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
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