From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757642AbdJMI7p (ORCPT ); Fri, 13 Oct 2017 04:59:45 -0400 Received: from mail-wm0-f48.google.com ([74.125.82.48]:45743 "EHLO mail-wm0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751468AbdJMI7m (ORCPT ); Fri, 13 Oct 2017 04:59:42 -0400 X-Google-Smtp-Source: AOwi7QBwvRIjcjnFfKbZ5TijSx7r04POEnuxlHKHk6b0ApyBAa3hY1OXw2xFSTx0LIvK/3A2/+40Cg== Date: Fri, 13 Oct 2017 10:59:47 +0200 From: Christoffer Dall To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: Julien Thierry , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org, marc.zyngier@arm.com, Russell King , Catalin Marinas , Will Deacon , open list Subject: Re: [PATCH v1 2/2] kvm: arm64: handle single-step of userspace mmio instructions Message-ID: <20171013085947.GE8927@cbox> References: <20171006113921.24880-1-alex.bennee@linaro.org> <20171006113921.24880-3-alex.bennee@linaro.org> <878tgoxudc.fsf@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <878tgoxudc.fsf@linaro.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 06, 2017 at 02:45:35PM +0100, Alex Bennée wrote: > > Julien Thierry writes: > > > On 06/10/17 12:39, Alex Bennée wrote: > >> The system state of KVM when using userspace emulation is not complete > >> until we return into KVM_RUN. To handle mmio related updates we wait > >> until they have been committed and then schedule our KVM_EXIT_DEBUG. > >> > >> I've introduced a new function kvm_arm_maybe_return_debug() to wrap up > >> the differences between arm/arm64 which is currently null for arm. > >> > >> Signed-off-by: Alex Bennée > >> --- > >> arch/arm/include/asm/kvm_host.h | 2 ++ > >> arch/arm64/include/asm/kvm_host.h | 1 + > >> arch/arm64/kvm/debug.c | 21 +++++++++++++++++++++ > >> arch/arm64/kvm/handle_exit.c | 9 +++------ > >> virt/kvm/arm/arm.c | 2 +- > >> virt/kvm/arm/mmio.c | 3 ++- > >> 6 files changed, 30 insertions(+), 8 deletions(-) > >> > >> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > >> index 4a879f6ff13b..aec943f6d123 100644 > >> --- a/arch/arm/include/asm/kvm_host.h > >> +++ b/arch/arm/include/asm/kvm_host.h > >> @@ -285,6 +285,8 @@ static inline void kvm_arm_init_debug(void) {} > >> static inline void kvm_arm_setup_debug(struct kvm_vcpu *vcpu) {} > >> static inline void kvm_arm_clear_debug(struct kvm_vcpu *vcpu) {} > >> static inline void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu) {} > >> +static inline int kvm_arm_maybe_return_debug(struct kvm_vcpu *vcpu, > >> + struct kvm_run *run) {} > >> > > > > This function should return 1. > > So I did ponder making this a bool, returning true if we need to exit > and testing in v/k/a/arm.c exit leg rather than in the mmio handler. > > At the moment it mirrors the existing exit logic which follows -1 err, 0 > return, >0 handled. But as I mentioned in the cover letter this fell > down a bit when dealing with the mmio case. > > > > >> int kvm_arm_vcpu_arch_set_attr(struct kvm_vcpu *vcpu, > >> struct kvm_device_attr *attr); > >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > >> index e923b58606e2..fa67d21662f6 100644 > >> --- a/arch/arm64/include/asm/kvm_host.h > >> +++ b/arch/arm64/include/asm/kvm_host.h > >> @@ -369,6 +369,7 @@ void kvm_arm_init_debug(void); > >> void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); > >> void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); > >> void kvm_arm_reset_debug_ptr(struct kvm_vcpu *vcpu); > >> +int kvm_arm_maybe_return_debug(struct kvm_vcpu *vcpu, struct kvm_run *run); > > > > I feel the name could be a little bit more explicit: > > > > kvm_arm_trap_need_step_debug, kvm_arm_trap_step_return_debug, > > kvm_arm_trap_need_return_debug. > > I wanted to keep the debug suffix so that's fine although I'm not so > sure trap is correct because on the tail end of mmio emulation are we > still trapping? > > Maybe kvm_arm_step_emulated_debug? I think you should name it: kvm_arm_should_complete_emulated_instr_debug() - or something better - and call it directly from kvm_arch_vcpu_ioctl_run, so that it becomes: ret = kvm_handle_mmio_return(vcpu, vcpu->run); if (ret) return ret; ret = kvm_arm_should_complete_emulated_instr_debug(vcpu); if (ret) return ret; > > > At least, I think it would be nice that the name reflect that this > > check is meant for emulated instructions. > > > > Otherwise: > > > > Reviewed-by: Julien Thierry > > > > Thanks, > > Thanks, -Christoffer