[Qemu-devel] [PATCH 4/4] arm: vgic device control api support

[Christoffer Dall]

Support creating the ARM vgic device through the device control API and
setting the base address for the distributor and cpu interfaces in KVM
VMs using this API.

Because the older KVM_CREATE_IRQCHIP interface needs the irq chip to be
created prior to creating the VCPUs, we first test if if can use the
device control API in kvm_arch_irqchip_create (using the test flag from
the device control API).  If we cannot, it means we have to fall back to
KVM_CREATE_IRQCHIP and use the older ioctl at this point in time.  If
however, we can use the device control API, we don't do anything and
wait until the arm_gic_kvm driver initializes and let that use the
device control API.

Signed-off-by: Christoffer Dall <address@hidden>
---
 hw/intc/arm_gic_kvm.c |   23 +++++++++++++++++++++--
 target-arm/kvm.c      |   49 ++++++++++++++++++++++++++++++++++++++++++-------
 target-arm/kvm_arm.h  |   18 ++++++++++++------
 3 files changed, 75 insertions(+), 15 deletions(-)

diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
index f713975..9f0a852 100644
--- a/hw/intc/arm_gic_kvm.c
+++ b/hw/intc/arm_gic_kvm.c
@@ -35,6 +35,7 @@ typedef struct KVMARMGICClass {
     ARMGICCommonClass parent_class;
     DeviceRealize parent_realize;
     void (*parent_reset)(DeviceState *dev);
+    int dev_fd;
 } KVMARMGICClass;
 
 static void kvm_arm_gic_set_irq(void *opaque, int irq, int level)
@@ -97,6 +98,7 @@ static void kvm_arm_gic_realize(DeviceState *dev, Error 
**errp)
     GICState *s = KVM_ARM_GIC(dev);
     SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
     KVMARMGICClass *kgc = KVM_ARM_GIC_GET_CLASS(s);
+    int ret;
 
     kgc->parent_realize(dev, errp);
     if (error_is_set(errp)) {
@@ -119,13 +121,27 @@ static void kvm_arm_gic_realize(DeviceState *dev, Error 
**errp)
     for (i = 0; i < s->num_cpu; i++) {
         sysbus_init_irq(sbd, &s->parent_irq[i]);
     }
+
+    /* Try to create the device via the device control API */
+    kgc->dev_fd = -1;
+    ret = kvm_create_device(kvm_state, KVM_DEV_TYPE_ARM_VGIC_V2, false);
+    if (ret >= 0) {
+        kgc->dev_fd = ret;
+    } else if (ret != -ENODEV) {
+        fprintf(stderr, "Error creating in-kernel VGIC: %d\n", ret);
+        abort();
+    }
+
     /* Distributor */
     memory_region_init_reservation(&s->iomem, OBJECT(s),
                                    "kvm-gic_dist", 0x1000);
     sysbus_init_mmio(sbd, &s->iomem);
     kvm_arm_register_device(&s->iomem,
                             (KVM_ARM_DEVICE_VGIC_V2 << KVM_ARM_DEVICE_ID_SHIFT)
-                            | KVM_VGIC_V2_ADDR_TYPE_DIST);
+                            | KVM_VGIC_V2_ADDR_TYPE_DIST,
+                            KVM_DEV_ARM_VGIC_GRP_ADDR,
+                            KVM_VGIC_V2_ADDR_TYPE_DIST,
+                            kgc->dev_fd);
     /* CPU interface for current core. Unlike arm_gic, we don't
      * provide the "interface for core #N" memory regions, because
      * cores with a VGIC don't have those.
@@ -135,7 +151,10 @@ static void kvm_arm_gic_realize(DeviceState *dev, Error 
**errp)
     sysbus_init_mmio(sbd, &s->cpuiomem[0]);
     kvm_arm_register_device(&s->cpuiomem[0],
                             (KVM_ARM_DEVICE_VGIC_V2 << KVM_ARM_DEVICE_ID_SHIFT)
-                            | KVM_VGIC_V2_ADDR_TYPE_CPU);
+                            | KVM_VGIC_V2_ADDR_TYPE_CPU,
+                            KVM_DEV_ARM_VGIC_GRP_ADDR,
+                            KVM_VGIC_V2_ADDR_TYPE_CPU,
+                            kgc->dev_fd);
 }
 
 static void kvm_arm_gic_class_init(ObjectClass *klass, void *data)
diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 2484d90..aed3d86 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c
@@ -184,8 +184,10 @@ out:
  */
 typedef struct KVMDevice {
     struct kvm_arm_device_addr kda;
+    struct kvm_device_attr kdattr;
     MemoryRegion *mr;
     QSLIST_ENTRY(KVMDevice) entries;
+    int dev_fd;
 } KVMDevice;
 
 static QSLIST_HEAD(kvm_devices_head, KVMDevice) kvm_devices_head;
@@ -219,6 +221,28 @@ static MemoryListener devlistener = {
     .region_del = kvm_arm_devlistener_del,
 };
 
