From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932078AbeDYQKW (ORCPT ); Wed, 25 Apr 2018 12:10:22 -0400 Received: from foss.arm.com ([217.140.101.70]:42266 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755071AbeDYQKR (ORCPT ); Wed, 25 Apr 2018 12:10:17 -0400 Subject: Re: [PATCH v2 13/17] kvm: arm/arm64: Allow tuning the physical address size for VM To: Suzuki K Poulose , linux-arm-kernel@lists.infradead.org Cc: mark.rutland@arm.com, peter.maydell@linaro.org, ard.biesheuvel@linaro.org, cdall@kernel.org, kvm@vger.kernel.org, rkrcmar@redhat.com, marc.zyngier@arm.com, catalin.marinas@arm.com, punit.agrawal@arm.com, will.deacon@arm.com, linux-kernel@vger.kernel.org, kristina.martsenko@arm.com, pbonzini@redhat.com, kvmarm@lists.cs.columbia.edu References: <1522156531-28348-1-git-send-email-suzuki.poulose@arm.com> <1522156531-28348-14-git-send-email-suzuki.poulose@arm.com> From: Julien Grall Message-ID: <81e98b32-8c13-3688-209f-2d51b2237748@arm.com> Date: Wed, 25 Apr 2018 17:10:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.6.0 MIME-Version: 1.0 In-Reply-To: <1522156531-28348-14-git-send-email-suzuki.poulose@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Suzuki, On 27/03/18 14:15, Suzuki K Poulose wrote: > Allow specifying the physical address size for a new VM via > the kvm_type argument for KVM_CREATE_VM ioctl. This allows > us to finalise the stage2 page table format as early as possible > and hence perform the right checks on the memory slots without > complication. The size is encoded as Log2(PA_Siz) in the bits[7:0] s/PA_Siz/PA_Size/. > of the type field and can encode more information in the future if > required. > > Cc: Marc Zyngier > Cc: Christoffer Dall > Cc: Peter Maydel > Cc: Paolo Bonzini > Cc: Radim Krčmář > Signed-off-by: Suzuki K Poulose > --- > arch/arm/include/asm/kvm_mmu.h | 2 ++ > arch/arm64/include/asm/kvm_mmu.h | 2 ++ > include/uapi/linux/kvm.h | 10 ++++++++++ > virt/kvm/arm/arm.c | 24 ++++++++++++++++++++++-- > 4 files changed, 36 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/include/asm/kvm_mmu.h b/arch/arm/include/asm/kvm_mmu.h > index 50896da..3f13827 100644 > --- a/arch/arm/include/asm/kvm_mmu.h > +++ b/arch/arm/include/asm/kvm_mmu.h > @@ -323,6 +323,8 @@ static inline u32 kvm_get_ipa_limit(void) > return KVM_PHYS_SHIFT; > } > > +static inline void kvm_config_stage2(struct kvm *kvm, u32 ipa_shift) {} > + > #endif /* !__ASSEMBLY__ */ > > #endif /* __ARM_KVM_MMU_H__ */ > diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h > index a4c8c00..bb458bf 100644 > --- a/arch/arm64/include/asm/kvm_mmu.h > +++ b/arch/arm64/include/asm/kvm_mmu.h > @@ -416,5 +416,7 @@ static inline u32 kvm_get_ipa_limit(void) > return KVM_PHYS_SHIFT; > } > > +static inline void kvm_config_stage2(struct kvm *kvm, u32 ipa_shift) {} > + > #endif /* __ASSEMBLY__ */ > #endif /* __ARM64_KVM_MMU_H__ */ > diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h > index b737ee1..67b09b0 100644 > --- a/include/uapi/linux/kvm.h > +++ b/include/uapi/linux/kvm.h > @@ -740,6 +740,16 @@ struct kvm_ppc_resize_hpt { > #define KVM_S390_SIE_PAGE_OFFSET 1 > > /* > + * On arm/arm64, machine type can be used to request the physical > + * address size for the VM. Bits [7-0] have been reserved for the > + * PA size shift (i.e, log2(PA-Size)). For backward compatibility, I would s/PA-Size/PA_Size/ to avoid the impression that it is a substraction. > + * value 0 implies the default IPA size, which is 40bits. > + */ > +#define KVM_VM_TYPE_ARM_PHYS_SHIFT_MASK 0xff > +#define KVM_VM_TYPE_ARM_PHYS_SHIFT(x) \ > + ((x) & KVM_VM_TYPE_ARM_PHYS_SHIFT_MASK) > + > +/* > * ioctls for /dev/kvm fds: > */ > #define KVM_GET_API_VERSION _IO(KVMIO, 0x00) > diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c > index 53bb05c..13eb66f 100644 > --- a/virt/kvm/arm/arm.c > +++ b/virt/kvm/arm/arm.c > @@ -110,6 +110,25 @@ void kvm_arch_check_processor_compat(void *rtn) > } > > > +static int kvm_arch_config_vm(struct kvm *kvm, unsigned long type) > +{ > + u32 ipa_shift = (u32)type & KVM_VM_TYPE_ARM_PHYS_SHIFT_MASK; How about using KVM_VM_TYPE_ARM_PHYS_SHIFT(type) directly here? I am not entirely sure whether the cast is necessary. If it is, then I think you want to add it in KVM_VM_TYPE_ARM_PHYS_SHIFT(...) as well. > + > + /* > + * Make sure the size, if specified, is within the range of > + * default size and supported maximum limit. > + */ > + if (ipa_shift) { > + if (ipa_shift < KVM_PHYS_SHIFT || ipa_shift > kvm_ipa_limit) > + return -EINVAL; > + } else { > + ipa_shift = KVM_PHYS_SHIFT; > + } > + > + kvm_config_stage2(kvm, ipa_shift); > + return 0; > +} > + > /** > * kvm_arch_init_vm - initializes a VM data structure > * @kvm: pointer to the KVM struct > @@ -118,8 +137,9 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) > { > int ret, cpu; > > - if (type) > - return -EINVAL; > + ret = kvm_arch_config_vm(kvm, type); > + if (ret) > + return ret; > > kvm->arch.last_vcpu_ran = alloc_percpu(typeof(*kvm->arch.last_vcpu_ran)); > if (!kvm->arch.last_vcpu_ran) > Cheers, -- Julien Grall