From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757554AbcAYQhq (ORCPT ); Mon, 25 Jan 2016 11:37:46 -0500 Received: from foss.arm.com ([217.140.101.70]:39228 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757461AbcAYQhm (ORCPT ); Mon, 25 Jan 2016 11:37:42 -0500 Subject: Re: [PATCH v2 00/21] arm64: Virtualization Host Extension support To: Will Deacon References: <1453737235-16522-1-git-send-email-marc.zyngier@arm.com> <20160125162613.GD22927@arm.com> Cc: Catalin Marinas , Christoffer Dall , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu From: Marc Zyngier Organization: ARM Ltd Message-ID: <56A64F53.4000201@arm.com> Date: Mon, 25 Jan 2016 16:37:39 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Icedove/38.5.0 MIME-Version: 1.0 In-Reply-To: <20160125162613.GD22927@arm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/01/16 16:26, Will Deacon wrote: > On Mon, Jan 25, 2016 at 03:53:34PM +0000, Marc Zyngier wrote: >> ARMv8.1 comes with the "Virtualization Host Extension" (VHE for >> short), which enables simpler support of Type-2 hypervisors. >> >> This extension allows the kernel to directly run at EL2, and >> significantly reduces the number of system registers shared between >> host and guest, reducing the overhead of virtualization. >> >> In order to have the same kernel binary running on all versions of the >> architecture, this series makes heavy use of runtime code patching. >> >> The first 20 patches massage the KVM code to deal with VHE and enable >> Linux to run at EL2. The last patch catches an ugly case when VHE >> capable CPUs are paired with some of their less capable siblings. This >> should never happen, but hey... >> >> I have deliberately left out some of the more "advanced" >> optimizations, as they are likely to distract the reviewer from the >> core infrastructure, which is what I care about at the moment. >> >> A few things to note: >> >> - Given that the code has been almost entierely rewritten, I've >> dropped all Acks from the new patches >> >> - GDB is currently busted on VHE systems, as it checks for version 6 >> on the debug architecture, while VHE is version 7. The binutils >> people are on the case. > > [...] > >> arch/arm/include/asm/virt.h | 5 ++ >> arch/arm/kvm/arm.c | 151 +++++++++++++++++++------------ >> arch/arm/kvm/mmu.c | 7 ++ >> arch/arm64/Kconfig | 13 +++ >> arch/arm64/include/asm/cpufeature.h | 3 +- >> arch/arm64/include/asm/kvm_arm.h | 1 + >> arch/arm64/include/asm/kvm_emulate.h | 3 + >> arch/arm64/include/asm/kvm_mmu.h | 34 ++++++- >> arch/arm64/include/asm/virt.h | 27 ++++++ >> arch/arm64/kernel/asm-offsets.c | 3 - >> arch/arm64/kernel/cpufeature.c | 15 +++- >> arch/arm64/kernel/head.S | 51 ++++++++++- >> arch/arm64/kernel/smp.c | 3 + >> arch/arm64/kvm/hyp-init.S | 18 +--- >> arch/arm64/kvm/hyp.S | 7 ++ >> arch/arm64/kvm/hyp/entry.S | 6 ++ >> arch/arm64/kvm/hyp/hyp-entry.S | 107 +++++++--------------- >> arch/arm64/kvm/hyp/hyp.h | 119 ++++++++++++++++++++++-- >> arch/arm64/kvm/hyp/switch.c | 170 +++++++++++++++++++++++++++++++---- >> arch/arm64/kvm/hyp/sysreg-sr.c | 147 ++++++++++++++++++++---------- >> arch/arm64/kvm/hyp/timer-sr.c | 10 +-- >> drivers/clocksource/arm_arch_timer.c | 96 ++++++++++++-------- >> 22 files changed, 724 insertions(+), 272 deletions(-) > > Have you tried hw_breakpoint/perf/ptrace with these changes? I was under > the impression that the debug architecture was aware of E2H and did need > some changes made. I know you say that GDB is broken anyway, but we should > check that the kernel does the right thing if userspace pokes it the > right way. I did use HW breakpoints on the model by hacking the host kernel to return Debug Version 6 instead of 7, and things seem to work as expected. strace also works out of the box. As for perf, did you have something precise in mind? Thanks, M. -- Jazz is not dead. It just smells funny...