On 08/06/2011 01:39 PM, Christoffer Dall wrote:
> Adds a new important function in the main KVM/ARM code called
> handle_exit() which is called from kvm_arch_vcpu_ioctl_run() on returns
> from guest execution. This function examines the Hyp-Syndrome-Register
> (HSR), which contains information telling KVM what caused the exit from
> the guest.
>
> Some of the reasons for an exit are CP15 accesses, which are
> not allowed from the guest and this commits handles these exits by
> emulating the intented operation in software and skip the guest
> instruction.
>
>
> /**
> * kvm_arch_vcpu_ioctl_run - the main VCPU run function to execute guest code
> * @vcpu: The VCPU pointer
> @@ -339,6 +396,26 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *run)
> kvm_guest_exit();
> debug_ws_exit(vcpu->arch.regs.pc);
> trace_kvm_exit(vcpu->arch.regs.pc);
> +
> + ret = handle_exit(vcpu, run, ret);
> + if (ret) {
> + kvm_err(ret, "Error in handle_exit");
> + break;
> + }
> +
> + if (run->exit_reason == KVM_EXIT_MMIO)
> + break;
> +
> + if (need_resched()) {
> + vcpu_put(vcpu);
> + schedule();
> + vcpu_load(vcpu);
> + }
Preempt notifiers mean you don't need vcpu_put()/vcpu_load() - the
scheduler will call kvm_arch_vcpu_put/load() automatically during
context switch.
> +
> + if (signal_pending(current)&& !(run->exit_reason)) {
> + run->exit_reason = KVM_EXIT_IRQ_WINDOW_OPEN;
> + break;
> + }
> }
You're supposed to return -EINTR on a signal. run->exit_reason isn't
defined in this case, but traditionally we return KVM_EXIT_INTR (which
means host signal, not guest signal - yes it's confusing).
> +
> +/**
> + * emulate_cp15_c15_access -- emulates cp15 accesses for CRn == 15
> + * @vcpu: The VCPU pointer
> + * @p: The coprocessor parameters struct pointer holding trap inst. details
> + *
> + * The CP15 c15 register is implementation defined, but some guest kernels
> + * attempt to read/write a diagnostics register here. We always return 0 and
> + * ignore writes and hope for the best. This may need to be refined.
> + */
> +static int emulate_cp15_c15_access(struct kvm_vcpu *vcpu,
> + struct coproc_params *p)
> +{
> + trace_kvm_emulate_cp15_imp(p->Op1, p->Rt1, p->CRn, p->CRm,
> + p->Op2, p->is_write);
_imp?
> +
> + if (!p->is_write)
> + *vcpu_reg(vcpu, p->Rt1) = 0;
> +
> + return 0;
> +}
> +
>
--
error compiling committee.c: too many arguments to function
