On 20/03/2019 13:37, Julien Thierry wrote: > Hi Amit, > > On 19/03/2019 08:30, Amit Daniel Kachhap wrote: >> This adds sections for KVM API extension for pointer authentication. >> A brief description about usage of pointer authentication for KVM guests >> is added in the arm64 documentations.
[...] >> diff --git a/Documentation/virtual/kvm/api.txt >> b/Documentation/virtual/kvm/api.txt >> index 7de9eee..b5c66bc 100644 >> --- a/Documentation/virtual/kvm/api.txt >> +++ b/Documentation/virtual/kvm/api.txt >> @@ -2659,6 +2659,12 @@ Possible features: >> Depends on KVM_CAP_ARM_PSCI_0_2. >> - KVM_ARM_VCPU_PMU_V3: Emulate PMUv3 for the CPU. >> Depends on KVM_CAP_ARM_PMU_V3. >> + - KVM_ARM_VCPU_PTRAUTH_ADDRESS: >> + - KVM_ARM_VCPU_PTRAUTH_GENERIC: >> + Enables Pointer authentication for the CPU. >> + Depends on KVM_CAP_ARM_PTRAUTH and only on arm64 architecture. If >> + set, then the KVM guest allows the execution of pointer authentication >> + instructions. Otherwise, KVM treats these instructions as undefined. >> > > Overall I feel one could easily get confused to whether > PTRAUTH_ADDRESS/GENERIC are two individual features, whether one is a > superset of the other, if the names are just an alias of one another, etc... > > I think the doc should at least stress out that *both* flags are > required to enable ptrauth in a guest. However it raises the question, > if we don't plan to support the features individually (because we > can't), should we really expose two feature flags? I seems odd to > introduce two flags that only do something if used together... Why can't we support the features individually? For example, if we ever get a system where all CPUs support address authentication and none of them support generic authentication, then we could still support address authentication in the guest. Thanks, Kristina _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
