From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x224UBYxmzfd43cyxVA3b0wAnIhG5pLwFzsnipMQKaLyuwdsqe+oFfQISXPeuhDTLc+LVLrIE ARC-Seal: i=1; a=rsa-sha256; t=1518810449; cv=none; d=google.com; s=arc-20160816; b=QFfxeGrJFZItLdnYus3PG5D/GVVUj43lq0WH/yFRdLIFE5JuA6jKbFuvLY0UmK4ufd 1ZqRR1Pi6bTe5tXRgvzhS/1WA1hOTukVhCszNrKTkBQLNIgGJwlznsw/UQANpzW25sii 2Xwe9f1LJdFsvYvQ8iwb0E0mjRHalR6Uxy8v7pZjiclvEzzpoJhrqFfcwsGxG9Y35aNK MPMasmcwUjfGRauwB0yb8ERdrr6aoCAReZqy8x9ltScEYIpoyUM34v9EiN1Y8EPOK0EU J5PU6Yg7XTAL2q0aDPP8M02CUFnt2VafyCHWI4nwPtC9t6d2Xdz1F8OKvKwU/oNZHxBL P+Fw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:from:references:cc:to:subject :arc-authentication-results; bh=rdwh/m07IPZHRS91jU42oWhhqdviohtiHozSq/i2Xro=; b=SDIMkjyb4XH+vopwdfT4cKie/zsvLtvnTDHJ7KUCf/JL3aeaCMPWvuYzwqRKeYDpaj /gVd9gs+vIFStrbgvGqCfScUbXaxuqcYkjmW4E80OGCfzuIMYW3XXodg2h4ADQzTgpQy q1TtuIFCUtObQtjJr1voLV6ZnvQlkbpLiwqWA8BidJZh4PMMpEFNyYCO9rDL2L6eX5KE NrJXBF1/a4jNPRo6LzlhzyalE6MBSrRwY6M0YhRP+RSXTK3JvEX3URxW4w7kxff+Bhqo RVCaJhmttnMkExVlrcAnbA6TUI6QJjiNs883FVKoEM1YgwxoTZBgmOL/1zvYgeJuoKTi Pm3Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of arjan@linux.intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=arjan@linux.intel.com Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of arjan@linux.intel.com designates 192.55.52.120 as permitted sender) smtp.mailfrom=arjan@linux.intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,520,1511856000"; d="scan'208";a="20762629" Subject: Re: [RFC][PATCH] x86: proposed new ARCH_CAPABILITIES MSR bit for RSB-underflow To: Linus Torvalds , Dave Hansen Cc: Linux Kernel Mailing List , Thomas Gleixner , One Thousand Gnomes , Rik van Riel , Josh Poimboeuf , Tom Lendacky , Peter Zijlstra , Jiri Kosina , Andy Lutomirski , Kees Cook , Greg Kroah-Hartman , Paul Turner , David Woodhouse , the arch/x86 maintainers , Andi Kleen , Tim Chen , Dan Williams , "Mallick, Asit K" References: <20180216191755.6F62DDEA@viggo.jf.intel.com> From: Arjan van de Ven Message-ID: <768f3a56-28b0-91a1-f555-94e64a146abc@linux.intel.com> Date: Fri, 16 Feb 2018 11:47:27 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1592586608850569551?= X-GMAIL-MSGID: =?utf-8?q?1592588185731160718?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On 2/16/2018 11:43 AM, Linus Torvalds wrote: > On Fri, Feb 16, 2018 at 11:38 AM, Linus Torvalds > wrote: >> >> Of course, your patch still doesn't allow for "we claim to be skylake >> for various other independent reasons, but the RSB issue is fixed". > > .. maybe nobody ever has a reason to do that, though? yeah I would be extremely surprised > > Who knows, virtualization people may simply want the user to specify > the model, but then make the Spectre decisions be based on actual > hardware capabilities (whether those are "current" or "some minimum > base"). once you fake to be skylake when you're not, you do that for a reason; normallyt that reason is that you COULD migrate to a skylake. (and migration is not supposed to be visble to the guest OS) and at that point you are a skylake for all intents and purposes. (and the virtualization people also really hate it when the hardware burst the bubble of this fakeing hardware to be not what it is)