KVM: Add kernel-internal memory slots
Reserve a few memory slots for kernel internal use. This is good for case
you have to register memory region and you want to be sure it was not
registered from userspace, and for case you want to register a memory region
that won't be seen from userspace.
Signed-off-by: Izik Eidus <izike@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/drivers/kvm/kvm_main.c b/drivers/kvm/kvm_main.c
index 5113cbf..a044856 100644
--- a/drivers/kvm/kvm_main.c
+++ b/drivers/kvm/kvm_main.c
@@ -660,7 +660,7 @@
goto out;
if (mem->guest_phys_addr & (PAGE_SIZE - 1))
goto out;
- if (mem->slot >= KVM_MEMORY_SLOTS)
+ if (mem->slot >= KVM_MEMORY_SLOTS + KVM_PRIVATE_MEM_SLOTS)
goto out;
if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
goto out;
@@ -797,6 +797,8 @@
kvm_userspace_memory_region *mem,
int user_alloc)
{
+ if (mem->slot >= KVM_MEMORY_SLOTS)
+ return -EINVAL;
return kvm_set_memory_region(kvm, mem, user_alloc);
}
@@ -1010,6 +1012,22 @@
return __gfn_to_memslot(kvm, gfn);
}
+int kvm_is_visible_gfn(struct kvm *kvm, gfn_t gfn)
+{
+ int i;
+
+ gfn = unalias_gfn(kvm, gfn);
+ for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
+ struct kvm_memory_slot *memslot = &kvm->memslots[i];
+
+ if (gfn >= memslot->base_gfn
+ && gfn < memslot->base_gfn + memslot->npages)
+ return 1;
+ }
+ return 0;
+}
+EXPORT_SYMBOL_GPL(kvm_is_visible_gfn);
+
struct page *gfn_to_page(struct kvm *kvm, gfn_t gfn)
{
struct kvm_memory_slot *slot;
@@ -3087,6 +3105,8 @@
struct page *page;
pgoff = ((address - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
+ if (!kvm_is_visible_gfn(kvm, pgoff))
+ return NOPAGE_SIGBUS;
page = gfn_to_page(kvm, pgoff);
if (is_error_page(page)) {
kvm_release_page(page);