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([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.gmail.com with ESMTPSA id n186sm7166424wme.31.2021.10.01.02.17.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 Oct 2021 02:17:41 -0700 (PDT) Message-ID: <48151d08-ee29-2b98-b6e1-f3c8a1ff26bc@redhat.com> Date: Fri, 1 Oct 2021 11:17:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace Content-Language: en-US To: Marcelo Tosatti , Oliver Upton Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Andrew Jones , Will Deacon , Catalin Marinas References: <20210916181538.968978-1-oupton@google.com> <20210916181538.968978-8-oupton@google.com> <20210930191416.GA19068@fuller.cnet> From: Paolo Bonzini In-Reply-To: <20210930191416.GA19068@fuller.cnet> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 30/09/21 21:14, Marcelo Tosatti wrote: >> + new_off_n = t_0 + off_n + (k_1 - k_0) * freq - t_1 > Hi Oliver, > > This won't advance the TSC values themselves, right? Why not? It affects the TSC offset in the vmcs, so the TSC in the VM is advanced too. Paolo > This (advancing the TSC values by the realtime elapsed time) would be > awesome because TSC clock_gettime() vdso is faster, and some > applications prefer to just read from TSC directly. > See "x86: kvmguest: use TSC clocksource if invariant TSC is exposed". > > The advancement with this patchset only applies to kvmclock. > 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 59C75C433EF for ; Fri, 1 Oct 2021 09:17:49 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id CC18A61A81 for ; Fri, 1 Oct 2021 09:17:48 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org CC18A61A81 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 1CF834B0A3; Fri, 1 Oct 2021 05:17:48 -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=@redhat.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 bott2wJXN2O8; Fri, 1 Oct 2021 05:17:47 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 2BA714B0B4; Fri, 1 Oct 2021 05:17:47 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id E9B244B0A3 for ; Fri, 1 Oct 2021 05:17:45 -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 J0BL0q8trLku for ; Fri, 1 Oct 2021 05:17:44 -0400 (EDT) Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by mm01.cs.columbia.edu (Postfix) with ESMTP id DB6BF49DE7 for ; Fri, 1 Oct 2021 05:17:44 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633079864; 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=DGyCDTmKE3Puz9hbd1Bqa93m33TW7tkrO1GY0BEiFrw=; b=G8Jl4WIKybM+gbcJax7zMZCw3ZEU2m9u551hCKS16JVEO7DJOd0IsOiVp9aJMUdjrrHgJT MszqJ/XlzOn3w9bdqN+qvjwLLnJ8WNDgr/+1lRE25I4ENeneZAmE1JgDKJv69vRf4NkY0I 2HIAmdhQZAawn6qQcfiyhuxGF8DTAI0= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-232-jmgli2xbOwyiX08n5KR03w-1; Fri, 01 Oct 2021 05:17:43 -0400 X-MC-Unique: jmgli2xbOwyiX08n5KR03w-1 Received: by mail-wr1-f71.google.com with SMTP id j15-20020a5d564f000000b00160698bf7e9so2601067wrw.13 for ; Fri, 01 Oct 2021 02:17:43 -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=DGyCDTmKE3Puz9hbd1Bqa93m33TW7tkrO1GY0BEiFrw=; b=RO5xAA99vDqC7GHqyxSkvUWxqHUr8si8d2/GBsKFiN8stPW9ztB6ELFg0tYx1HBX5O UnzWW+PbUo+XbXBQZmeLlqfFaWK7wjjgcDbJ0KYNwRe92AXcB7NRobMThi0Rdlw4UjzG 2gW1iQm0LnjKFou5Y4TzqOnawTA5DEWd4sMDnIpTtBZqQrjlWHnOhepFqJm5K7+fWUS4 ZonNSI8R9cHaDoBfDXpef+sHi8kMGYVBkHz6wFWcdnyYppRwRP7wYHjbGd2VYN4UgSYB