From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227TPous0TYEssdX88pI7boqq8rtze6MX3/smsnI3BIWo4Jny56kOLets8lTWk2JlG/RxpxW ARC-Seal: i=1; a=rsa-sha256; t=1517274780; cv=none; d=google.com; s=arc-20160816; b=g1rulQw3TA7WECVAyHS2lhW3fFjUMqb8UdKJLNxMJh8vt+J9/vcwiVsikx3RN2LJRZ ZbK40YxactNuUe4tOv6a4p/U8/lA4CoRUoblx1G2fHSo/o4Lfq9wgXELVag/m3jeDVtI y7sD7F+z7cJydsz98dGv+Om0tFKvxamYcXMZ/oqa5DVl52yiiOFKWRU179qBS17+Djqq 5mqjLh4OInxLntSx4SlqmbDDZiKflCFoVxXQ57VorpsPHCNqoz7pDuQoIeghA7YaFNQJ WOcx3ZN37C0h8iXEXcoNIHDdg2Uww3F1t47PQzVHkk6sIWqNsNcA5V51Pr3/Gr0Azg0A 1fTg== 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=0B7UGzU5hVqCk0kfPGyJB4WISqPQrdDqEyB5n2VUKOY=; b=R2AkxjqE2V5iMPd+dJ2M7dREm6iLdn2uj1NfFvNqkn79/YzcWMHuV47NPwoleKXsZw /oaX58eJfQ0bNFQaXzmO2+gGJX3QVxGMAOXqjrtUi4FscQGZcuyFUhA4hnWSGgyFoqc1 NXzekFJmLLJL14sJTLBA8UQnuneBmQkFun2Nh5o5goLCrmiA1SoOzuQB7+Zdp4JiykSx UXYqqFfh3yKYdaiWu6enkAjIc9cqhpCyv7xbyvq4bIQdFDrKBpOCjX94feE+tSFRd/mW 7YfHVrWh7dNcnbDtzewwnhb+9YQnmTufxAM2DozWu/FtBH/5JqK5ISOkk3UHZhd4J8xP EsbA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of ehabkost@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=ehabkost@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of ehabkost@redhat.com designates 209.132.183.28 as permitted sender) smtp.mailfrom=ehabkost@redhat.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Date: Mon, 29 Jan 2018 23:12:58 -0200 From: Eduardo Habkost To: Konrad Rzeszutek Wilk Cc: David Woodhouse , Arjan van de Ven , KarimAllah Ahmed , linux-kernel@vger.kernel.org, Andi Kleen , 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 , Linus Torvalds , Masami Hiramatsu , Paolo Bonzini , Peter Zijlstra , Radim =?utf-8?B?S3LEjW3DocWZ?= , Thomas Gleixner , Tim Chen , Tom Lendacky , kvm@vger.kernel.org, x86@kernel.org, "Dr. David Alan Gilbert" Subject: Re: [RFC,05/10] x86/speculation: Add basic IBRS support infrastructure Message-ID: <20180130011258.GC21702@localhost.localdomain> 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> <20180129214421.GW25150@localhost.localdomain> <20180129221011.GW22045@char.us.oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180129221011.GW22045@char.us.oracle.com> X-Fnord: you can see the fnord 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?1590977920855600674?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Mon, Jan 29, 2018 at 05:10:11PM -0500, Konrad Rzeszutek Wilk wrote: [...] > The migration code could be 'tickled' (when arrived at the destination) > to recheck the CPUID and do the alternative logic to turn the > proper bits on. > > And this tickling could be as simple as an ACPI DSDT/AML code > specific to KVM PnP devices (say the CPUs?) to tell the guest to > resample its environment? This would be nice to have for other CPU features, but if I understood a previous message from Andi on this thread correctly, it wouldn't be useful for the Spectre mitigations. -- Eduardo