On Thu, Oct 12, 2017 at 12:41:16PM +0200, Christoffer Dall wrote:
> The current world-switch function has functionality to detect a number
> of cases where we need to fixup some part of the exit condition and
> possibly run the guest again, before having restored the host state.
>
> This includes populating missing fault info, emulating GICv2 CPU
> interface accesses when mapped at unaligned addresses, and emulating
> the GICv3 CPU interfaceon systems that need that.
interface on
need it.
>
> As we are about to have an alternative switch function for VHE systems,
> but VHE systems still need the same early fixup logic, factor out this
> logic into a separate function that can be shared by both switch
> functions.
>
> No functional change.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxxxxx>
> ---
> arch/arm64/kvm/hyp/switch.c | 91 ++++++++++++++++++++++++++-------------------
> 1 file changed, 52 insertions(+), 39 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c
> index e270cba..ed30af5 100644
> --- a/arch/arm64/kvm/hyp/switch.c
> +++ b/arch/arm64/kvm/hyp/switch.c
> @@ -258,50 +258,24 @@ static void __hyp_text __skip_instr(struct kvm_vcpu *vcpu)
> write_sysreg_el2(*vcpu_pc(vcpu), elr);
> }
>
> -int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
> +/*
> + * Return true when we were able to fixup the guest exit and should return to
> + * the guest, false when we should restore the host state and return to the
> + * main run loop.
> + */
> +static bool __hyp_text fixup_guest_exit(struct kvm_vcpu *vcpu, u64 *exit_code)
> {
> - struct kvm_cpu_context *host_ctxt;
> - struct kvm_cpu_context *guest_ctxt;
> - u64 exit_code;
> -
> - vcpu = kern_hyp_va(vcpu);
> -
> - host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
> - host_ctxt->__hyp_running_vcpu = vcpu;
> - guest_ctxt = &vcpu->arch.ctxt;
> -
> - __sysreg_save_host_state(host_ctxt);
> -
> - __activate_traps(vcpu);
> - __activate_vm(vcpu);
> -
> - __vgic_restore_state(vcpu);
> - __timer_enable_traps(vcpu);
> -
> - /*
> - * We must restore the 32-bit state before the sysregs, thanks
> - * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
> - */
> - __sysreg32_restore_state(vcpu);
> - __sysreg_restore_guest_state(guest_ctxt);
> - __debug_switch_to_guest(vcpu);
> -
> - /* Jump in the fire! */
> -again:
> - exit_code = __guest_enter(vcpu, host_ctxt);
> - /* And we're baaack! */
> -
> /*
> * We're using the raw exception code in order to only process
> * the trap if no SError is pending. We will come back to the
> * same PC once the SError has been injected, and replay the
> * trapping instruction.
> */
> - if (exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))
> - goto again;
> + if (*exit_code == ARM_EXCEPTION_TRAP && !__populate_fault_info(vcpu))
> + return true;
>
> if (static_branch_unlikely(&vgic_v2_cpuif_trap) &&
> - exit_code == ARM_EXCEPTION_TRAP) {
> + *exit_code == ARM_EXCEPTION_TRAP) {
> bool valid;
>
> valid = kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_DABT_LOW &&
> @@ -315,13 +289,13 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
>
> if (ret == 1) {
> __skip_instr(vcpu);
> - goto again;
> + return true;
> }
>
> if (ret == -1) {
> /* Promote an illegal access to an SError */
> __skip_instr(vcpu);
> - exit_code = ARM_EXCEPTION_EL1_SERROR;
> + *exit_code = ARM_EXCEPTION_EL1_SERROR;
> }
>
> /* 0 falls through to be handler out of EL2 */
> @@ -329,19 +303,58 @@ int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
> }
>
> if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
> - exit_code == ARM_EXCEPTION_TRAP &&
> + *exit_code == ARM_EXCEPTION_TRAP &&
> (kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_SYS64 ||
> kvm_vcpu_trap_get_class(vcpu) == ESR_ELx_EC_CP15_32)) {
> int ret = __vgic_v3_perform_cpuif_access(vcpu);
>
> if (ret == 1) {
> __skip_instr(vcpu);
> - goto again;
> + return true;
> }
>
> /* 0 falls through to be handled out of EL2 */
I'm not sure the "0 falls through..." comments are as easy to understand
now that we only fall through to a 'return false'. Maybe they should be
modified?
> }
>
> + return false;
> +}
> +
> +int __hyp_text __kvm_vcpu_run(struct kvm_vcpu *vcpu)
> +{
> + struct kvm_cpu_context *host_ctxt;
> + struct kvm_cpu_context *guest_ctxt;
> + u64 exit_code;
> +
> + vcpu = kern_hyp_va(vcpu);
> +
> + host_ctxt = kern_hyp_va(vcpu->arch.host_cpu_context);
> + host_ctxt->__hyp_running_vcpu = vcpu;
> + guest_ctxt = &vcpu->arch.ctxt;
> +
> + __sysreg_save_host_state(host_ctxt);
> +
> + __activate_traps(vcpu);
> + __activate_vm(vcpu);
> +
> + __vgic_restore_state(vcpu);
> + __timer_enable_traps(vcpu);
> +
> + /*
> + * We must restore the 32-bit state before the sysregs, thanks
> + * to erratum #852523 (Cortex-A57) or #853709 (Cortex-A72).
> + */
> + __sysreg32_restore_state(vcpu);
> + __sysreg_restore_guest_state(guest_ctxt);
> + __debug_switch_to_guest(vcpu);
> +
> + /* Jump in the fire! */
> +again:
> + exit_code = __guest_enter(vcpu, host_ctxt);
> + /* And we're baaack! */
> +
> + if (fixup_guest_exit(vcpu, &exit_code))
> + goto again;
We can change this goto to a do-while now.
> +
> __sysreg_save_guest_state(guest_ctxt);
> __sysreg32_save_state(vcpu);
> __timer_disable_traps(vcpu);
> --
> 2.9.0
>
Thanks,
drew
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