On Mon, Aug 26, 2019 at 04:21:00PM +1000, Suraj Jitindar Singh wrote:
> A version 2 of the H_ENTER_NESTED hcall was added with an argument to
> specify the slb entries which should be used to run the nested guest.
>
> Add support for this version of the hcall structures to
> kvmhv_enter_nested_guest() and context switch the slb when the nested
> guest being run is a hpt (hash page table) guest.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
Question below...
> @@ -307,6 +335,26 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
> vcpu->arch.regs.msr = vcpu->arch.shregs.msr;
> saved_l1_regs = vcpu->arch.regs;
> kvmhv_save_hv_regs(vcpu, &saved_l1_hv);
> + /* if running hpt then context switch the slb in the vcpu struct */
> + if (!radix) {
> + slb_ptr = kvmppc_get_gpr(vcpu, 6);
> + l2_slb = kzalloc(sizeof(*l2_slb), GFP_KERNEL);
> + saved_l1_slb = kzalloc(sizeof(*saved_l1_slb), GFP_KERNEL);
> +
> + if ((!l2_slb) || (!saved_l1_slb)) {
> + ret = H_HARDWARE;
> + goto out_free;
> + }
> + err = kvm_vcpu_read_guest(vcpu, slb_ptr, l2_slb,
> + sizeof(struct guest_slb));
> + if (err) {
> + ret = H_PARAMETER;
> + goto out_free;
> + }
> + if (kvmppc_need_byteswap(vcpu))
> + byteswap_guest_slb(l2_slb);
> + kvmhv_save_guest_slb(vcpu, saved_l1_slb);
Why are we bothering to save the SLB state of the L1 guest, which has
to be a radix guest? Won't the L1 SLB state always just have 0
entries?
> @@ -354,6 +409,8 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu)
> vcpu->arch.shregs.msr |= MSR_TS_S;
> vc->tb_offset = saved_l1_hv.tb_offset;
> restore_hv_regs(vcpu, &saved_l1_hv);
> + if (!radix)
> + kvmhv_restore_guest_slb(vcpu, saved_l1_slb);
Likewise here can't we just set vcpu->arch.slb_max and
vcpu->arch.slb_nr to zero?
Paul.
