[Qemu-devel] [RFC v3 6/8] target-arm: Use MemoryListener to identify GIC base address for KVM

[Peter Maydell <peter.maydell@linaro.org>]

When using an in-kernel GIC with KVM, we need to tell the kernel where
the GIC's memory mapped registers live. Do this by registering a
MemoryListener which tracks where the board model maps the A15's
private peripherals, so we can finish the GIC initialisation
when the GIC is actually mapped.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 target-arm/kvm.c     |   83 ++++++++++++++++++++++++++++++++++++++++++++++++++
 target-arm/kvm_arm.h |   32 +++++++++++++++++++
 2 files changed, 115 insertions(+)
 create mode 100644 target-arm/kvm_arm.h

diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index f7d2235..955983d 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c
@@ -19,6 +19,7 @@
 #include "qemu-timer.h"
 #include "sysemu.h"
 #include "kvm.h"
+#include "kvm_arm.h"
 #include "cpu.h"
 #include "hw/arm-misc.h"
 
@@ -62,6 +63,88 @@ int kvm_arch_init_vcpu(CPUARMState *env)
     return ret;
 }
 
+/* We track all the KVM devices which need their memory addresses
+ * passing to the kernel in a list of these structures.
+ * When board init is complete we run through the list and
+ * tell the kernel the base addresses of the memory regions.
+ * We use a MemoryListener to track mapping and unmapping of
+ * the regions during board creation, so the board models don't
+ * need to do anything special for the KVM case.
+ */
+typedef struct KVMDevice {
+    struct kvm_device_address kda;
+    MemoryRegion *mr;
+    QSLIST_ENTRY(KVMDevice) entries;
+} KVMDevice;
+
+static QSLIST_HEAD(kvm_devices_head, KVMDevice) kvm_devices_head;
+
+static void kvm_arm_devlistener_add(MemoryListener *listener,
+                                    MemoryRegionSection *section)
+{
+    KVMDevice *kd;
+    QSLIST_FOREACH(kd, &kvm_devices_head, entries) {
+        if (section->mr == kd->mr) {
+            kd->kda.addr = section->offset_within_address_space;
+        }
+    }
+}
+
+static void kvm_arm_devlistener_del(MemoryListener *listener,
+                                    MemoryRegionSection *section)
+{
+    KVMDevice *kd;
+    QSLIST_FOREACH(kd, &kvm_devices_head, entries) {
+        if (section->mr == kd->mr) {
+            kd->kda.addr = -1;
+        }
+    }
+}
+
+static MemoryListener devlistener = {
+    .region_add = kvm_arm_devlistener_add,
+    .region_del = kvm_arm_devlistener_del,
+};
+
+static void kvm_arm_machine_init_done(Notifier *notifier, void *data)
+{
+    KVMDevice *kd, *tkd;
+    memory_listener_unregister(&devlistener);
+    QSLIST_FOREACH_SAFE(kd, &kvm_devices_head, entries, tkd) {
+        if (kd->kda.addr != -1) {
+            if (kvm_vm_ioctl(kvm_state, KVM_SET_DEVICE_ADDRESS, &kd->kda) < 0) {
+                fprintf(stderr, "KVM_SET_DEVICE_ADDRESS failed: %s\n",
+                        strerror(errno));
+                abort();
+            }
+        }
+        g_free(kd);
+    }
+}
+
+static Notifier notify = {
+    .notify = kvm_arm_machine_init_done,
+};
+
+void kvm_arm_register_device(MemoryRegion *mr, uint32_t devid)
+{
+    KVMDevice *kd;
+
+    if (!kvm_irqchip_in_kernel()) {
+        return;
+    }
+
+    if (QSLIST_EMPTY(&kvm_devices_head)) {
+        memory_listener_register(&devlistener, NULL);
+        qemu_add_machine_init_done_notifier(&notify);
+    }
+    kd = g_new0(KVMDevice, 1);
+    kd->mr = mr;
+    kd->kda.id = devid;
+    kd->kda.addr = -1;
+    QSLIST_INSERT_HEAD(&kvm_devices_head, kd, entries);
+}
+
 typedef struct Reg {
     uint64_t id;
     int offset;
diff --git a/target-arm/kvm_arm.h b/target-arm/kvm_arm.h
new file mode 100644
index 0000000..93babb2
--- /dev/null
+++ b/target-arm/kvm_arm.h
@@ -0,0 +1,32 @@
+/*
+ * QEMU KVM support -- ARM specific functions.
+ *
+ * Copyright (c) 2012 Linaro Limited
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ *
+ */
+
+#ifndef QEMU_KVM_ARM_H
+#define QEMU_KVM_ARM_H
+
+#include "kvm.h"
+#include "memory.h"
+
+/**
+ * kvm_arm_register_device:
+ * @mr: memory region for this device
+ * @devid: the KVM device ID
+ *
+ * Remember the memory region @mr, and when it is mapped by the
+ * machine model, tell the kernel that base address using the
+ * KVM_SET_DEVICE_ADDRESS ioctl. @devid should be the ID of
+ * the device as defined by KVM_SET_DEVICE_ADDRESS.
+ * The machine model may map and unmap the device multiple times;
+ * the kernel will only be told the final address at the point
+ * where machine init is complete.
+ */
+void kvm_arm_register_device(MemoryRegion *mr, uint32_t devid);
+
+#endif
-- 
1.7.9.5