KVM: kvm_io_bus: Add kvm_io_bus_get_dev() call

The kvm_io_bus framework is a nice place of holding information about
various MMIO regions for kernel emulated devices.
Add a call to retrieve the kvm_io_device structure which is associated
with a certain MMIO address. This avoids to duplicate kvm_io_bus'
knowledge of MMIO regions without having to fake MMIO calls if a user
needs the device a certain MMIO address belongs to.
This will be used by the ITS emulation to get the associated ITS device
when someone triggers an MSI via an ioctl from userspace.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Acked-by: Christoffer Dall <christoffer.dall@linaro.org>
Acked-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 0640ee92b978721b0bac9b04f961dabc1615077f..614a98137c5f73c09c4f4d6b8edfaf3191467c7f 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -164,6 +164,8 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
                            int len, struct kvm_io_device *dev);
 int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
                              struct kvm_io_device *dev);
+struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+                                        gpa_t addr);
 
 #ifdef CONFIG_KVM_ASYNC_PF
 struct kvm_async_pf {

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index ef54b4c317926248b024c511f61dab7b5124510f..bd2eb92c5d0eb3800c9fb5f7aa437d4a89a70672 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3496,6 +3496,30 @@ int kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx,
        return r;
 }
 
+struct kvm_io_device *kvm_io_bus_get_dev(struct kvm *kvm, enum kvm_bus bus_idx,
+                                        gpa_t addr)
+{
+       struct kvm_io_bus *bus;
+       int dev_idx, srcu_idx;
+       struct kvm_io_device *iodev = NULL;
+
+       srcu_idx = srcu_read_lock(&kvm->srcu);
+
+       bus = srcu_dereference(kvm->buses[bus_idx], &kvm->srcu);
+
+       dev_idx = kvm_io_bus_get_first_dev(bus, addr, 1);
+       if (dev_idx < 0)
+               goto out_unlock;
+
+       iodev = bus->range[dev_idx].dev;
+
+out_unlock:
+       srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+       return iodev;
+}
+EXPORT_SYMBOL_GPL(kvm_io_bus_get_dev);
+
 static struct notifier_block kvm_cpu_notifier = {
        .notifier_call = kvm_cpu_hotplug,
 };