From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752836AbeBKKTb (ORCPT ); Sun, 11 Feb 2018 05:19:31 -0500 Received: from mail-wr0-f193.google.com ([209.85.128.193]:36521 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752288AbeBKKT3 (ORCPT ); Sun, 11 Feb 2018 05:19:29 -0500 X-Google-Smtp-Source: AH8x224z4Ln+w4iGquHUHBz/MstgqzGwHMUiplZsxGKfYT1+yVgBSe4MYx95dbX6nqtJh4iq/Kx8cA== Date: Sun, 11 Feb 2018 11:19:24 +0100 From: Ingo Molnar To: David Woodhouse Cc: tglx@linutronix.de, karahmed@amazon.de, sironi@amazon.de, x86@kernel.org, kvm@vger.kernel.org, torvalds@linux-foundation.org, pbonzini@redhat.com, linux-kernel@vger.kernel.org, bp@alien8.de, peterz@infradead.org, jmattson@google.com, rkrcmar@redhat.com, arjan.van.de.ven@intel.com, dave.hansen@intel.com Subject: Re: [PATCH v2 5/6] KVM/nVMX: Set the CPU_BASED_USE_MSR_BITMAPS if we have a valid L02 MSR bitmap Message-ID: <20180211101924.vztfslwqoh7km6q2@gmail.com> References: <1518305967-31356-1-git-send-email-dwmw@amazon.co.uk> <1518305967-31356-6-git-send-email-dwmw@amazon.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1518305967-31356-6-git-send-email-dwmw@amazon.co.uk> User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * David Woodhouse wrote: > From: KarimAllah Ahmed > > We either clear the CPU_BASED_USE_MSR_BITMAPS and end up intercepting all > MSR accesses or create a valid L02 MSR bitmap and use that. This decision > has to be made every time we evaluate whether we are going to generate the > L02 MSR bitmap. > > Before commit 086e7d4118cc ("KVM: VMX: Allow direct access to MSR_IA32_SPEC_CTRL") > this was probably OK since the decision was always identical. This is no > longer the case now since the MSR bitmap might actually change once we > decide to not intercept SPEC_CTRL and PRED_CMD. Note, I fixed the changelog to refer to the correct upstream SHA1, which is: d28b387fb74d: KVM/VMX: Allow direct access to MSR_IA32_SPEC_CTRL Thanks, Ingo