tigNcNNsbF9hjLKu7Ub7DvOPo5Iu/vxI9LUJo7lrDfB/1LJuFEoB7ghMMQdaUwPrpWzg glDA== X-Gm-Message-State: AOAM5310qVN2C7+F9YTgY9RW2RFzCAJdAqj73MGUoUp8gVR5ENamT5jC g74t0mczNs0bohltpBhYbyyOInNKsGMwWV832e43cIYYBYFN4N7Cmpv+9uRVYNCzkoocmxfWjZj vZarQBbrzH7t5F/Ce/GsJgTbk X-Received: by 2002:a5d:50cf:: with SMTP id f15mr11412196wrt.237.1633079862450; Fri, 01 Oct 2021 02:17:42 -0700 (PDT) X-Google-Smtp-Source: ABdhPJykQN7F6N2QxuVMMTUM6KC2ZEoYFdxkECApzvn9zqqq6yIts+XecYdFr57VC3hfX4SQo9I9wA== X-Received: by 2002:a5d:50cf:: with SMTP id f15mr11412163wrt.237.1633079862215; Fri, 01 Oct 2021 02:17:42 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:63a7:c72e:ea0e:6045? ([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.gmail.com with ESMTPSA id n186sm7166424wme.31.2021.10.01.02.17.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 Oct 2021 02:17:41 -0700 (PDT) Message-ID: <48151d08-ee29-2b98-b6e1-f3c8a1ff26bc@redhat.com> Date: Fri, 1 Oct 2021 11:17:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace To: Marcelo Tosatti , Oliver Upton References: <20210916181538.968978-1-oupton@google.com> <20210916181538.968978-8-oupton@google.com> <20210930191416.GA19068@fuller.cnet> From: Paolo Bonzini In-Reply-To: <20210930191416.GA19068@fuller.cnet> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Cc: Catalin Marinas , kvm@vger.kernel.org, Will Deacon , Peter Shier , Marc Zyngier , David Matlack , kvmarm@lists.cs.columbia.edu, linux-arm-kernel@lists.infradead.org, Jim Mattson 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On 30/09/21 21:14, Marcelo Tosatti wrote: >> + new_off_n = t_0 + off_n + (k_1 - k_0) * freq - t_1 > Hi Oliver, > > This won't advance the TSC values themselves, right? Why not? It affects the TSC offset in the vmcs, so the TSC in the VM is advanced too. Paolo > This (advancing the TSC values by the realtime elapsed time) would be > awesome because TSC clock_gettime() vdso is faster, and some > applications prefer to just read from TSC directly. > See "x86: kvmguest: use TSC clocksource if invariant TSC is exposed". > > The advancement with this patchset only applies to kvmclock. > _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 685BFC433EF for ; Fri, 1 Oct 2021 09:19:38 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 32E6A61A05 for ; Fri, 1 Oct 2021 09:19:38 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 32E6A61A05 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To:Subject: MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=WyKx6I0u9YtZJWsz6LXX1dOP+933Ktr+jHiBXRIYSCU=; b=ImTXXXx5MblK87 CnZn8lKyQN2oZSY912yUvNK8rn5v2tT8RCZ3ilIfEMY00o7HeWXpNDYsodJZYVMp5n5nuKvntqqNT Fd3F8kZVlqW7hiUh8IC2s3rP+RGmg9mDGZcEQ/5th6xo3F8LVXB7XgmmZjlyLaATDRsUFIwfH9wJl JefxX1m7e4lYr7h+DabHIb+LZR5oy4oaehzzTqOSY1pqVzet/2nAzwevWpsiQ6KgcjMgUWjxB+ZMb a6rvFcUFK8S6BEyGZsloxev1U2iZhAhrwHK8/R/K4qJRG+v5iUu0boeKGVFuVFq9D+zVmT0ZBrqgZ yWrQxcUSNm0KsDDYbcoA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1mWEfz-00HBh3-2p; Fri, 01 Oct 2021 09:17:55 +0000 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1mWEfs-00HBdy-T3 for linux-arm-kernel@lists.infradead.org; Fri, 01 Oct 2021 09:17:50 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1633079866; 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=DGyCDTmKE3Puz9hbd1Bqa93m33TW7tkrO1GY0BEiFrw=; b=XrhApoSEwNb0GpHTpv3slfHJHNC52Ohh7yOVMpQUtUiwGpYyDybVwtTkF0fpyfLVZ0/Gz1 