On Thu, Feb 20, 2020 at 05:28:21AM +0000, Ashish Kalra wrote: > On Wed, Feb 19, 2020 at 06:39:39PM -0800, Steve Rutherford wrote: > > On Wed, Feb 12, 2020 at 5:17 PM Ashish Kalra <Ashish.Kalra@xxxxxxx> wrote: > > > > > > static void vmx_cleanup_l1d_flush(void) > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > > index fbabb2f06273..298627fa3d39 100644 > > > --- a/arch/x86/kvm/x86.c > > > +++ b/arch/x86/kvm/x86.c > > > @@ -7547,6 +7547,12 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu) > > > kvm_sched_yield(vcpu->kvm, a0); > > > ret = 0; > > > break; > > > + case KVM_HC_PAGE_ENC_STATUS: > > > + ret = -KVM_ENOSYS; > > > + if (kvm_x86_ops->page_enc_status_hc) > > > + ret = kvm_x86_ops->page_enc_status_hc(vcpu->kvm, > > > + a0, a1, a2); > > > + break; > > > default: > > > ret = -KVM_ENOSYS; > > > break; > > Add a cap to kvm_vm_ioctl_enable_cap so that the vmm can configure > > whether or not this hypercall is offered. Moving to an enable cap > > would also allow the vmm to pass down the expected size of the c-bit > > tracking buffer, so that you don't need to handle dynamic resizing in > > response to guest hypercall, otherwise KVM will sporadically start > > copying around large buffers when working with large VMs. > > > > Yes, that is something we have been looking at adding. > > But, how will VMM know the expected size of the c-bit tracking buffer ? > > The guest kernel and firmware make the hypercall to mark page encryption > status and depending on the GPA range being marked, the kernel's page > encryption bitmap needs to be dynamically resized as response to the guest > hypercall. > Discussed this with Brijesh, though KVM can provide a hint about the expected (max.) size of the c-bit tracking buffer, but there is still an issue for hotplugged guest memory, hence dynamically sized encryption bitmap is probably the right approach. Thanks, Ashish
