From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x2277oMcO8yR16hC3kH2IlBZJx9uZCPkYkS6fT2Xa0A4XceebjP+hpv8XUV97GH8IXq4uJ3DB ARC-Seal: i=1; a=rsa-sha256; t=1516611390; cv=none; d=google.com; s=arc-20160816; b=oygVeQPPs+w5HH2WFQlAwGFdeG3uuJyuO81PjtUytUBo3bnDyuIhe/bv6msV3G7N7r Sh98IQCMwAtab+A6MNNPEnDNBE5Y/LOiwjMFdYZLOahT4RgIcEsDmjhQv/sXg8tm+zVV c2yxGoOnFoXonKuv78dKIH4c9Uk3bSkz1bnotcBW5vVEzj3oufkR9ccCPRwPTGmhiMlN +xP0kcdUX85HuZc79Zme/OC8cbYhOhQWNkPV/s1PvtJCYxETmpg1hoYR8nyhHdHOVCks 9ORPnqRDuiod/u/JiTtjTpK8s1cACdORYxUtWvRBkbhRKxMqcONa+6pC6cw7GXxGUzEm aynA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=rY4rW4H/yaBeGxA9r4Nd/7ZSY9kiLMPzXIKaw25XXKc=; b=H6M1atZbbNCW3dV1dDPTkPIuJ2WfcLBQ8GQhYqlNEvpZzhMN2UeqFXuZd4sFracdCl wSLWEumtlzjTtHLjAbPLSGB4uTr2Z2SHRj046s150Hta0WyZ1vvagRxS+Sf8x8W3tg89 2Y5SpQcoH2u3xAyhjqGXEnCpZRq9/blg2j3SOlI+Ec2LJt/TYaHnJw/GNVYUcy4ZoWJF DTk1dFQ0GqOASJFLgWjTK+ofRuovtJbicDzN7eWaZfhrfUXHJExP62sMeTmBjswbXxqF EPaLwbyjL4aNrqFO5UMI49UQAKtoXo8qCyXGA8+4c16OLQOMOFfCY+8uQ4RZOKt5uYQj QEuw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=R6RaU3VK; spf=pass (google.com: domain of joro@8bytes.org designates 2a01:238:4383:600:38bc:a715:4b6d:a889 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Authentication-Results: mx.google.com; dkim=pass (test mode) header.i=@8bytes.org header.s=mail-1 header.b=R6RaU3VK; spf=pass (google.com: domain of joro@8bytes.org designates 2a01:238:4383:600:38bc:a715:4b6d:a889 as permitted sender) smtp.mailfrom=joro@8bytes.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=8bytes.org Date: Mon, 22 Jan 2018 09:56:25 +0100 From: Joerg Roedel To: Nadav Amit Cc: Thomas Gleixner , Ingo Molnar , "H . Peter Anvin" , the arch/x86 maintainers , LKML , "open list:MEMORY MANAGEMENT" , Linus Torvalds , Andy Lutomirski , Dave Hansen , Josh Poimboeuf , Juergen Gross , Peter Zijlstra , Borislav Petkov , Jiri Kosina , Boris Ostrovsky , Brian Gerst , David Laight , Denys Vlasenko , Eduardo Valentin , Greg KH , Will Deacon , aliguori@amazon.com, daniel.gruss@iaik.tugraz.at, hughd@google.com, keescook@google.com, Andrea Arcangeli , Waiman Long , jroedel@suse.de Subject: Re: [RFC PATCH 00/16] PTI support for x86-32 Message-ID: <20180122085625.GE28161@8bytes.org> References: <1516120619-1159-1-git-send-email-joro@8bytes.org> <5D89F55C-902A-4464-A64E-7157FF55FAD0@gmail.com> <886C924D-668F-4007-98CA-555DB6279E4F@gmail.com> <9CF1DD34-7C66-4F11-856D-B5E896988E16@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9CF1DD34-7C66-4F11-856D-B5E896988E16@gmail.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1589767841591470697?= X-GMAIL-MSGID: =?utf-8?q?1590282303497626901?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: Hey Nadav, On Sun, Jan 21, 2018 at 03:46:24PM -0800, Nadav Amit wrote: > It does seem that segmentation provides sufficient protection from Meltdown. Thanks for testing this, if this turns out to be true for all affected uarchs it would be a great and better way of protection than enabling PTI. But I'd like an official statement from Intel on that one, as their recommended fix is still to use PTI. And as you said, if it turns out that this works only on some Intel uarchs, we can also detect it at runtime and then chose the fasted meltdown protection mechanism. Thanks, Joerg