+static void kvm_arm_set_device_addr(KVMDevice *kd)
+{
+    struct kvm_device_attr *attr = &kd->kdattr;
+    int ret;
+
+    /* If the device control API is available and we have a device fd on the
+     * KVMDevice struct, let's use the newer API */
+    if (kd->dev_fd >= 0) {
+        uint64_t addr = kd->kda.addr;
+        attr->addr = (uint64_t)(long)&addr;
+        ret = kvm_device_ioctl(kd->dev_fd, KVM_SET_DEVICE_ATTR, attr);
+    } else {
+        ret = kvm_vm_ioctl(kvm_state, KVM_ARM_SET_DEVICE_ADDR, &kd->kda);
+    }
+
+    if (ret < 0) {
+            fprintf(stderr, "Failed to set device address: %s\n",
+                    strerror(errno));
+            abort();
+    }
+}
+
 static void kvm_arm_machine_init_done(Notifier *notifier, void *data)
 {
     KVMDevice *kd, *tkd;
@@ -226,12 +250,7 @@ static void kvm_arm_machine_init_done(Notifier *notifier, 
void *data)
     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_ARM_SET_DEVICE_ADDR,
-                             &kd->kda) < 0) {
-                fprintf(stderr, "KVM_ARM_SET_DEVICE_ADDRESS failed: %s\n",
-                        strerror(errno));
-                abort();
-            }
+            kvm_arm_set_device_addr(kd);
         }
         memory_region_unref(kd->mr);
         g_free(kd);
@@ -242,7 +261,8 @@ static Notifier notify = {
     .notify = kvm_arm_machine_init_done,
 };
 
-void kvm_arm_register_device(MemoryRegion *mr, uint64_t devid)
+void kvm_arm_register_device(MemoryRegion *mr, uint64_t devid, uint64_t group,
+                             uint64_t attr, int dev_fd)
 {
     KVMDevice *kd;
 
@@ -258,6 +278,10 @@ void kvm_arm_register_device(MemoryRegion *mr, uint64_t 
devid)
     kd->mr = mr;
     kd->kda.id = devid;
     kd->kda.addr = -1;
+    kd->kdattr.flags = 0;
+    kd->kdattr.group = group;
+    kd->kdattr.attr = attr;
+    kd->dev_fd = dev_fd;
     QSLIST_INSERT_HEAD(&kvm_devices_head, kd, entries);
     memory_region_ref(kd->mr);
 }
@@ -650,5 +674,16 @@ void kvm_arch_init_irq_routing(KVMState *s)
 
 int kvm_arch_irqchip_create(KVMState *s)
 {
+    int ret;
+
+    /* If we can create the VGIC using the newer device control API, we
+     * let the device do this when it initializes itself, otherwise we
+     * fall back to the old API */
+
+    ret = kvm_create_device(s, KVM_DEV_TYPE_ARM_VGIC_V2, true);
+    if (ret == 0) {
+        return 1;
+    }
+
     return 0;
 }
diff --git a/target-arm/kvm_arm.h b/target-arm/kvm_arm.h
index 5d14887..ea1805a 100644
--- a/target-arm/kvm_arm.h
+++ b/target-arm/kvm_arm.h
@@ -18,16 +18,22 @@
  * kvm_arm_register_device:
  * @mr: memory region for this device
  * @devid: the KVM device ID
+ * @type: device control API device type
+ * @group: device control API group for setting addresses
+ * @attr: device control API address type
+ * @dev_fd: device control device file descriptor (or -1 if not supported)
  *
  * 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.
+ * KVM_ARM_SET_DEVICE_ADDRESS ioctl or the newer device control API.  @devid
+ * should be the ID of the device as defined by KVM_ARM_SET_DEVICE_ADDRESS or
+ * the arm-vgic device in the device control API.
+ * 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, uint64_t devid);
+void kvm_arm_register_device(MemoryRegion *mr, uint64_t devid, uint64_t group,
+                             uint64_t attr, int dev_fd);
 
 /**
  * write_list_to_kvmstate:
-- 
1.7.10.4