Expose KVM_MEM_PRIVATE and memslot fields private_fd/offset to
userspace. KVM will register/unregister private memslot to fd-based
memory backing store and response to invalidation event from
inaccessible_notifier to zap the existing memory mappings in the
secondary page table.
Whether KVM_MEM_PRIVATE is actually exposed to userspace is determined
by architecture code which can turn on it by overriding the default
kvm_arch_has_private_mem().
A 'kvm' reference is added in memslot structure since in
inaccessible_notifier callback we can only obtain a memslot reference
but 'kvm' is needed to do the zapping.
Co-developed-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Yu Zhang <yu.c.zhang@xxxxxxxxxxxxxxx>
Signed-off-by: Chao Peng <chao.p.peng@xxxxxxxxxxxxxxx>
---
include/linux/kvm_host.h | 1 +
virt/kvm/kvm_main.c | 116 +++++++++++++++++++++++++++++++++++++--
2 files changed, 111 insertions(+), 6 deletions(-)
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b9906cdf468b..cb4eefac709c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -589,6 +589,7 @@ struct kvm_memory_slot {
struct file *private_file;
loff_t private_offset;
struct inaccessible_notifier notifier;
+ struct kvm *kvm;
};
static inline bool kvm_slot_can_be_private(const struct kvm_memory_slot *slot)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 97d893f7482c..87e239d35b96 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -983,6 +983,57 @@ static int kvm_vm_ioctl_set_mem_attr(struct kvm *kvm, gpa_t gpa, gpa_t size,
xa_erase(&kvm->mem_attr_array, index);
return r;
}
+
+static void kvm_private_notifier_invalidate(struct inaccessible_notifier *notifier,
+ pgoff_t start, pgoff_t end)
+{
+ struct kvm_memory_slot *slot = container_of(notifier,
+ struct kvm_memory_slot,
+ notifier);
+ unsigned long base_pgoff = slot->private_offset >> PAGE_SHIFT;
+ gfn_t start_gfn = slot->base_gfn;
+ gfn_t end_gfn = slot->base_gfn + slot->npages;
+
+
+ if (start > base_pgoff)
+ start_gfn = slot->base_gfn + start - base_pgoff;
+
+ if (end < base_pgoff + slot->npages)
+ end_gfn = slot->base_gfn + end - base_pgoff;
+
+ if (start_gfn >= end_gfn)
+ return;
+
+ kvm_zap_gfn_range(slot->kvm, start_gfn, end_gfn);
+}
+
+static struct inaccessible_notifier_ops kvm_private_notifier_ops = {
+ .invalidate = kvm_private_notifier_invalidate,
+};
+
+static inline void kvm_private_mem_register(struct kvm_memory_slot *slot)
+{
+ slot->notifier.ops = &kvm_private_notifier_ops;
+ inaccessible_register_notifier(slot->private_file, &slot->notifier);
+}
+
+static inline void kvm_private_mem_unregister(struct kvm_memory_slot *slot)
+{
+ inaccessible_unregister_notifier(slot->private_file, &slot->notifier);
+}
+
+#else /* !CONFIG_HAVE_KVM_PRIVATE_MEM */
+
+static inline void kvm_private_mem_register(struct kvm_memory_slot *slot)
+{
+ WARN_ON_ONCE(1);
+}
+
+static inline void kvm_private_mem_unregister(struct kvm_memory_slot *slot)
+{
+ WARN_ON_ONCE(1);
+}
+
#endif /* CONFIG_HAVE_KVM_PRIVATE_MEM */
#ifdef CONFIG_HAVE_KVM_PM_NOTIFIER
@@ -1029,6 +1080,11 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot)
/* This does not remove the slot from struct kvm_memslots data structures */
static void kvm_free_memslot(struct kvm *kvm, struct kvm_memory_slot *slot)
{
+ if (slot->flags & KVM_MEM_PRIVATE) {
+ kvm_private_mem_unregister(slot);
+ fput(slot->private_file);
+ }
+
kvm_destroy_dirty_bitmap(slot);
kvm_arch_free_memslot(kvm, slot);
@@ -1600,10 +1656,16 @@ bool __weak kvm_arch_has_private_mem(struct kvm *kvm)
return false;
}
