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SubjectRe: [PATCH v10 1/5] KVM: arm64: Add a vcpu flag to control ptrauth for guest
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Hi,

On 4/23/19 9:14 PM, Dave Martin wrote:
> On Tue, Apr 23, 2019 at 10:12:34AM +0530, Amit Daniel Kachhap wrote:
>> A per vcpu flag is added to check if pointer authentication is
>> enabled for the vcpu or not. This flag may be enabled according to
>> the necessary user policies and host capabilities.
>>
>> This patch also adds a helper to check the flag.
>>
>> Reviewed-by: Dave Martin <Dave.Martin@arm.com>
>> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Marc Zyngier <marc.zyngier@arm.com>
>> Cc: Christoffer Dall <christoffer.dall@arm.com>
>> Cc: kvmarm@lists.cs.columbia.edu
>> ---
>> Changes since v9:
>>
>> * Added ptrauth cpufeature static check in vcpu_has_ptrauth [Marc Zyngier].
>>
>> arch/arm64/include/asm/kvm_host.h | 5 +++++
>> 1 file changed, 5 insertions(+)
>>
>> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
>> index 7a096fd..7ccac42 100644
>> --- a/arch/arm64/include/asm/kvm_host.h
>> +++ b/arch/arm64/include/asm/kvm_host.h
>> @@ -355,10 +355,15 @@ struct kvm_vcpu_arch {
>> #define KVM_ARM64_HOST_SVE_ENABLED (1 << 4) /* SVE enabled for EL0 */
>> #define KVM_ARM64_GUEST_HAS_SVE (1 << 5) /* SVE exposed to guest */
>> #define KVM_ARM64_VCPU_SVE_FINALIZED (1 << 6) /* SVE config completed */
>> +#define KVM_ARM64_GUEST_HAS_PTRAUTH (1 << 7) /* PTRAUTH exposed to guest */
>>
>> #define vcpu_has_sve(vcpu) (system_supports_sve() && \
>> ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_SVE))
>>
>> +#define vcpu_has_ptrauth(vcpu) ((system_supports_address_auth() || \
>> + system_supports_generic_auth()) && \
>
> Come to think of it, should this be
> system_supports_address_auth() _&&_ system_supports_generic_auth()?
I thought about it and kept it this way so that the implementation
limitation is not introduced in this patch but only in a single place in
the 3rd patch where all the documentation and reasoning is present on
doing this way.
>
> It won't make a functional difference today though, since today
> kvm_vcpu_enable_ptrauth() won't set KVM_ARM64_GUEST_HAS_PTRAUTH without
> system_supports_address_auth() and system_supports_generic_auth() both
> true.
>
> With || here, we won't have to change this if supporting the two auth
> types independently in the future though.
Yes right.
>
> Either way, my Reviewed-by stands.
Thanks,
Amit D
>
> Cheers
> ---Dave
>

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