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 1534BC433FE for ; Thu, 17 Nov 2022 20:10:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234998AbiKQUKM (ORCPT ); Thu, 17 Nov 2022 15:10:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53282 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232330AbiKQUKI (ORCPT ); Thu, 17 Nov 2022 15:10:08 -0500 Received: from mail-pj1-x1032.google.com (mail-pj1-x1032.google.com [IPv6:2607:f8b0:4864:20::1032]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A7E97EBD4; Thu, 17 Nov 2022 12:10:08 -0800 (PST) Received: by mail-pj1-x1032.google.com with SMTP id k5so2614872pjo.5; Thu, 17 Nov 2022 12:10:08 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=I6j1W3Ji+fdVPC6gf2n+swdKOz5mGcn5yydkS5FTGpA=; b=etd/G7iaKExY97a+7RFVEc/mtw7VNG9n+VHfEyE9IJatKO7FWet1pvhGQJaWzV91h9 ZuCE+uPGyhFP5wP335ZGwfkf4ddZtUeTbalZZo6y9gg+VBjhfBHAKuN3MMO2U/A49Cnj ZnTIeHk2e65GQUxPOa1XGBlbWhbiwvNM/Q9LwNQ8MQ8Ktk2YzzgyHV2FBLQpZ9g7VFyU xSJnmW7s68ycW8hiKd14WZ5l37Jiiun6VKthVwDyFBWavZFcH/92ropyZaRgqNiSK1If SZgPkEDMKrxZCVxKSaVrNlJnp5zrNhxbIQQWTa9q1czULbL2xtqEX2Umi/BhVi4MFSSw Spnw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=I6j1W3Ji+fdVPC6gf2n+swdKOz5mGcn5yydkS5FTGpA=; b=32hcePc+9tdOo6fB/NSP/D98nBmpacAW7YkDBF0N1jMIS6j0vEddq5d5LsNpOi3Npm kfOnOOWVwKav+Wgqg7E5k1KOBhc6lg2NzD2cKAZ4PJnfnaecmX/rSBam1yN9YD/V/J1y WHtZkSKyNeomxMGKiW7gpuj1uza2rRKSyfMMNLjj86KCQ/A7CQ7koyJXIGP5LwPYqrep 5BQf8KmyVz55ikQNN4Ae/CCOx9yL7M12/MYGwwQhXLMc7OsSOiwN16JXDc0DJPRkcYTC l+oMI1u7CJ4/ZtqqGRPZ+qfBZJtEfZKos7ZV76Zr5G+MvfK74hJN2cr+dMyNLPqbUmt1 HI7g== X-Gm-Message-State: ANoB5pm3mDOHyEHBSRovRxR+ar8lSdVtyatT+SS162x8epibjHGFgDOz t/LWYv+CPfjLUJMyoM7SaCQ= X-Google-Smtp-Source: AA0mqf5O1RehkPJLM2QkkzuuSpXswc1sc9uOH8KL8Ye5kzPbbbn0vg6BxXBK3syXAQmhi7n/KLV/3w== X-Received: by 2002:a17:902:f111:b0:186:ee56:4a1e with SMTP id e17-20020a170902f11100b00186ee564a1emr4208717plb.167.1668715806451; Thu, 17 Nov 2022 12:10:06 -0800 (PST) Received: from localhost ([192.55.54.55]) by smtp.gmail.com with ESMTPSA id r14-20020a65498e000000b00476f2b11c07sm1450318pgs.5.2022.11.17.12.10.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Nov 2022 12:10:05 -0800 (PST) Date: Thu, 17 Nov 2022 12:10:04 -0800 From: Isaku Yamahata To: Binbin Wu Cc: isaku.yamahata@intel.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, isaku.yamahata@gmail.com, Paolo Bonzini , erdemaktas@google.com, Sean Christopherson , Sagi Shahar , David Matlack , Chao Gao Subject: Re: [PATCH v10 071/108] KVM: x86: Allow to update cached values in kvm_user_return_msrs w/o wrmsr Message-ID: <20221117201004.GA2751024@ls.amr.corp.intel.com> References: <238ab2d9a9d2ea71ecacb25203b91abbaf6fbcb4.1667110240.git.isaku.yamahata@intel.com> <8584a9c7-0ec1-db36-bb32-d508a091ea09@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <8584a9c7-0ec1-db36-bb32-d508a091ea09@linux.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 14, 2022 at 03:36:27PM +0800, Binbin Wu wrote: > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > index 65541bfebb37..4d4b71c4cdb1 100644 > > --- a/arch/x86/kvm/x86.c > > +++ b/arch/x86/kvm/x86.c > > @@ -440,6 +440,15 @@ void kvm_user_return_msr_init_cpu(void) > > } > > EXPORT_SYMBOL_GPL(kvm_user_return_msr_init_cpu); > > +static void kvm_user_return_register_notifier(struct kvm_user_return_msrs *msrs) > > +{ > > + if (!msrs->registered) { > > + msrs->urn.on_user_return = kvm_on_user_return; > > + user_return_notifier_register(&msrs->urn); > > + msrs->registered = true; > > + } > > +} > > + > > int kvm_set_user_return_msr(unsigned slot, u64 value, u64 mask) > > { > > struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs); > > @@ -455,15 +464,22 @@ int kvm_set_user_return_msr(unsigned slot, u64 value, u64 mask) > > return 1; > > msrs->values[slot].curr = value; > > - if (!msrs->registered) { > > - msrs->urn.on_user_return = kvm_on_user_return; > > - user_return_notifier_register(&msrs->urn); > > - msrs->registered = true; > > - } > > + kvm_user_return_register_notifier(msrs); > > return 0; > > } > > EXPORT_SYMBOL_GPL(kvm_set_user_return_msr); > > +/* Update the cache, "curr", and register the notifier */ > > +void kvm_user_return_update_cache(unsigned int slot, u64 value) > > +{ > > + struct kvm_user_return_msrs *msrs = this_cpu_ptr(user_return_msrs); > > + > > + WARN_ON_ONCE(!msrs->initialized); > > + msrs->values[slot].curr = value; > > If the value is the same as the cached one, can it just skip notifier > registration? We know tha the the user of the function (in the next patch) passes the different value, the initial reset value in the return of TDH.VP.ENTER. So such check isn't added. -- Isaku Yamahata