From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752715AbdKWMiy (ORCPT ); Thu, 23 Nov 2017 07:38:54 -0500 Received: from mail-wm0-f67.google.com ([74.125.82.67]:39630 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751968AbdKWMiw (ORCPT ); Thu, 23 Nov 2017 07:38:52 -0500 X-Google-Smtp-Source: AGs4zMZnPr0W9/0FxH633rE6AEiVipdBNKunNCpqbTae6r3ls53dpTXOGDaJcZBko8ugeLuDTNrjQg== Date: Thu, 23 Nov 2017 13:39:01 +0100 From: Christoffer Dall To: Alex =?iso-8859-1?Q?Benn=E9e?= Cc: julien.thierry@arm.com, kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, christoffer.dall@linaro.org, marc.zyngier@arm.com, Catalin Marinas , Will Deacon , Dave Martin , James Morse , open list Subject: Re: [PATCH v1 2/2] kvm: arm64: handle single-step of hyp emulated mmio instructions Message-ID: <20171123123901.GZ28855@cbox> References: <20171123121134.11050-1-alex.bennee@linaro.org> <20171123121134.11050-3-alex.bennee@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20171123121134.11050-3-alex.bennee@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 Thu, Nov 23, 2017 at 12:11:34PM +0000, Alex Bennée wrote: > There is a fast-path of MMIO emulation inside hyp mode. The handling > of single-step is broadly the same as kvm_arm_handle_step_debug() > except we just setup ESR/HSR so handle_exit() does the correct thing > as we exit. > > For the case of an emulated illegal access causing an SError we will > exit via the ARM_EXCEPTION_EL1_SERROR path in handle_exit(). We behave > as we would during a real SError and clear the DBG_SPSR_SS bit for the > emulated instruction. > > Signed-off-by: Alex Bennée > --- > arch/arm64/kvm/hyp/switch.c | 37 ++++++++++++++++++++++++++++++------- > 1 file changed, 30 insertions(+), 7 deletions(-) > > diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c > index 525c01f48867..f7c651f3a8c0 100644 > --- a/arch/arm64/kvm/hyp/switch.c > +++ b/arch/arm64/kvm/hyp/switch.c > @@ -22,6 +22,7 @@ > #include > #include > #include > +#include > > static bool __hyp_text __fpsimd_enabled_nvhe(void) > { > @@ -269,7 +270,11 @@ static bool __hyp_text __populate_fault_info(struct kvm_vcpu *vcpu) > return true; > } > > -static void __hyp_text __skip_instr(struct kvm_vcpu *vcpu) > +/* Skip an instruction which has been emulated. Returns true if > + * execution can continue or false if we need to exit hyp mode because > + * single-step was in effect. > + */ > +static bool __hyp_text __skip_instr(struct kvm_vcpu *vcpu) > { > *vcpu_pc(vcpu) = read_sysreg_el2(elr); > > @@ -282,6 +287,14 @@ static void __hyp_text __skip_instr(struct kvm_vcpu *vcpu) > } > > write_sysreg_el2(*vcpu_pc(vcpu), elr); > + > + if (vcpu->guest_debug & KVM_GUESTDBG_SINGLESTEP) { > + vcpu->arch.fault.esr_el2 = > + (ESR_ELx_EC_SOFTSTP_LOW << ESR_ELx_EC_SHIFT) | 0x22; > + return false; > + } else { > + return true; > + } > } > > int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) > @@ -342,13 +355,21 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) > int ret = __vgic_v2_perform_cpuif_access(vcpu); > > if (ret == 1) { > - __skip_instr(vcpu); > - goto again; > + if (__skip_instr(vcpu)) > + goto again; > + else > + exit_code = ARM_EXCEPTION_TRAP; > } > > if (ret == -1) { > - /* Promote an illegal access to an SError */ > - __skip_instr(vcpu); > + /* Promote an illegal access to an > + * SError. If we would be returning > + * due to single-step clear the SS > + * bit so handle_exit knows what to > + * do after dealing with the error. > + */ > + if (!__skip_instr(vcpu)) > + *vcpu_cpsr(vcpu) &= ~DBG_SPSR_SS; > exit_code = ARM_EXCEPTION_EL1_SERROR; > } > > @@ -363,8 +384,10 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu) > int ret = __vgic_v3_perform_cpuif_access(vcpu); > > if (ret == 1) { > - __skip_instr(vcpu); > - goto again; > + if (__skip_instr(vcpu)) > + goto again; > + else > + exit_code = ARM_EXCEPTION_TRAP; > } > > /* 0 falls through to be handled out of EL2 */ > -- > 2.15.0 > Reviewed-by: Christoffer Dall