From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227lF+aCSznppLtcxxJCmPwBKzjQ2KKv0bRCJhro1/g8CRwJrnVVKKxchM0QMnzdEi5NqGHC ARC-Seal: i=1; a=rsa-sha256; t=1516877685; cv=none; d=google.com; s=arc-20160816; b=KdCYZ0HNYOO1rSZg61nLjeGuHvfwVYHAsVx0RQhPuReo4AdGJd0J6BDCHfSHsY8X+c xSq4mRBd0t14WGnL+XCmf0niOvU5tBnQw+Snx6yTiX9rdwx6vMVNGDhA6enBufim0hcb 1lYe6qkPXw/roFZnoz1XgfKithpmxfPcGkiuKmi9Wn87RyHQv0G4NDLbKRapoER+jDjZ G0nuhPBHEeknEDXFC+3YTxHp/RFEQlUkjWEmYMTZxLei7YmvEvBeryVwvxISAWI1y4He hmAJEL3PTKI7UYWy6Gxj25H7WKQWZg/JD70tP/M2Xi1f6JAA6XMTe18HYG2kJO4xUPel 2hOQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:message-id:in-reply-to:subject :cc:to:from:date:arc-authentication-results; bh=qCzbBlKWLFo+LW/VSKNmfotGHSQXdjA3FCkKn65JqF4=; b=MMP6tNnzKF/3vd7SbbDMclZmfZRT8flA4oKfSOvVSTsVyuCstoGLcOQCAcw5SVEc6V xHFJbh7Y3Iqfnu3RQ8X4giO1Hxnc+B0yaTTe1hJBSdvQy0etheyEuTF9M6RhfAuMarsP mw2Flu6DwncKA6NAZfv5izGUL9aIShli7O1tsXLirAsAfa+9I2YgC16MjDADeI8wUG1U l4cA57Xr9yl9/9NKci6C6OYZYfLyte30giVvoFsK6SJjQvon9fxkGj6aFatphaR7PR/z 1a2r6sMWPfeqp7r9fQZlnGz20MS9dBGwBsyU7ZyCn9U0qkmgZLC9gqiYMbyoekVBbIac 4tXw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a01:7a0:2:106d:700::1 as permitted sender) smtp.mailfrom=tglx@linutronix.de Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of tglx@linutronix.de designates 2a01:7a0:2:106d:700::1 as permitted sender) smtp.mailfrom=tglx@linutronix.de Date: Thu, 25 Jan 2018 11:54:20 +0100 (CET) From: Thomas Gleixner To: David Woodhouse cc: arjan@linux.intel.com, karahmed@amazon.de, x86@kernel.org, linux-kernel@vger.kernel.org, tim.c.chen@linux.intel.com, bp@alien8.de, peterz@infradead.org, pbonzini@redhat.com, ak@linux.intel.com, torvalds@linux-foundation.org, gregkh@linux-foundation.org, dave.hansen@intel.com, gnomes@lxorguk.ukuu.org.uk, ashok.raj@intel.com, mingo@kernel.org Subject: Re: [PATCH v4 6/7] x86/cpufeature: Blacklist SPEC_CTRL on early Spectre v2 microcodes In-Reply-To: <1516876994.30244.51.camel@infradead.org> Message-ID: References: <1516872189-16577-1-git-send-email-dwmw@amazon.co.uk> <1516872189-16577-7-git-send-email-dwmw@amazon.co.uk> <1516876994.30244.51.camel@infradead.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: multipart/mixed; BOUNDARY="8323329-1455264887-1516877661=:2020" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590555855308082400?= X-GMAIL-MSGID: =?utf-8?q?1590561536689722456?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1455264887-1516877661=:2020 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Thu, 25 Jan 2018, David Woodhouse wrote: > On Thu, 2018-01-25 at 09:23 +0000, David Woodhouse wrote: > > > > +/* > > + * Early microcode releases for the Spectre v2 mitigation were broken. > > + * Information taken from; > > + * • https://newsroom.intel.com/wp-content/uploads/sites/11/2018/01/microcode-update-guidance.pdf > > Oh look, Intel have released a *third* version of that document > already, and they've bumped the bad Kabylake versions to 0x84, although > they're *still* missing out the KBL 906EA SKU which was updated to 0x80 > in the public 20180108 microcode release. I'll bump them all in my tree > to 0x84. > > Thomas, want another copy in email now, or were we waiting for another > round of these before you merge them anyway? Looking at this mess makes me even less convinced that a blacklist is a good idea. We have already at least 3 different variants of blacklists. So I rather see a whitelist approach which says: if (ucode_version < known_good(family, model)) return; I know it would require that Intel releases a set of known good ucodes at some point in the future, but that's a reasonable request. I rather take a few patches which add the cutoff for family/model (and NO, I don't want to add stepping into the mix at all) than having this blacklist mess which keeps changing every other day. Thanks, tglx --8323329-1455264887-1516877661=:2020--