Messages in this thread | | | Subject | Re: [PATCH v9 1/5] KVM: arm64: Add a vcpu flag to control ptrauth for guest | From | Amit Daniel Kachhap <> | Date | Wed, 17 Apr 2019 18:38:13 +0530 |
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Hi,
On 4/17/19 2:05 PM, Marc Zyngier wrote: > On 12/04/2019 04:20, 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. >> >> 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 v8: >> * Added a new per vcpu flag which will store Pointer Authentication enable >> status instead of checking them again. [Dave Martin] >> >> arch/arm64/include/asm/kvm_host.h | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h >> index 9d57cf8..31dbc7c 100644 >> --- a/arch/arm64/include/asm/kvm_host.h >> +++ b/arch/arm64/include/asm/kvm_host.h >> @@ -355,10 +355,14 @@ 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) \ >> + ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_PTRAUTH) >> + > > Just as for SVE, please first check that the system has PTRAUTH. > Something like: > > (cpus_have_const_cap(ARM64_HAS_GENERIC_AUTH_ARCH) && \ > ((vcpu)->arch.flags & KVM_ARM64_GUEST_HAS_PTRAUTH))
In the subsequent patches, vcpu->arch.flags is only set to KVM_ARM64_GUEST_HAS_PTRAUTH when all host capability check conditions matches such as system_supports_address_auth(), system_supports_generic_auth() so doing them again is repetitive in my view.
Thanks, Amit D
> > This will save an extra load on unsuspecting CPUs thanks to the static > key embedded in the capability structure. > > Thanks, > > M. >
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