ANDROID: KVM: Add arch function for device assignment

Add arch specific functions to notify KVM about device/group assignment
to KVM.
pKVM would use this to assign devices at once, as this is a requirement
for pVM device passthrough, that all devices have to be donated first
before the VM using them.
That allow the hypervisor to properly reset the device, and prevent
situations where a devices is not fully owned by pVM.

Bug: 357781595
Bug: 348382247
Change-Id: Icedc6b72eff713702361d424c702eb6c395267dd
Signed-off-by: Mostafa Saleh <smostafa@google.com>

drivers/vfio/group.c

@@ -842,9 +842,6 @@ struct iommu_group *vfio_file_iommu_group(struct file *file)
 	struct vfio_group *group = vfio_group_from_file(file);
 	struct iommu_group *iommu_group = NULL;
 
-	if (!IS_ENABLED(CONFIG_SPAPR_TCE_IOMMU))
-		return NULL;
-
 	if (!group)
 		return NULL;
 

include/linux/kvm_host.h

@@ -1634,6 +1634,31 @@ static __always_inline bool kvm_arch_has_assigned_device(struct kvm *kvm)
 }
 #endif
 
+#ifdef __KVM_HAVE_ARCH_ASSIGNED_DEVICE_GROUP
+int kvm_arch_assign_device(struct device *dev);
+int kvm_arch_assign_group(struct iommu_group *group);
+void kvm_arch_reclaim_device(struct device *dev);
+void kvm_arch_reclaim_group(struct iommu_group *group);
+#else
+static inline int kvm_arch_assign_device(struct device *dev)
+{
+	return 0;
+}
+
+static inline int kvm_arch_assign_group(struct iommu_group *group)
+{
+	return 0;
+}
+
+static inline void kvm_arch_reclaim_device(struct device *dev)
+{
+}
+
+static inline void kvm_arch_reclaim_group(struct iommu_group *group)
+{
+}
+#endif
+
 static inline struct rcuwait *kvm_arch_vcpu_get_wait(struct kvm_vcpu *vcpu)
 {
 #ifdef __KVM_HAVE_ARCH_WQP

virt/kvm/vfio.c

@@ -80,7 +80,22 @@ static bool kvm_vfio_file_is_valid(struct file *file)
 	return ret;
 }
 
-#ifdef CONFIG_SPAPR_TCE_IOMMU
+static struct device *kvm_vfio_file_get_device(struct file *file)
+{
+	struct device *(*fn)(struct file *file);
+	struct device *dev;
+
+	fn = symbol_get(vfio_file_get_device);
+	if (!fn)
+		return NULL;
+
+	dev = fn(file);
+
+	symbol_put(vfio_file_get_device);
+
+	return dev;
+}
+
 static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)
 {
 	struct iommu_group *(*fn)(struct file *file);
@@ -97,6 +112,7 @@ static struct iommu_group *kvm_vfio_file_iommu_group(struct file *file)
 	return ret;
 }
 
+#ifdef CONFIG_SPAPR_TCE_IOMMU
 static void kvm_spapr_tce_release_vfio_group(struct kvm *kvm,
 					     struct kvm_vfio_file *kvf)
 {
@@ -140,6 +156,36 @@ static void kvm_vfio_update_coherency(struct kvm_device *dev)
 	}
 }
 
+static int kvm_vfio_assign_file(struct file *file)
+{
+	struct device *dev;
+	struct iommu_group *group;
+
+	dev = kvm_vfio_file_get_device(file);
+	if (dev)
+		return kvm_arch_assign_device(dev);
+	group = kvm_vfio_file_iommu_group(file);
+	if (group)
+		return kvm_arch_assign_group(group);
+
+	return -ENODEV;
+}
+
+static void kvm_vfio_reclaim_file(struct file *file)
+{
+	struct device *dev;
+	struct iommu_group *group;
+
+	dev = kvm_vfio_file_get_device(file);
+	if (dev) {
+		kvm_arch_reclaim_device(dev);
+		return;
+	}
+	group = kvm_vfio_file_iommu_group(file);
+	if (group)
+		kvm_arch_reclaim_group(group);
+}
+
 static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
 {
 	struct kvm_vfio *kv = dev->private;
@@ -172,6 +218,10 @@ static int kvm_vfio_file_add(struct kvm_device *dev, unsigned int fd)
 		goto out_unlock;
 	}
 
+	ret = kvm_vfio_assign_file(filp);
+	if (ret)
+		goto out_unlock;
+
 	kvf->file = get_file(filp);
 	list_add_tail(&kvf->node, &kv->file_list);
 
@@ -205,6 +255,7 @@ static int kvm_vfio_file_del(struct kvm_device *dev, unsigned int fd)
 		if (kvf->file != fd_file(f))
 			continue;
 
+		kvm_vfio_reclaim_file(kvf->file);
 		list_del(&kvf->node);
 		kvm_arch_end_assignment(dev->kvm);
 #ifdef CONFIG_SPAPR_TCE_IOMMU
@@ -338,6 +389,7 @@ static void kvm_vfio_release(struct kvm_device *dev)
 #ifdef CONFIG_SPAPR_TCE_IOMMU
 		kvm_spapr_tce_release_vfio_group(dev->kvm, kvf);
 #endif
+		kvm_vfio_reclaim_file(kvf->file);
 		kvm_vfio_file_set_kvm(kvf->file, NULL);
 		fput(kvf->file);
 		list_del(&kvf->node);