[RFC KVM 27/27] kvm/isolation: initialize the KVM page table with KVM buses

[Alexandre Chartre]

KVM buses can change after they have been created so new buses
have to be mapped when they are created.

Signed-off-by: Alexandre Chartre <alexandre.chartre@xxxxxxxxxx>
---
 arch/x86/kvm/isolation.c |   37 +++++++++++++++++++++++++++++++++++++
 arch/x86/kvm/isolation.h |    1 +
 arch/x86/kvm/x86.c       |   13 ++++++++++++-
 include/linux/kvm_host.h |    1 +
 virt/kvm/kvm_main.c      |    2 ++
 5 files changed, 53 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/isolation.c b/arch/x86/kvm/isolation.c
index 255b2da..329e769 100644
--- a/arch/x86/kvm/isolation.c
+++ b/arch/x86/kvm/isolation.c
@@ -1614,6 +1614,29 @@ void kvm_isolation_check_memslots(struct kvm *kvm)
 
 }
 
+void kvm_isolation_check_buses(struct kvm *kvm)
+{
+	struct kvm_range_mapping *rmapping;
+	struct kvm_io_bus *bus;
+	int i, err;
+
+	if (!kvm_isolation())
+		return;
+
+	for (i = 0; i < KVM_NR_BUSES; i++) {
+		bus = kvm->buses[i];
+		rmapping = kvm_get_range_mapping(bus, NULL);
+		if (rmapping)
+			continue;
+		pr_debug("remapping kvm buses[%d]\n", i);
+		err = kvm_copy_ptes(bus, sizeof(*bus) + bus->dev_count *
+		    sizeof(struct kvm_io_range));
+		if (err)
+			pr_debug("failed to map kvm buses[%d]\n", i);
+	}
+
+}
+
 int kvm_isolation_init_vm(struct kvm *kvm)
 {
 	int err, i;
@@ -1632,6 +1655,15 @@ int kvm_isolation_init_vm(struct kvm *kvm)
 			return err;
 	}
 
+	pr_debug("mapping kvm buses\n");
+
+	for (i = 0; i < KVM_NR_BUSES; i++) {
+		err = kvm_copy_ptes(kvm->buses[i],
+		    sizeof(struct kvm_io_bus));
+		if (err)
+			return err;
+	}
+
 	pr_debug("mapping kvm srcu sda\n");
 
 	return (kvm_copy_percpu_mapping(kvm->srcu.sda,
@@ -1650,6 +1682,11 @@ void kvm_isolation_destroy_vm(struct kvm *kvm)
 	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
 		kvm_clear_range_mapping(kvm->memslots[i]);
 
+	pr_debug("unmapping kvm buses\n");
+
+	for (i = 0; i < KVM_NR_BUSES; i++)
+		kvm_clear_range_mapping(kvm->buses[i]);
+
 	pr_debug("unmapping kvm srcu sda\n");
 
 	kvm_clear_percpu_mapping(kvm->srcu.sda);
diff --git a/arch/x86/kvm/isolation.h b/arch/x86/kvm/isolation.h
index 1e55799..b048946 100644
--- a/arch/x86/kvm/isolation.h
+++ b/arch/x86/kvm/isolation.h
@@ -33,6 +33,7 @@ static inline bool kvm_isolation(void)
 extern int kvm_copy_percpu_mapping(void *percpu_ptr, size_t size);
 extern void kvm_clear_percpu_mapping(void *percpu_ptr);
 extern void kvm_isolation_check_memslots(struct kvm *kvm);
+extern void kvm_isolation_check_buses(struct kvm *kvm);
 extern int kvm_add_task_mapping(struct task_struct *tsk);
 extern void kvm_cleanup_task_mapping(struct task_struct *tsk);
 
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 7d98e9f..3ba1996 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9253,6 +9253,13 @@ void kvm_arch_sync_events(struct kvm *kvm)
 	cancel_delayed_work_sync(&kvm->arch.kvmclock_sync_work);
 	cancel_delayed_work_sync(&kvm->arch.kvmclock_update_work);
 	kvm_free_pit(kvm);
+	/*
+	 * Note that kvm_isolation_destroy_vm() has to be called from
+	 * here, and not from kvm_arch_destroy_vm() because it will unmap
+	 * buses which are already destroyed when kvm_arch_destroy_vm()
+	 * is invoked.
+	 */
+	kvm_isolation_destroy_vm(kvm);
 }
 
 int __x86_set_memory_region(struct kvm *kvm, int id, gpa_t gpa, u32 size)
@@ -9331,7 +9338,6 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
 		x86_set_memory_region(kvm, IDENTITY_PAGETABLE_PRIVATE_MEMSLOT, 0, 0);
 		x86_set_memory_region(kvm, TSS_PRIVATE_MEMSLOT, 0, 0);
 	}
-	kvm_isolation_destroy_vm(kvm);
 	if (kvm_x86_ops->vm_destroy)
 		kvm_x86_ops->vm_destroy(kvm);
 	kvm_pic_destroy(kvm);
@@ -9909,6 +9915,11 @@ bool kvm_vector_hashing_enabled(void)
 }
 EXPORT_SYMBOL_GPL(kvm_vector_hashing_enabled);
 
+void kvm_arch_buses_updated(struct kvm *kvm, struct kvm_io_bus *bus)
+{
+	kvm_isolation_check_buses(kvm);
+}
+
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
 EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index ad24d9e..1291d8d 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -199,6 +199,7 @@ void 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);
+void kvm_arch_buses_updated(struct kvm *kvm, struct kvm_io_bus *bus);
 
 #ifdef CONFIG_KVM_ASYNC_PF
 struct kvm_async_pf {
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 3c0c3db..374e79f 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3749,6 +3749,8 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr,
 	synchronize_srcu_expedited(&kvm->srcu);
 	kfree(bus);
 
+	kvm_arch_buses_updated(kvm, new_bus);
+
 	return 0;
 }
 
-- 
1.7.1