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 3D87DCA553E for ; Thu, 14 Sep 2023 13:01:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238001AbjINNBq (ORCPT ); Thu, 14 Sep 2023 09:01:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44714 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237706AbjINNBn (ORCPT ); Thu, 14 Sep 2023 09:01:43 -0400 Received: from mail-wm1-x329.google.com (mail-wm1-x329.google.com [IPv6:2a00:1450:4864:20::329]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C307F1FDA for ; Thu, 14 Sep 2023 06:01:38 -0700 (PDT) Received: by mail-wm1-x329.google.com with SMTP id 5b1f17b1804b1-404539209ffso6419345e9.0 for ; Thu, 14 Sep 2023 06:01:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=citrix.com; s=google; t=1694696497; x=1695301297; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:references:cc:to :content-language:subject:from:user-agent:mime-version:date :message-id:from:to:cc:subject:date:message-id:reply-to; bh=ddiGkE6j5Yqjx2YChUyXAKUMjOfVYGR2wU1BDa/uOVM=; b=R/7QQUfIOihU7dGQ6BLubDNlHg4kFo2L3RePq6XZ9UzkbShQ72beoYkykdPtNO9ojO hOi7dAks7mgoG/wxJR4kvEWG1ZNr3QcSdYw4xWD4k3oDGO+9xgWVlnqXDnDxVQPu7jx3 FvCAIOzKqJjiMBjCK7g4R7Ctiafan+9onbcyE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1694696497; x=1695301297; h=content-transfer-encoding:in-reply-to:references:cc:to :content-language:subject:from:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=ddiGkE6j5Yqjx2YChUyXAKUMjOfVYGR2wU1BDa/uOVM=; b=gNB6eD69n0TEC+dIpigzRytvrgkJJ7nNhFnss46bn5XOgwpZUeATdHIzvsL+e+96fz p+ZtHqJ4PhRXsgFf00sBljXWIBQlnhk4tH5KxLrS6Fwg3U/W0miuC5/hgedmaar5R7cL OfdszQrDSQYv1kXqJlLsGFBmbDrZ9HO8FsbYs9ggzicdZwUzDwdUf0QZg5W14rzRGsih 11K/H2VmRzxXVWFDe33VFaicrZym83LU0nKQIY0G7f+gQmVyMYg/PG2v28U8rAHytM3E YfSzbxZ+BcaH7jarps7evp9xbJ2l/Be6WxLVNfc10MgQaclUOvuzNXLggTyT0QKbZjlr aFaA== X-Gm-Message-State: AOJu0YxKlvk2/O10N4xoNWIW61T9lDrHpIA+CLkqk13hK5j7nUjnp0ip FeDXydkOc/my3iKxbzo+6atKWg== X-Google-Smtp-Source: AGHT+IGu9ZokynanEidxo6b4ugwjHDqKzn9EMgeKgnKUXWugWLtEAMgf7RA8IhMPo5oq1q9TPG+E9Q== X-Received: by 2002:a05:600c:b5a:b0:401:eb0:a98d with SMTP id k26-20020a05600c0b5a00b004010eb0a98dmr4538194wmr.24.1694696496369; Thu, 14 Sep 2023 06:01:36 -0700 (PDT) Received: from [10.80.67.28] (default-46-102-197-194.interdsl.co.uk. [46.102.197.194]) by smtp.gmail.com with ESMTPSA id c20-20020a7bc854000000b003fee6f027c7sm4769165wml.19.2023.09.14.06.01.35 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 14 Sep 2023 06:01:35 -0700 (PDT) Message-ID: Date: Thu, 14 Sep 2023 14:01:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.15.1 From: andrew.cooper3@citrix.com Subject: Re: [PATCH v10 03/38] x86/msr: Add the WRMSRNS instruction support Content-Language: en-GB To: Juergen Gross , Xin Li , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-hyperv@vger.kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, luto@kernel.org, pbonzini@redhat.com, seanjc@google.com, peterz@infradead.org, ravi.v.shankar@intel.com, mhiramat@kernel.org, jiangshanlai@gmail.com References: <20230914044805.301390-1-xin3.li@intel.com> <20230914044805.301390-4-xin3.li@intel.com> <48d312f4-50cd-468d-af70-51314796b0d8@suse.com> In-Reply-To: <48d312f4-50cd-468d-af70-51314796b0d8@suse.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 14/09/2023 7:02 am, Juergen Gross wrote: > On 14.09.23 06:47, Xin Li wrote: >> Add an always inline API __wrmsrns() to embed the WRMSRNS instruction >> into the code. >> >> Tested-by: Shan Kang >> Signed-off-by: Xin Li > > In order to avoid having to add paravirt support for WRMSRNS I think > xen_init_capabilities() should gain: > > +    setup_clear_cpu_cap(X86_FEATURE_WRMSRNS); Xen PV guests will never ever see WRMSRNS.  Operating in CPL3, they have no possible way of adjusting an MSR which isn't serialising, because even the hypercall forms are serialising. Xen only exposes the bit for HVM guests. ~Andrew