Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751733AbeAIId4 (ORCPT + 1 other); Tue, 9 Jan 2018 03:33:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:44322 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751428AbeAIIdw (ORCPT ); Tue, 9 Jan 2018 03:33:52 -0500 Subject: Re: [PATCH 4/7] kvm: vmx: Set IBPB when running a different VCPU To: Jim Mattson Cc: LKML , kvm list , aliguori@amazon.com, Tom Lendacky , dwmw@amazon.co.uk, bp@alien8.de, Tim Chen References: <1515434925-10250-1-git-send-email-pbonzini@redhat.com> <1515434925-10250-5-git-send-email-pbonzini@redhat.com> From: Paolo Bonzini Message-ID: <1fadc48d-78b9-a26a-3ca9-b3fb7898b33a@redhat.com> Date: Tue, 9 Jan 2018 09:33:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.5.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 09 Jan 2018 08:33:52 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 08/01/2018 20:36, Jim Mattson wrote: > Shouldn't there be an IBPB on *any* context switch away from a VCPU > thread, even if it is to a non-VCPU thread? Yes, but that's the task of patches to the generic Linux context switching code. As mentioned in the cover letter, this isn't yet a full solution---just the KVM bits, which is what Radim and I have full control on. Hence the hacks with cpuid in local bools. Paolo