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SubjectRe: [PATCH v10 4/5] KVM: arm64: Add capability to advertise ptrauth for guest
On Tue, Apr 23, 2019 at 10:12:37AM +0530, Amit Daniel Kachhap wrote:
> This patch advertises the capability of two cpu feature called address
> pointer authentication and generic pointer authentication. These
> capabilities depend upon system support for pointer authentication and
> VHE mode.
>
> The current arm64 KVM partially implements pointer authentication and
> support of address/generic authentication are tied together. However,
> separate ABI requirements for both of them is added so that any future
> isolated implementation will not require any ABI changes.
>
> 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:
> * Fixed tab alignment issues [Dave Martin].
> * Clarify the api documentation [Dave Martin].
>
> Documentation/virtual/kvm/api.txt | 14 ++++++++++----
> arch/arm64/kvm/reset.c | 5 +++++
> include/uapi/linux/kvm.h | 2 ++
> 3 files changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
> index 32afe7f..fac1887 100644
> --- a/Documentation/virtual/kvm/api.txt
> +++ b/Documentation/virtual/kvm/api.txt
> @@ -2763,13 +2763,19 @@ Possible features:
>
> - KVM_ARM_VCPU_PTRAUTH_ADDRESS: Enables Address Pointer authentication
> for arm64 only.
> - Both KVM_ARM_VCPU_PTRAUTH_ADDRESS and KVM_ARM_VCPU_PTRAUTH_GENERIC
> - must be requested or neither must be requested.
> + Depends on KVM_CAP_ARM_PTRAUTH_ADDRESS.
> + If KVM_CAP_ARM_PTRAUTH_ADDRESS and KVM_CAP_ARM_PTRAUTH_GENERIC are
> + both present, then both KVM_ARM_VCPU_PTRAUTH_ADDRESS and
> + KVM_ARM_VCPU_PTRAUTH_GENERIC must be requested or neither must be
> + requested.
>
> - KVM_ARM_VCPU_PTRAUTH_GENERIC: Enables Generic Pointer authentication
> for arm64 only.
> - Both KVM_ARM_VCPU_PTRAUTH_ADDRESS and KVM_ARM_VCPU_PTRAUTH_GENERIC
> - must be requested or neither must be requested.
> + Depends on KVM_CAP_ARM_PTRAUTH_GENERIC.
> + If KVM_CAP_ARM_PTRAUTH_ADDRESS and KVM_CAP_ARM_PTRAUTH_GENERIC are
> + both present, then both KVM_ARM_VCPU_PTRAUTH_ADDRESS and
> + KVM_ARM_VCPU_PTRAUTH_GENERIC must be requested or neither must be
> + requested.

This looks clear now.

The description is quite heavyweight, but should be hard for people to
misunderstand.

> - KVM_ARM_VCPU_SVE: Enables SVE for the CPU (arm64 only).
> Depends on KVM_CAP_ARM_SVE.
> diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c
> index 028d0c6..f0faf54 100644
> --- a/arch/arm64/kvm/reset.c
> +++ b/arch/arm64/kvm/reset.c
> @@ -101,6 +101,11 @@ int kvm_arch_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_ARM_SVE:
> r = system_supports_sve();
> break;
> + case KVM_CAP_ARM_PTRAUTH_ADDRESS:
> + case KVM_CAP_ARM_PTRAUTH_GENERIC:
> + 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 1d56444..4dc34f8 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -989,6 +989,8 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166
> #define KVM_CAP_HYPERV_CPUID 167
> #define KVM_CAP_ARM_SVE 168
> +#define KVM_CAP_ARM_PTRAUTH_ADDRESS 169
> +#define KVM_CAP_ARM_PTRAUTH_GENERIC 170

[...]

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

Cheers
---Dave

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