-static int check_memory_region_flags(const struct kvm_user_mem_region *mem)
+static int check_memory_region_flags(struct kvm *kvm,
+ const struct kvm_user_mem_region *mem)
{
u32 valid_flags = KVM_MEM_LOG_DIRTY_PAGES;
+#ifdef CONFIG_HAVE_KVM_PRIVATE_MEM
+ if (kvm_arch_has_private_mem(kvm))
+ valid_flags |= KVM_MEM_PRIVATE;
+#endif
+
#ifdef __KVM_HAVE_READONLY_MEM
valid_flags |= KVM_MEM_READONLY;
#endif
@@ -1679,6 +1741,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm,
{
int r;
+ if (change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE)
+ kvm_private_mem_register(new);
+
/*
* If dirty logging is disabled, nullify the bitmap; the old bitmap
* will be freed on "commit". If logging is enabled in both old and
@@ -1707,6 +1772,9 @@ static int kvm_prepare_memory_region(struct kvm *kvm,
if (r && new && new->dirty_bitmap && (!old || !old->dirty_bitmap))
kvm_destroy_dirty_bitmap(new);
+ if (r && change == KVM_MR_CREATE && new->flags & KVM_MEM_PRIVATE)
+ kvm_private_mem_unregister(new);
+
return r;
}
@@ -2004,7 +2072,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
int as_id, id;
int r;
- r = check_memory_region_flags(mem);
+ r = check_memory_region_flags(kvm, mem);
if (r)
return r;
@@ -2023,6 +2091,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
!access_ok((void __user *)(unsigned long)mem->userspace_addr,
mem->memory_size))
return -EINVAL;
+ if (mem->flags & KVM_MEM_PRIVATE &&
+ (mem->private_offset & (PAGE_SIZE - 1) ||
+ mem->private_offset > U64_MAX - mem->memory_size))
+ return -EINVAL;
if (as_id >= KVM_ADDRESS_SPACE_NUM || id >= KVM_MEM_SLOTS_NUM)
return -EINVAL;
if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
@@ -2061,6 +2133,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
if ((kvm->nr_memslot_pages + npages) < kvm->nr_memslot_pages)
return -EINVAL;
} else { /* Modify an existing slot. */
+ /* Private memslots are immutable, they can only be deleted. */
+ if (mem->flags & KVM_MEM_PRIVATE)
+ return -EINVAL;
if ((mem->userspace_addr != old->userspace_addr) ||
(npages != old->npages) ||
((mem->flags ^ old->flags) & KVM_MEM_READONLY))
@@ -2089,10 +2164,27 @@ int __kvm_set_memory_region(struct kvm *kvm,
new->npages = npages;
new->flags = mem->flags;
new->userspace_addr = mem->userspace_addr;
+ if (mem->flags & KVM_MEM_PRIVATE) {
+ new->private_file = fget(mem->private_fd);
+ if (!new->private_file) {
+ r = -EINVAL;
+ goto out;
+ }
+ new->private_offset = mem->private_offset;
+ }
+
+ new->kvm = kvm;
r = kvm_set_memslot(kvm, old, new, change);
if (r)
- kfree(new);
+ goto out;
+
+ return 0;
+
+out:
+ if (new->private_file)
+ fput(new->private_file);
+ kfree(new);
return r;
}
EXPORT_SYMBOL_GPL(__kvm_set_memory_region);
@@ -4747,16 +4839,28 @@ static long kvm_vm_ioctl(struct file *filp,
}
case KVM_SET_USER_MEMORY_REGION: {
struct kvm_user_mem_region mem;
- unsigned long size = sizeof(struct kvm_userspace_memory_region);
+ unsigned int flags_offset = offsetof(typeof(mem), flags);
+ unsigned long size;
+ u32 flags;
kvm_sanity_check_user_mem_region_alias();
+ memset(&mem, 0, sizeof(mem));
+
r = -EFAULT;
- if (copy_from_user(&mem, argp, size);
+ if (get_user(flags, (u32 __user *)(argp + flags_offset)))
+ goto out;
+
+ if (flags & KVM_MEM_PRIVATE)
+ size = sizeof(struct kvm_userspace_memory_region_ext);
+ else
+ size = sizeof(struct kvm_userspace_memory_region);
+
+ if (copy_from_user(&mem, argp, size))
goto out;
r = -EINVAL;
- if (mem.flags & KVM_MEM_PRIVATE)
+ if ((flags ^ mem.flags) & KVM_MEM_PRIVATE)
goto out;
r = kvm_vm_ioctl_set_memory_region(kvm, &mem);
--
2.25.1
