From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x225mM7SmdCfLi7Hpg6LCSL+bWso2PwxI+6CAt2APV1bfHtQfh2i/zW+5MXpqGFWwQM/9/pcA ARC-Seal: i=1; a=rsa-sha256; t=1517282030; cv=none; d=google.com; s=arc-20160816; b=e9Eo17y24viuW7PNMjv4TBiIDnalEODfNcUDE2kqmtZ4FrtyPn2/hvVKD56g98/Qj6 1qk1bF5/oUL7RA0S3bsixf4s7gy8n4+XdQCeVmGQreeqZOhMBGbWSe5fU1QwPUPmpkaf LfSFb2D4TNFl/tJZxVTwdLbN2At14GH0ezK+8CtBkfpZKLIxB1ifwIaeA2DD+nHw076p mqIlgxM4IOzDmpTVdS72ORR1eo15vz5jpMzQvouweUpKtrRWd1FNXVPEDgQWU3qI5Q+f jq2AeMa2PXkdStnTHJDXRS+iXcLE9/wAiT8FgHZBGjTBQoo6Koq5oE786HCs35nubCdD /56g== 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:arc-authentication-results; bh=cLt4KEus2VfTvuFltd+p+CF0iUBKyAHggB/keH9lCXE=; b=FoYxgvCq7HJTADSWnX+UUZeb5pZMu4u6C9sp0k01mhGWq56i4p+QEwe7HRlFBTixIg +G1DhVlDPqFpeWm2O4jC4agTCxvsNejdemugqqlvzOVaX+aw2nZ1rH34JpA2lwzaoH6W qUc+zz77p/aekl959cSt/M0Fvku1jm2gkJemBoskjwekbWD4pdAg7JcATy1gpZ1f5f6+ gmNMGeOwS5fYTzhVaKngEwE/B5uOAGoMd41/qOmb2N+9oXgH0nJArEzrmqQhJRwHxAHJ ESQcNHHBEnlg347z0wb9YYbRsVjcNrwU2tgHgqTFLgQQe6s4ND5T5o40p8XZRlIPbVOS uxhw== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of ak@linux.intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=ak@linux.intel.com Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of ak@linux.intel.com designates 192.55.52.93 as permitted sender) smtp.mailfrom=ak@linux.intel.com X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,433,1511856000"; d="scan'208";a="199826213" Date: Mon, 29 Jan 2018 19:13:40 -0800 From: Andi Kleen To: Jim Mattson Cc: Linus Torvalds , David Woodhouse , Arjan van de Ven , Eduardo Habkost , KarimAllah Ahmed , Linux Kernel Mailing List , Andrea Arcangeli , Andy Lutomirski , Ashok Raj , Asit Mallick , Borislav Petkov , Dan Williams , Dave Hansen , Greg Kroah-Hartman , "H . Peter Anvin" , Ingo Molnar , Janakarajan Natarajan , Joerg Roedel , Jun Nakajima , Laura Abbott , Masami Hiramatsu , Paolo Bonzini , Peter Zijlstra , Radim =?utf-8?B?S3LEjW3DocWZ?= , Thomas Gleixner , Tim Chen , Tom Lendacky , KVM list , the arch/x86 maintainers , "Dr. David Alan Gilbert" Subject: Re: [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure Message-ID: <20180130031340.GV26209@tassilo.jf.intel.com> References: <1516476182-5153-6-git-send-email-karahmed@amazon.de> <20180129201404.GA1588@localhost.localdomain> <1517257022.18619.30.camel@infradead.org> <20180129204256.GV25150@localhost.localdomain> <31415b7f-9c76-c102-86cd-6bf4e23e3aee@linux.intel.com> <1517259759.18619.38.camel@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.9.1 (2017-09-22) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1590140581449802182?= X-GMAIL-MSGID: =?utf-8?q?1590985522533089385?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: > Right now, we are dealing with one workaround, which is tied to > Skylake-era model numbers. Yes, we could report a Skylake model > number, and Linux guests would use IBRS instead of retpoline. But this Nobody is planning to use IBRS and Linus has rejected it. > approach doesn't scale. What happens when someone introduces a > workaround tied to some other model numbers? There are already many of those in the tree for other issues and features. So far you managed to survive without. Likely that will be true in the future too. -Andi