On 02/03/2017 16:17, Brijesh Singh wrote:
> ASID management:
> - Reserve asid range for SEV guest, SEV asid range is obtained through
> CPUID Fn8000_001f[ECX]. A non-SEV guest can use any asid outside the SEV
> asid range.
How is backwards compatibility handled?
> - SEV guest must have asid value within asid range obtained through CPUID.
> - SEV guest must have the same asid for all vcpu's. A TLB flush is required
> if different vcpu for the same ASID is to be run on the same host CPU.
[...]
> +
> + /* which host cpu was used for running this vcpu */
> + bool last_cpuid;
Should be unsigned int.
>
> + /* Assign the asid allocated for this SEV guest */
> + svm->vmcb->control.asid = asid;
> +
> + /* Flush guest TLB:
> + * - when different VMCB for the same ASID is to be run on the
> + * same host CPU
> + * or
> + * - this VMCB was executed on different host cpu in previous VMRUNs.
> + */
> + if (sd->sev_vmcbs[asid] != (void *)svm->vmcb ||
Why the cast?
> + svm->last_cpuid != cpu)
> + svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ALL_ASID;
If there is a match, you don't need to do anything else (neither reset
the asid, nor mark it as dirty, nor update the fields), so:
if (sd->sev_vmcbs[asid] == svm->vmcb &&
svm->last_cpuid == cpu)
return;
svm->last_cpuid = cpu;
sd->sev_vmcbs[asid] = svm->vmcb;
svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ALL_ASID;
svm->vmcb->control.asid = asid;
mark_dirty(svm->vmcb, VMCB_ASID);
(plus comments ;)).
Also, why not TLB_CONTROL_FLUSH_ASID if possible?
> + svm->last_cpuid = cpu;
> + sd->sev_vmcbs[asid] = (void *)svm->vmcb;
> +
> + mark_dirty(svm->vmcb, VMCB_ASID);
[...]
>
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index fef7d83..9df37a2 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1284,6 +1284,104 @@ struct kvm_s390_ucas_mapping {
> /* Memory Encryption Commands */
> #define KVM_MEMORY_ENCRYPT_OP _IOWR(KVMIO, 0xb8, unsigned long)
>
> +/* Secure Encrypted Virtualization mode */
> +enum sev_cmd_id {
Please add documentation in Documentation/virtual/kvm/memory_encrypt.txt.
Paolo
