MIME-Version: 1.0
In-Reply-To: <20170730195938.GD5176@cbox>
References: <1500397144-16232-1-git-send-email-jintack.lim@linaro.org>
 <1500397144-16232-5-git-send-email-jintack.lim@linaro.org> <20170730195938.GD5176@cbox>
From: Jintack Lim <jintack.lim@linaro.org>
Date: Tue, 1 Aug 2017 09:59:53 -0400
Message-ID: <CAHyh4xhgLxh9qnH0Bi2qpP1hTCmnKiLqz=JZP_9wY46kscigFQ@mail.gmail.com>
Subject: Re: [RFC PATCH v2 04/38] KVM: arm/arm64: Check if nested
 virtualization is in use
To: Christoffer Dall <cdall@linaro.org>
Cc: kvmarm@lists.cs.columbia.edu,
        Christoffer Dall <christoffer.dall@linaro.org>,
        Marc Zyngier <marc.zyngier@arm.com>, Jonathan Corbet <corbet@lwn.net>,
        Paolo Bonzini <pbonzini@redhat.com>,
        =?UTF-8?B?UmFkaW0gS3LEjW3DocWZ?= <rkrcmar@redhat.com>,
        linux@armlinux.org.uk, Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will.deacon@arm.com>, akpm@linux-foundation.org,
        mchehab@kernel.org, cov@codeaurora.org,
        Daniel Lezcano <daniel.lezcano@linaro.org>, david.daney@cavium.com,
        mark.rutland@arm.com, Suzuki K Poulose <suzuki.poulose@arm.com>,
        stefan@hello-penguin.com, Andy Gross <andy.gross@linaro.org>,
        wcohen@redhat.com, Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        shankerd@codeaurora.org, vladimir.murzin@arm.com, james.morse@arm.com,
        linux-doc@vger.kernel.org,
        lkml - Kernel Mailing List <linux-kernel@vger.kernel.org>,
        KVM General <kvm@vger.kernel.org>,
        arm-mail-list <linux-arm-kernel@lists.infradead.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 3102
Lines: 101

On Sun, Jul 30, 2017 at 3:59 PM, Christoffer Dall <cdall@linaro.org> wrote:
> On Tue, Jul 18, 2017 at 11:58:30AM -0500, Jintack Lim wrote:
>> Nested virtualizaion is in use only if all three conditions are met:
>> - The architecture supports nested virtualization.
>> - The kernel parameter is set.
>> - The userspace uses nested virtualiztion feature.
>>
>> Signed-off-by: Jintack Lim <jintack.lim@linaro.org>
>> ---
>>  arch/arm/include/asm/kvm_host.h   | 11 +++++++++++
>>  arch/arm64/include/asm/kvm_host.h |  2 ++
>>  arch/arm64/kvm/nested.c           | 17 +++++++++++++++++
>>  virt/kvm/arm/arm.c                |  4 ++++
>>  4 files changed, 34 insertions(+)
>>
>> diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
>> index 00b0f97..7e9e6c8 100644
>> --- a/arch/arm/include/asm/kvm_host.h
>> +++ b/arch/arm/include/asm/kvm_host.h
>> @@ -303,4 +303,15 @@ static inline int __init kvmarm_nested_cfg(char *buf)
>>  {
>>       return 0;
>>  }
>> +
>> +static inline int init_nested_virt(void)
>> +{
>> +     return 0;
>> +}
>> +
>> +static inline bool nested_virt_in_use(struct kvm_vcpu *vcpu)
>> +{
>> +     return false;
>> +}
>> +
>>  #endif /* __ARM_KVM_HOST_H__ */
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 6df0c7c..86d4b6c 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -387,5 +387,7 @@ static inline void __cpu_init_stage2(void)
>>  }
>>
>>  int __init kvmarm_nested_cfg(char *buf);
>> +int init_nested_virt(void);
>> +bool nested_virt_in_use(struct kvm_vcpu *vcpu);
>>
>>  #endif /* __ARM64_KVM_HOST_H__ */
>> diff --git a/arch/arm64/kvm/nested.c b/arch/arm64/kvm/nested.c
>> index 79f38da..9a05c76 100644
>> --- a/arch/arm64/kvm/nested.c
>> +++ b/arch/arm64/kvm/nested.c
>> @@ -24,3 +24,20 @@ int __init kvmarm_nested_cfg(char *buf)
>>  {
>>       return strtobool(buf, &nested_param);
>>  }
>> +
>> +int init_nested_virt(void)
>> +{
>> +     if (nested_param && cpus_have_const_cap(ARM64_HAS_NESTED_VIRT))
>> +             kvm_info("Nested virtualization is supported\n");
>> +
>> +     return 0;
>> +}
>> +
>> +bool nested_virt_in_use(struct kvm_vcpu *vcpu)
>> +{
>> +     if (nested_param && cpus_have_const_cap(ARM64_HAS_NESTED_VIRT)
>> +         && test_bit(KVM_ARM_VCPU_NESTED_VIRT, vcpu->arch.features))
>> +             return true;
>> +
>> +     return false;
>> +}
>
> after reading through a lot of your patches, I feel like vm_has_el2()
> would be a more elegant name, but it's not a strict requirement to
> change it.

I think it's a nice name. Let me think about it :)

>
>> diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
>> index 1c1c772..36aae3a 100644
>> --- a/virt/kvm/arm/arm.c
>> +++ b/virt/kvm/arm/arm.c
>> @@ -1478,6 +1478,10 @@ int kvm_arch_init(void *opaque)
>>       if (err)
>>               goto out_err;
>>
>> +     err = init_nested_virt();
>> +     if (err)
>> +             return err;
>> +
>>       err = init_subsystems();
>>       if (err)
>>               goto out_hyp;
>> --
>> 1.9.1
>>
>
> Thanks,
> -Christoffer