KVM: PPC: booke: expose good state on irq reinject

When reinjecting an interrupt into the host interrupt handler after we're
back in host kernel land, we need to tell the kernel where the interrupt
happened. We can't tell it that we were in guest state, because that might
lead to random code walking host addresses. So instead, we tell it that
we came from the interrupt reinject code.

This helps getting reasonable numbers out of perf.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Avi Kivity <avi@redhat.com>

arch/powerpc/kvm/booke.c

@@ -595,37 +595,63 @@ static int emulation_exit(struct kvm_run *run, struct kvm_vcpu *vcpu)
 	}
 }
 
-/**
- * kvmppc_handle_exit
- *
- * Return value is in the form (errcode<<2 | RESUME_FLAG_HOST | RESUME_FLAG_NV)
- */
-int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
-                       unsigned int exit_nr)
+static void kvmppc_fill_pt_regs(struct pt_regs *regs)
 {
-	int r = RESUME_HOST;
+	ulong r1, ip, msr, lr;
+
+	asm("mr %0, 1" : "=r"(r1));
+	asm("mflr %0" : "=r"(lr));
+	asm("mfmsr %0" : "=r"(msr));
+	asm("bl 1f; 1: mflr %0" : "=r"(ip));
+
+	memset(regs, 0, sizeof(*regs));
+	regs->gpr[1] = r1;
+	regs->nip = ip;
+	regs->msr = msr;
+	regs->link = lr;
+}
 
-	/* update before a new last_exit_type is rewritten */
-	kvmppc_update_timing_stats(vcpu);
+static void kvmppc_restart_interrupt(struct kvm_vcpu *vcpu,
+				     unsigned int exit_nr)
+{
+	struct pt_regs regs;
 
 	switch (exit_nr) {
 	case BOOKE_INTERRUPT_EXTERNAL:
-		do_IRQ(current->thread.regs);
+		kvmppc_fill_pt_regs(&regs);
+		do_IRQ(&regs);
 		break;
-
 	case BOOKE_INTERRUPT_DECREMENTER:
-		timer_interrupt(current->thread.regs);
+		kvmppc_fill_pt_regs(&regs);
+		timer_interrupt(&regs);
 		break;
-
 #if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_BOOK3E_64)
 	case BOOKE_INTERRUPT_DOORBELL:
-		doorbell_exception(current->thread.regs);
+		kvmppc_fill_pt_regs(&regs);
+		doorbell_exception(&regs);
 		break;
 #endif
 	case BOOKE_INTERRUPT_MACHINE_CHECK:
 		/* FIXME */
 		break;
 	}
+}
+
+/**
+ * kvmppc_handle_exit
+ *
+ * Return value is in the form (errcode<<2 | RESUME_FLAG_HOST | RESUME_FLAG_NV)
+ */
+int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
+                       unsigned int exit_nr)
+{
+	int r = RESUME_HOST;
+
+	/* update before a new last_exit_type is rewritten */
+	kvmppc_update_timing_stats(vcpu);
+
+	/* restart interrupts if they were meant for the host */
+	kvmppc_restart_interrupt(vcpu, exit_nr);
 
 	local_irq_enable();