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 A7D73C433F5 for ; Fri, 8 Apr 2022 10:11:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229586AbiDHKNK (ORCPT ); Fri, 8 Apr 2022 06:13:10 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234498AbiDHKMl (ORCPT ); Fri, 8 Apr 2022 06:12:41 -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 BA7339F3A1 for ; Fri, 8 Apr 2022 03:10:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1649412637; 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=dDv/rk0p/ym3Otaap0CgRvB/aOstceiT80X2oN268IM=; b=IAoQCqkIzlu+4Hk7fyAfvYV5vd07ulJ6K3CdCRJllErxiRIKYejYIKptisVgshDP9ih2Rd NzGeYq+1PBlNzHphpti8OXkJ0M0iXKLzDoZg2PgZiwTVHqskJVRz+XIEsjQLpfh2Ii6vYK jbmsbdpM8fl3/ndnDq+5Ves0/4lH0w0= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-208-EyQbJNhMMbCV_gLwVWvWUg-1; Fri, 08 Apr 2022 06:10:36 -0400 X-MC-Unique: EyQbJNhMMbCV_gLwVWvWUg-1 Received: by mail-wm1-f71.google.com with SMTP id i6-20020a05600c354600b0038be262d9d9so5747589wmq.8 for ; Fri, 08 Apr 2022 03:10:36 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=dDv/rk0p/ym3Otaap0CgRvB/aOstceiT80X2oN268IM=; b=CPNVYDN2tUbgcqjm0rfNg3AoSbTNnwm/qm7Lmq1d3tG9vWjP54xFiHAVos9onnZt2O yRhN+DwDFs6D9+sOOtCqQnUeBgILyipWotKvb8ZRYkQ98gCUX+zxXWfihrVOLgoGGPSK f+1473Xr2lmrQoLHOG1hVw3A+vGsz15FI58fdyALZD76IQZVBKNtC4ksS/v3d2KSOyQI tUcYnWS87q/SdEm+IpM/yPJOsFurE5pVhiu3nONDQFmtbS3Oi9fGn4jMKeWcgQ+CaRu5 YrzO/QIpG1S9lyVBUwk70wLkYGJD85nQx9RUGkIyo/BQSXbyGVmWHn3mg6eabNvcQDYE xYtw== X-Gm-Message-State: AOAM533kYkJ4XYd7b1XBF2uqQr3sNV4+muhOFf6wrG/vgIEXPiPdOEJY xUdGyr/ebeT4P27ugqbMbrqgB68qRc3Cxj4N/chTAzxXKkpymUEcCuTbEMTBM85/JAaF+i5FDbp w9stVwfRmVe6qyiXM3Q4ZhvrG X-Received: by 2002:a5d:4712:0:b0:206:120d:b038 with SMTP id y18-20020a5d4712000000b00206120db038mr14696767wrq.542.1649412635424; Fri, 08 Apr 2022 03:10:35 -0700 (PDT) X-Google-Smtp-Source: ABdhPJz1beWVQuoGGl5w6Zz3Zazu8hP0ijuNjw/pQk7dZcuH0wdWMvMcyHhbw6FqT4wuqPomqK5XFw== X-Received: by 2002:a5d:4712:0:b0:206:120d:b038 with SMTP id y18-20020a5d4712000000b00206120db038mr14696747wrq.542.1649412635207; Fri, 08 Apr 2022 03:10:35 -0700 (PDT) Received: from [10.32.181.87] (nat-pool-mxp-t.redhat.com. [149.6.153.186]) by smtp.googlemail.com with ESMTPSA id n65-20020a1c2744000000b003862bfb509bsm9776282wmn.46.2022.04.08.03.10.33 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 08 Apr 2022 03:10:34 -0700 (PDT) Message-ID: Date: Fri, 8 Apr 2022 12:10:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH] KVM: x86/mmu: remove unnecessary kvm_shadow_root_allocated() check Content-Language: en-US To: luofei , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org Cc: seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, joro@8bytes.org, hpa@zytor.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220407014016.1266469-1-luofei@unicloud.com> From: Paolo Bonzini In-Reply-To: <20220407014016.1266469-1-luofei@unicloud.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 4/7/22 03:40, luofei wrote: > When we reach here, the return value of kvm_shadow_root_allocated() > has already been checked to false under kvm->slots_arch_lock. > So remove the unnecessary recheck. It's a little less clear t check !is_tdp_mmu_enabled(). That said, this is only done once, so perhaps it's better/easier to just remove the if completely. Paolo > Signed-off-by: luofei > --- > arch/x86/kvm/mmu/mmu.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > index 8f19ea752704..1978ee527298 100644 > --- a/arch/x86/kvm/mmu/mmu.c > +++ b/arch/x86/kvm/mmu/mmu.c > @@ -3394,7 +3394,7 @@ static int mmu_first_shadow_root_alloc(struct kvm *kvm) > * Check if anything actually needs to be allocated, e.g. all metadata > * will be allocated upfront if TDP is disabled. > */ > - if (kvm_memslots_have_rmaps(kvm) && > + if (!is_tdp_mmu_enabled(kvm) && > kvm_page_track_write_tracking_enabled(kvm)) > goto out_success; >