From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754649AbdBVLPG (ORCPT ); Wed, 22 Feb 2017 06:15:06 -0500 Received: from mail-wm0-f46.google.com ([74.125.82.46]:37204 "EHLO mail-wm0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753338AbdBVLO7 (ORCPT ); Wed, 22 Feb 2017 06:14:59 -0500 Date: Wed, 22 Feb 2017 12:14:45 +0100 From: Christoffer Dall To: Jintack Lim Cc: christoffer.dall@linaro.org, marc.zyngier@arm.com, pbonzini@redhat.com, rkrcmar@redhat.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will.deacon@arm.com, vladimir.murzin@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.com, james.morse@arm.com, lorenzo.pieralisi@arm.com, kevin.brodsky@arm.com, wcohen@redhat.com, shankerd@codeaurora.org, geoff@infradead.org, andre.przywara@arm.com, eric.auger@redhat.com, anna-maria@linutronix.de, shihwei@cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [RFC 08/55] KVM: arm64: Set virtual EL2 context depending on the guest exception level Message-ID: <20170222111445.GD26976@cbox> References: <1483943091-1364-1-git-send-email-jintack@cs.columbia.edu> <1483943091-1364-9-git-send-email-jintack@cs.columbia.edu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1483943091-1364-9-git-send-email-jintack@cs.columbia.edu> 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 Mon, Jan 09, 2017 at 01:24:04AM -0500, Jintack Lim wrote: > From: Christoffer Dall > > Set up virutal EL2 context to hardware if the guest exception level is > EL2. > > Signed-off-by: Christoffer Dall > Signed-off-by: Jintack Lim > --- > arch/arm64/kvm/context.c | 32 ++++++++++++++++++++++++++------ > 1 file changed, 26 insertions(+), 6 deletions(-) > > diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c > index 320afc6..acb4b1e 100644 > --- a/arch/arm64/kvm/context.c > +++ b/arch/arm64/kvm/context.c > @@ -25,10 +25,25 @@ > void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu) > { > struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt; > + if (unlikely(vcpu_mode_el2(vcpu))) { > + ctxt->hw_pstate = *vcpu_cpsr(vcpu) & ~PSR_MODE_MASK; > > - ctxt->hw_pstate = *vcpu_cpsr(vcpu); > - ctxt->hw_sys_regs = ctxt->sys_regs; > - ctxt->hw_sp_el1 = ctxt->gp_regs.sp_el1; > + /* > + * We emulate virtual EL2 mode in hardware EL1 mode using the > + * same stack pointer mode as the guest expects. > + */ I think this comment should either be deleted or explain why this works as opposed to stating the obvious. How about: /* * We can emulate the guest's configuration of which * stack pointer to use when executing in virtual EL2 by * using the equivalent feature in EL1 to point to * either the EL1 or EL0 stack pointer. */ > + if ((*vcpu_cpsr(vcpu) & PSR_MODE_MASK) == PSR_MODE_EL2h) > + ctxt->hw_pstate |= PSR_MODE_EL1h; > + else > + ctxt->hw_pstate |= PSR_MODE_EL1t; > + > + ctxt->hw_sys_regs = ctxt->shadow_sys_regs; > + ctxt->hw_sp_el1 = ctxt->el2_regs[SP_EL2]; > + } else { > + ctxt->hw_pstate = *vcpu_cpsr(vcpu); > + ctxt->hw_sys_regs = ctxt->sys_regs; > + ctxt->hw_sp_el1 = ctxt->gp_regs.sp_el1; > + } > } > > /** > @@ -38,9 +53,14 @@ void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu) > void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu) > { > struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt; > - > - *vcpu_cpsr(vcpu) = ctxt->hw_pstate; > - ctxt->gp_regs.sp_el1 = ctxt->hw_sp_el1; > + if (unlikely(vcpu_mode_el2(vcpu))) { > + *vcpu_cpsr(vcpu) &= PSR_MODE_MASK; > + *vcpu_cpsr(vcpu) |= ctxt->hw_pstate & ~PSR_MODE_MASK; > + ctxt->el2_regs[SP_EL2] = ctxt->hw_sp_el1; > + } else { > + *vcpu_cpsr(vcpu) = ctxt->hw_pstate; > + ctxt->gp_regs.sp_el1 = ctxt->hw_sp_el1; > + } > } > > void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt) > -- > 1.9.1 > >