[Qemu-devel] [PATCH v6 4/4] arm: vgic device control api support

[Christoffer Dall <christoffer.dall@linaro.org>]

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 we 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 <christoffer.dall@linaro.org>
---
Changelog[v3 -> v4]:
 - Support creating the gic-kvm with kernels that do not even support
   the device control API, by checking for -ENOTSUP returns from
   kvm_create_device().

Changelog[v2 -> v3]:
 - Fixed indentation
 - Fixed number of parameters in kvm_arm_register_device documentation

Changelog[v1 -> v2]:
 - Moved dev_fd into GICState
 - Proper error handling in kvm_arm_gic_realize
 - Coding style and other minor fixes

 hw/intc/arm_gic_kvm.c            | 22 ++++++++++++++--
 include/hw/intc/arm_gic_common.h |  1 +
 target-arm/kvm.c                 | 55 +++++++++++++++++++++++++++++++++++-----
 target-arm/kvm_arm.h             | 17 ++++++++-----
 4 files changed, 80 insertions(+), 15 deletions(-)

diff --git a/hw/intc/arm_gic_kvm.c b/hw/intc/arm_gic_kvm.c
index 59a3da5..964d4d7 100644
--- a/hw/intc/arm_gic_kvm.c
+++ b/hw/intc/arm_gic_kvm.c
@@ -97,6 +97,7 @@ 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 +120,27 @@ 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 */
+    s->dev_fd = -1;
+    ret = kvm_create_device(kvm_state, KVM_DEV_TYPE_ARM_VGIC_V2, false);
+    if (ret >= 0) {
+        s->dev_fd = ret;
+    } else if (ret != -ENODEV && ret != -ENOTSUP) {
+        error_setg_errno(errp, -ret, "error creating in-kernel VGIC");
+        return;
+    }
+
     /* 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,
+                            s->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 +150,10 @@ 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,
+                            s->dev_fd);
 }
 
 static void kvm_arm_gic_class_init(ObjectClass *klass, void *data)
diff --git a/include/hw/intc/arm_gic_common.h b/include/hw/intc/arm_gic_common.h
index 89384c2..f6887ed 100644
--- a/include/hw/intc/arm_gic_common.h
+++ b/include/hw/intc/arm_gic_common.h
@@ -104,6 +104,7 @@ typedef struct GICState {
     MemoryRegion cpuiomem[GIC_NCPU + 1]; /* CPU interfaces */
     uint32_t num_irq;
     uint32_t revision;
+    int dev_fd; /* kvm device fd if backed by kvm vgic support */
 } GICState;
 
 #define TYPE_ARM_GIC_COMMON "arm_gic_common"
diff --git a/target-arm/kvm.c b/target-arm/kvm.c
index 1d2688d..39202d7 100644
--- a/target-arm/kvm.c
+++ b/target-arm/kvm.c
@@ -165,8 +165,10 @@ unsigned long kvm_arch_vcpu_id(CPUState *cpu)
  */
 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;
@@ -200,6 +202,29 @@ 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 = (uintptr_t)&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(-ret));
+        abort();
+    }
+}
+
 static void kvm_arm_machine_init_done(Notifier *notifier, void *data)
 {
     KVMDevice *kd, *tkd;
@@ -207,12 +232,7 @@ 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);
@@ -223,7 +243,8 @@ 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;
 
@@ -239,6 +260,10 @@ 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);
 }
@@ -389,3 +414,19 @@ void kvm_arch_remove_all_hw_breakpoints(void)
 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 cd3d13c..137c567 100644
--- a/target-arm/kvm_arm.h
+++ b/target-arm/kvm_arm.h
@@ -18,16 +18,21 @@
  * kvm_arm_register_device:
  * @mr: memory region for this device
  * @devid: the KVM device ID
+ * @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:
-- 
1.8.5.2