zB9ReDAVuaTHkRS4eHqjJdXFyTZhON6yFqBfNxxj3tZgpAAEYVNnAWqqjs0ZgPeir4oja8 y9lzKqLM/MgpSeXX8HNFBUZ+PQudgV0= Received: from mail-wm1-f70.google.com (mail-wm1-f70.google.com [209.85.128.70]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-126-DY7iKwyvP62cstOng7G2zQ-1; Fri, 01 Oct 2021 05:17:43 -0400 X-MC-Unique: DY7iKwyvP62cstOng7G2zQ-1 Received: by mail-wm1-f70.google.com with SMTP id m9-20020a05600c4f4900b003057c761567so5711331wmq.1 for ; Fri, 01 Oct 2021 02:17:43 -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=DGyCDTmKE3Puz9hbd1Bqa93m33TW7tkrO1GY0BEiFrw=; b=hz97ylSdzq7AtFiKBxnKU/exwN+NQxa72gUTk0O1gfnz0xElU/+Wq4ADVr2ZkzTlAB uiSmG3MtpDqCdf/ibdN8CWu9GHOOwqOWKYBvqZtBMmc7wWBftJ8WBbqkIdpS02RZozvk Xm25c3NfaMasJsKiCcPzEkBwMqpQH6wEbD53v+wY2RMURjhOr6oqbTrcgfAm9foZT4np Y02lokfOqcEDNlJwjsg4PN8WPyqq143YZlq/G2r5mkh4hGRzvWGVkrquPFqrRLej0K90 uYQ8aEserL3LPrOTQSlPOSIeCbR+KuGJyBez6MLQ0qhtybAumIdL2vHlhiS12cECJP6k 12xw== X-Gm-Message-State: AOAM533rUb+O5DHtIPxEuutN9BIhmhBMvDiGyanr8yotl0bFysTXc2j+ fzBFI+oL1JkWdOAQWtuMp6ZbTf9EIvVse4jgTpCSKPqSgue/Amd3AHAAiSGSkL+ortnxfQ+SV/C Y9frW+sQys/8TNn1mrXZZ6vk9pJVCgI2H2O0= X-Received: by 2002:a5d:50cf:: with SMTP id f15mr11412192wrt.237.1633079862450; Fri, 01 Oct 2021 02:17:42 -0700 (PDT) X-Google-Smtp-Source: ABdhPJykQN7F6N2QxuVMMTUM6KC2ZEoYFdxkECApzvn9zqqq6yIts+XecYdFr57VC3hfX4SQo9I9wA== X-Received: by 2002:a5d:50cf:: with SMTP id f15mr11412163wrt.237.1633079862215; Fri, 01 Oct 2021 02:17:42 -0700 (PDT) Received: from ?IPV6:2001:b07:6468:f312:63a7:c72e:ea0e:6045? ([2001:b07:6468:f312:63a7:c72e:ea0e:6045]) by smtp.gmail.com with ESMTPSA id n186sm7166424wme.31.2021.10.01.02.17.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 01 Oct 2021 02:17:41 -0700 (PDT) Message-ID: <48151d08-ee29-2b98-b6e1-f3c8a1ff26bc@redhat.com> Date: Fri, 1 Oct 2021 11:17:33 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Subject: Re: [PATCH v8 7/7] KVM: x86: Expose TSC offset controls to userspace To: Marcelo Tosatti , Oliver Upton Cc: kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, Sean Christopherson , Marc Zyngier , Peter Shier , Jim Mattson , David Matlack , Ricardo Koller , Jing Zhang , Raghavendra Rao Anata , James Morse , Alexandru Elisei , Suzuki K Poulose , linux-arm-kernel@lists.infradead.org, Andrew Jones , Will Deacon , Catalin Marinas References: <20210916181538.968978-1-oupton@google.com> <20210916181538.968978-8-oupton@google.com> <20210930191416.GA19068@fuller.cnet> From: Paolo Bonzini In-Reply-To: <20210930191416.GA19068@fuller.cnet> Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=pbonzini@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20211001_021749_057914_CE287C45 X-CRM114-Status: GOOD ( 10.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 30/09/21 21:14, Marcelo Tosatti wrote: >> + new_off_n = t_0 + off_n + (k_1 - k_0) * freq - t_1 > Hi Oliver, > > This won't advance the TSC values themselves, right? Why not? It affects the TSC offset in the vmcs, so the TSC in the VM is advanced too. Paolo > This (advancing the TSC values by the realtime elapsed time) would be > awesome because TSC clock_gettime() vdso is faster, and some > applications prefer to just read from TSC directly. > See "x86: kvmguest: use TSC clocksource if invariant TSC is exposed". > > The advancement with this patchset only applies to kvmclock. > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel