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([2.223.46.215]) by smtp.gmail.com with ESMTPSA id l17-20020a7bc451000000b003fc17e8a1efsm6700834wmi.45.2023.07.28.04.45.54 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 28 Jul 2023 04:45:54 -0700 (PDT) X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: 4fd1960c-2d3c-11ee-b24d-6b7b168915f2 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloud.com; s=cloud; t=1690544755; x=1691149555; h=in-reply-to:content-disposition:mime-version:references:subject:cc :to:from:date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=fRhkSPt9qHiPgYCQ1t3y4EbA5p/iqPHwLpK8iS+NFhw=; b=c904X/u4C3i/J0t8RHh0JGgQQ0rlgrGjXSd7RFQgpArsleRTYCJxcEAplsQ1zjyjsT PjKTMY2lw7xU1yp0S2S8gKmn7UjJjac6KWEP+cKs+8ZkTE3CAgNk9idI+2mbMG2qj79M fStqgdnNyQnf5ItzcdKvjpzoeOdOO8j6kvazo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690544755; x=1691149555; h=in-reply-to:content-disposition:mime-version:references:subject:cc :to:from:date:message-id:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=fRhkSPt9qHiPgYCQ1t3y4EbA5p/iqPHwLpK8iS+NFhw=; b=G7c/tLFOwjAaCf1y7vZv4LDJ7aOSJkSNlSnehOKY2D6foWC87ocpDXosZIn7aIoCu4 8K3IJM47NL1zIQdfz8h4h0aKQzfQev3aOgqD0hprq/5i+8N5z+ObLk8/iRHGpCT4+IDj 2BKBt0ffC2uUZpVda3i3OZ9/0/0t3Vdtl4TfRl9TcJKiwCHBkzVfyGRUs2CwaGrCSk3h z7lcMpXe+34EjXILSy5UoXD529bDmE7a4UNyZve4KAClypNSEkbUiA+Vn0NHxNdrCmD/ FqeTbUVgDnZgdVYNMvGo5yWDzd+H+voWVTxqnz4kprmxYMj7/kZqrgay+sLgXXh0yyoj UD1Q== X-Gm-Message-State: ABy/qLafflbW0yLr1Og6ShU/fshlKbbyCHXVgiKNKTptpureEgH/T+tQ Br2OPx4qVUbeadXJtztOck78hA== X-Google-Smtp-Source: APBJJlFu5CYyX94g0/93Uwds26/Ul2qwddVw7oSE33NERPqjn76D3S5XW53h1ILrIj65T14QjBiQHQ== X-Received: by 2002:a05:6512:2034:b0:4fe:e8f:e216 with SMTP id s20-20020a056512203400b004fe0e8fe216mr1376382lfs.39.1690544755077; Fri, 28 Jul 2023 04:45:55 -0700 (PDT) Message-ID: <64c3aa72.7b0a0220.ec31.f864@mx.google.com> X-Google-Original-Message-ID: Date: Fri, 28 Jul 2023 12:45:44 +0100 From: Alejandro Vallejo To: Jan Beulich Cc: Andrew Cooper , Roger Pau =?iso-8859-1?Q?Monn=E9?= , Wei Liu , Xen-devel Subject: Re: [PATCH v6 1/3] x86/microcode: Ignore microcode loading interface for revision = -1 References: <20230724165235.25262-1-alejandro.vallejo@cloud.com> <20230724165235.25262-2-alejandro.vallejo@cloud.com> <4a31893d-a784-ed33-bd47-5db85b3c02b6@suse.com> <64bfc52e.050a0220.14646.cb0d@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <64bfc52e.050a0220.14646.cb0d@mx.google.com> On Tue, Jul 25, 2023 at 01:50:52PM +0100, Alejandro Vallejo wrote: > On Tue, Jul 25, 2023 at 08:40:31AM +0200, Jan Beulich wrote: > > > --- a/xen/arch/x86/cpu/microcode/core.c > > > +++ b/xen/arch/x86/cpu/microcode/core.c > > > @@ -867,10 +867,23 @@ int __init early_microcode_init(unsigned long *module_map, > > > return -ENODEV; > > > } > > > > > > - microcode_grab_module(module_map, mbi); > > > - > > > ucode_ops.collect_cpu_info(); > > > > > > + /* > > > + * Some hypervisors deliberately report a microcode revision of -1 to > > > + * mean that they will not accept microcode updates. We take the hint > > > + * and ignore the microcode interface in that case. > > > + */ > > > + if ( this_cpu(cpu_sig).rev == ~0 ) > > > + { > > > + printk(XENLOG_INFO "Microcode loading disabled due to: %s", > > > [snip] > > > As it stands this message > > will be invisible by default. > Arguably, that's not necessarily a bad thing. The fact that microcode > cannot be updated is expected behaviour and it makes little sense to warn > about it. If only because they should already be aware of it through their > agreement with their provider. > > The case I can think of where a warning would be sensible is where the > system has a microcode blob more recent than the currently installed > revision. This is something the admin may want to be aware of in order to > pester their provider for updates. In the common case the machine won't > even need such an update, so sending unconditional warnings per boot seems > unwarranted. Actually, the previous message probably ought to be an INFO too. It's an unconditional warning on old AMD and anything non AMD/Intel for no good reason. Alejandro