linux-kernel - Re: [PATCH v7 8/10] KVM: arm64: Add capability to advertise ptrauth for guest

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Date:   Tue, 26 Mar 2019 09:42:01 +0530
From:   Amit Daniel Kachhap <amit.kachhap@....com>
To:     Kristina Martsenko <kristina.martsenko@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Christoffer Dall <christoffer.dall@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Andrew Jones <drjones@...hat.com>,
        Dave Martin <Dave.Martin@....com>,
        Ramana Radhakrishnan <ramana.radhakrishnan@....com>,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry@....com>
Subject: Re: [PATCH v7 8/10] KVM: arm64: Add capability to advertise ptrauth
 for guest

Hi,

On 3/26/19 1:35 AM, Kristina Martsenko wrote:
> On 19/03/2019 08:30, Amit Daniel Kachhap wrote:
>> This patch advertises the capability of pointer authentication
>> when system supports pointer authentication and VHE mode present.
>>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@....com>
>> Cc: Mark Rutland <mark.rutland@....com>
>> Cc: Marc Zyngier <marc.zyngier@....com>
>> Cc: Christoffer Dall <christoffer.dall@....com>
>> Cc: kvmarm@...ts.cs.columbia.edu
>> ---
>>   arch/arm64/kvm/reset.c   | 4 ++++
>>   include/uapi/linux/kvm.h | 1 +
>>   2 files changed, 5 insertions(+)
>>
>> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
>> index 00f0639..a3b269e 100644
>> --- a/arch/arm64/kvm/reset.c
>> +++ b/arch/arm64/kvm/reset.c
>> @@ -92,6 +92,10 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
>>   	case KVM_CAP_ARM_VM_IPA_SIZE:
>>   		r = kvm_ipa_limit;
>>   		break;
>> +	case KVM_CAP_ARM_PTRAUTH:
>> +		r = has_vhe() && system_supports_address_auth() &&
>> +			system_supports_generic_auth();
>> +		break;
>>   	default:
>>   		r = 0;
>>   	}
>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>> index 6d4ea4b..a553477 100644
>> --- a/include/uapi/linux/kvm.h
>> +++ b/include/uapi/linux/kvm.h
>> @@ -988,6 +988,7 @@ struct kvm_ppc_resize_hpt {
>>   #define KVM_CAP_ARM_VM_IPA_SIZE 165
>>   #define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166
>>   #define KVM_CAP_HYPERV_CPUID 167
>> +#define KVM_CAP_ARM_PTRAUTH 168
> 
> Since we now have two separate vcpu flags, then I think we also need two
> capabilities here (one for address auth and one for generic auth). This
> will allow us to support the features separately in the future if we
> need to.
I have no objection to your suggestion. Infact all other KVM_ARM_VCPU_* 
features have there own capability defined. I will check other 
architectures if they define separate capability for major/minor features.

Thanks,
Amit D
> 
> Thanks,
> Kristina
>