From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754198AbcCBJIV (ORCPT ); Wed, 2 Mar 2016 04:08:21 -0500 Received: from foss.arm.com ([217.140.101.70]:57298 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754445AbcCBJIG (ORCPT ); Wed, 2 Mar 2016 04:08:06 -0500 Subject: Re: [PATCH v2 8/8] arm64: kvm: Check support for AArch32 for 32bit guests To: Suzuki K Poulose , linux-arm-kernel@lists.infradead.org References: <1456393968-17386-1-git-send-email-suzuki.poulose@arm.com> <1456393968-17386-9-git-send-email-suzuki.poulose@arm.com> Cc: christoffer.dall@linaro.org, will.deacon@arm.com, ynorov@caviumnetworks.com, catalin.marinas@arm.com, mark.rutland@arm.com, linux-kernel@vger.kernel.org, kvmarm@lists.cs.columbia.edu From: Marc Zyngier X-Enigmail-Draft-Status: N1110 Organization: ARM Ltd Message-ID: <56D6AD72.8010108@arm.com> Date: Wed, 2 Mar 2016 09:08:02 +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: <1456393968-17386-9-git-send-email-suzuki.poulose@arm.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 25/02/16 09:52, Suzuki K Poulose wrote: > Add a check to make sure the system supports AArch32 state > before initialising a 32bit guest. > > Cc: Christoffer Dall > Cc: Marc Zyngier > Cc: kvmarm@lists.cs.columbia.edu > Signed-off-by: Suzuki K Poulose > > --- > > I really wanted to pass kvm_vcpu down to the helpers. But then, I can't > define the arch specific helper in asm/kvm_host.h due to lack of kvm_vcpu's > definition yet: > > In file included from include/linux/kvm_host.h:35:0, > from arch/arm64/kernel/asm-offsets.c:24: > ./arch/arm64/include/asm/kvm_host.h: In function ‘kvm_arch_vcpu_validate_features’: > ./arch/arm64/include/asm/kvm_host.h:344:48: error: dereferencing pointer to incomplete type > return !test_bit(KVM_ARM_VCPU_EL1_32BIT, vcpu->arch.features) || Why don't you just have the prototype in kvm_host.h, and move the actual implementation to something like guest.c? But I think there is a better approach, see below. > --- > arch/arm/include/asm/kvm_host.h | 5 +++++ > arch/arm/kvm/arm.c | 3 +++ > arch/arm64/include/asm/kvm_host.h | 8 ++++++++ > 3 files changed, 16 insertions(+) > > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h > index f9f2779..945c23a 100644 > --- a/arch/arm/include/asm/kvm_host.h > +++ b/arch/arm/include/asm/kvm_host.h > @@ -238,6 +238,11 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {} > static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {} > static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} > > +static inline bool kvm_arch_vcpu_validate_features(struct kvm_vcpu_arch *arch_vcpu) > +{ > + return true; > +} > + > 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) {} > diff --git a/arch/arm/kvm/arm.c b/arch/arm/kvm/arm.c > index dda1959..fc4ea37 100644 > --- a/arch/arm/kvm/arm.c > +++ b/arch/arm/kvm/arm.c > @@ -787,6 +787,9 @@ static int kvm_vcpu_set_target(struct kvm_vcpu *vcpu, > set_bit(i, vcpu->arch.features); > } > > + if (!kvm_arch_vcpu_validate_features(&vcpu->arch)) > + return -EINVAL; > + > vcpu->arch.target = phys_target; > > /* Now we know what it is, we can reset it. */ > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h > index 689d4c9..9d60a6c 100644 > --- a/arch/arm64/include/asm/kvm_host.h > +++ b/arch/arm64/include/asm/kvm_host.h > @@ -24,6 +24,8 @@ > > #include > #include > +#include > +#include > #include > #include > > @@ -338,6 +340,12 @@ static inline void kvm_arch_sync_events(struct kvm *kvm) {} > static inline void kvm_arch_vcpu_uninit(struct kvm_vcpu *vcpu) {} > static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {} > > +static inline bool kvm_arch_vcpu_validate_features(struct kvm_vcpu_arch *arch_vcpu) > +{ > + return !test_bit(KVM_ARM_VCPU_EL1_32BIT, arch_vcpu->features) || > + system_supports_32bit_el0(); > +} > + This is really convoluted (it took me 5 minutes staring at the expression and remembering that AArch32 EL1 implies AArch32 EL0 to get it). Now, we already have kvm_reset_vcpu() that validates AArch32 support. It would probably be better to move things there. Thoughts? > void kvm_arm_init_debug(void); > void kvm_arm_setup_debug(struct kvm_vcpu *vcpu); > void kvm_arm_clear_debug(struct kvm_vcpu *vcpu); > Thanks, M. -- Jazz is not dead. It just smells funny...