKfGSQrGdtgcJ2685+9YzrRaWjkYFZ0k5LYZv3Ve/MHwegNi Lp3ycu09TAdZiZFzpuRo2KpteysVvaUOSSaDSzjWerKVXJIql00xMoR/QU3OIRFcJjH7 a5Qe3folWz9ulZ61qr3ir6acMZiidnYN2z6UBZUod/NE9Wci4V04qoRED+XWmz+UP1xS 68aW80DoJyFlLXYGyeZQFsTypj0nrNbb1JxXGElVpSGFVojcHc7mLk03qxo9MpeHxZAL J+AQ== X-Gm-Message-State: AOAM533u8JEm031geYulG4vMf7eBeD09doLrV6Tu9l+71zIo8xd/ZXus NoMB4gpCUDEYfRIKG1eWL6DUkncB4/z66CywXTAVqg== X-Google-Smtp-Source: ABdhPJxTpXDCogH6wFEbXP5cV7bKAnz+C/vzgCxatvwG3tgn9N4H9nX6rT0RugIgjr0sQJpMf/ysU29QMVGOZ9XlHbA= X-Received: by 2002:ac2:57db:0:b0:44a:23ce:b7f5 with SMTP id k27-20020ac257db000000b0044a23ceb7f5mr9953556lfo.235.1647973045570; Tue, 22 Mar 2022 11:17:25 -0700 (PDT) MIME-Version: 1.0 References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-2-dmatlack@google.com> In-Reply-To: From: David Matlack Date: Tue, 22 Mar 2022 11:16:59 -0700 Message-ID: Subject: Re: [PATCH v2 01/26] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs To: Peter Xu Cc: Paolo Bonzini , Marc Zyngier , Huacai Chen , Aleksandar Markovic , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Sean Christopherson , Andrew Jones , Ben Gardon , "Maciej S. Szmigiero" , "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 Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-mips@vger.kernel.org On Tue, Mar 15, 2022 at 12:40 AM Peter Xu wrote: > > 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? Yes that's correct. I'll include that in the commit message in the next version. > > > > > 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 > 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 mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3980BC433F5 for ; Wed, 23 Mar 2022 09:57:17 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 8A96149F4E; Wed, 23 Mar 2022 05:57:16 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Authentication-Results: mm01.cs.columbia.edu (amavisd-new); dkim=softfail (fail, message has been altered) header.i=@google.com Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id GbqmiXTXf9nl; Wed, 23 Mar 2022 05:57:15 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 79A3B49F58; Wed, 23 Mar 2022 05:57:15 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id F18DE49E37 for ; Tue, 22 Mar 2022 14:17:28 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id rqye5F7PHXlZ for ; Tue, 22 Mar 2022 14:17:27 -0400 (EDT) Received: from mail-lf1-f44.google.com (mail-lf1-f44.google.com [209.85.167.44]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id AC29A411C7 for ; Tue, 22 Mar 2022 14:17:27 -0400 (EDT) Received: by mail-lf1-f44.google.com with SMTP id 5so13021507lfp.1 for ; Tue, 22 Mar 2022 11:17:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=rjXWwDt+piFjEizKBPLIwkQ3oNcecYs/t2+aRfZKR2Q=; b=e0SsUFEnYUMCyRAkGyLVow0+R4bFdfmash3hSguwzYMReIozuymckocyM5BR/BZLJg F/po3/TlVjopsmXJ41juFAnRzPe45KNaRNkzN0MtvjZ9mBPCEsZrjkO6ujDAemvwda96 rl80jZRhNG2l/NMfwbStZ6I+jDlhs/HdozQzWkjJ80csfkdMlVM4vYTOYFFyjfHkCzzd 9/mg9mIusJIiJ41q4kWg6sKjFXIQgUQguTqgxHiq8PkCHtwIR6pYWShWbrYo5MzF8yp5 bQ749BhKFyRlGHbieptNt6y4VPTEPjdhkDnJ0TPl0KSwq8Nl847v1G4lQzpS2egtD3Nu R/sA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=rjXWwDt+piFjEizKBPLIwkQ3oNcecYs/t2+aRfZKR2Q=; b=7609Ix/CaejJxG/hZlFK6z+717Rwe/860XxIm0SKk+GnpEGd+ll2xOCAP2OR6boxIA XoIIwVrmgpkDx0E1+bD1C7ZInvJZGtAN8petqTJloiphAmHGTwtBytMHX80x6ktZhvDD NjNcuEDGqdHxgVbxZbv9/cBcSs0HJmhMJSqX6iuuzcuzgUtxP0VgZ5x6QhV4OfF3o79M W3F5KJPwcVAfVcZbRKTKrOppt0d7sfHfIgG32YF76fhQrSURIdjBaUsf7rCZoT8BCdxr ik2J9208eIAYeIpWI0isTO5L0GoysFltVxUNA5ooR3g9824jwLjbDw0DefW/2KtqJe2L bvCw== X-Gm-Message-State: AOAM531SNL7YYF4+QkDV5ezv2dy/14ocAdMLOjt/pdv3LcFvezpaVW0g 7EBlwaUvSx1H++rEfxjEOuSQgcyvqGGIuL/kNd18Dw== X-Google-Smtp-Source: ABdhPJxTpXDCogH6wFEbXP5cV7bKAnz+C/vzgCxatvwG3tgn9N4H9nX6rT0RugIgjr0sQJpMf/ysU29QMVGOZ9XlHbA= X-Received: by 2002:ac2:57db:0:b0:44a:23ce:b7f5 with SMTP id k27-20020ac257db000000b0044a23ceb7f5mr9953556lfo.235.1647973045570; Tue, 22 Mar 2022 11:17:25 -0700 (PDT) MIME-Version: 1.0 References: <20220311002528.2230172-1-dmatlack@google.com> <20220311002528.2230172-2-dmatlack@google.com> In-Reply-To: From: David Matlack Date: Tue, 22 Mar 2022 11:16:59 -0700 Message-ID: Subject: Re: [PATCH v2 01/26] KVM: x86/mmu: Optimize MMU page cache lookup for all direct SPs To: Peter Xu X-Mailman-Approved-At: Wed, 23 Mar 2022 05:57:13 -0400 Cc: Marc Zyngier , Albert Ou , "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" , Huacai Chen , "open list:KERNEL VIRTUAL MACHINE FOR MIPS \(KVM/mips\)" , Aleksandar Markovic , Palmer Dabbelt , "open list:KERNEL VIRTUAL MACHINE FOR RISC-V \(KVM/riscv\)" , Paul Walmsley , Ben Gardon , Paolo Bonzini , "Maciej S. Szmigiero" , "moderated list:KERNEL VIRTUAL MACHINE FOR ARM64 \(KVM/arm64\)" , Peter Feiner X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Tue, Mar 15, 2022 at 12:40 AM Peter Xu wrote: > > 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? Yes that's correct. I'll include that in the commit message in the next version. > > > > > 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 > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm