On Wed, Oct 09, 2024 at 07:59:50PM +0100, Marc Zyngier wrote:
> +static void __sysreg_restore_vel2_state(struct kvm_vcpu *vcpu)
> +{
> + u64 val;
> +
> + /* These registers are common with EL1 */
> + write_sysreg(__vcpu_sys_reg(vcpu, PAR_EL1), par_el1);
> + write_sysreg(__vcpu_sys_reg(vcpu, TPIDR_EL1), tpidr_el1);
> +
> + write_sysreg(read_cpuid_id(), vpidr_el2);
I don't think we need to restore VPIDR_EL2 here, so long as we do it on
vcpu_put() when leaving a nested VM context. That seems like the right
place to have it, as we could be running a mix of nested and non-nested
VMs and don't ever poke VPIDR_EL2 for non-NV VMs.
> @@ -89,7 +192,29 @@ void __vcpu_load_switch_sysregs(struct kvm_vcpu *vcpu)
> */
> __sysreg32_restore_state(vcpu);
> __sysreg_restore_user_state(guest_ctxt);
> - __sysreg_restore_el1_state(guest_ctxt);
> +
> + if (unlikely(__is_hyp_ctxt(guest_ctxt))) {
> + __sysreg_restore_vel2_state(vcpu);
> + } else {
> + if (vcpu_has_nv(vcpu)) {
> + /*
> + * Only set VPIDR_EL2 for nested VMs, as this is the
> + * only time it changes. We'll restore the MIDR_EL1
> + * view on put.
> + */
Slightly ambiguous what "VPIDR_EL2" this is referring to (hardware reg
v. guest value). Maybe:
/*
* Use the guest hypervisor's VPIDR_EL2 when in a nested
* state. The hardware value of MIDR_EL1 gets restored on
* put.
*/
> + write_sysreg(ctxt_sys_reg(guest_ctxt, VPIDR_EL2), vpidr_el2);
> +
> + /*
> + * As we're restoring a nested guest, set the value
> + * provided by the guest hypervisor.
> + */
> + mpidr = ctxt_sys_reg(guest_ctxt, VMPIDR_EL2);
> + } else {
> + mpidr = ctxt_sys_reg(guest_ctxt, MPIDR_EL1);
> + }
> +
> + __sysreg_restore_el1_state(guest_ctxt, mpidr);
> + }
>
> vcpu_set_flag(vcpu, SYSREGS_ON_CPU);
> }
> @@ -112,12 +237,20 @@ void __vcpu_put_switch_sysregs(struct kvm_vcpu *vcpu)
>
> host_ctxt = host_data_ptr(host_ctxt);
>
> - __sysreg_save_el1_state(guest_ctxt);
> + if (unlikely(__is_hyp_ctxt(guest_ctxt)))
> + __sysreg_save_vel2_state(vcpu);
> + else
> + __sysreg_save_el1_state(guest_ctxt);
> +
> __sysreg_save_user_state(guest_ctxt);
> __sysreg32_save_state(vcpu);
>
> /* Restore host user state */
> __sysreg_restore_user_state(host_ctxt);
>
> + /* If leaving a nesting guest, restore MPIDR_EL1 default view */
typo: MIDR_EL1
> + if (vcpu_has_nv(vcpu))
> + write_sysreg(read_cpuid_id(), vpidr_el2);
> +
> vcpu_clear_flag(vcpu, SYSREGS_ON_CPU);
> }
> --
> 2.39.2
>
--
Thanks,
Oliver
