kvm: selftest: pass in extra memory when create vm

This information can be used to decide the size of the default memory
slot, which will need to cover the extra pages with page tables.

Signed-off-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/tools/testing/selftests/kvm/lib/x86.c b/tools/testing/selftests/kvm/lib/x86.c
index e38345252df5..a3122f1949a8 100644
--- a/tools/testing/selftests/kvm/lib/x86.c
+++ b/tools/testing/selftests/kvm/lib/x86.c
@@ -702,6 +702,9 @@ void vcpu_set_cpuid(struct kvm_vm *vm,
  *
  * Input Args:
  *   vcpuid - The id of the single VCPU to add to the VM.
+ *   extra_mem_pages - The size of extra memories to add (this will
+ *                     decide how much extra space we will need to
+ *                     setup the page tables using mem slot 0)
  *   guest_code - The vCPU's entry point
  *
  * Output Args: None
@@ -709,12 +712,23 @@ void vcpu_set_cpuid(struct kvm_vm *vm,
  * Return:
  *   Pointer to opaque structure that describes the created VM.
  */
-struct kvm_vm *vm_create_default(uint32_t vcpuid, void *guest_code)
+struct kvm_vm *vm_create_default(uint32_t vcpuid, uint64_t extra_mem_pages,
+				 void *guest_code)
 {
 	struct kvm_vm *vm;
+	/*
+	 * For x86 the maximum page table size for a memory region
+	 * will be when only 4K pages are used.  In that case the
+	 * total extra size for page tables (for extra N pages) will
+	 * be: N/512+N/512^2+N/512^3+... which is definitely smaller
+	 * than N/512*2.
+	 */
+	uint64_t extra_pg_pages = extra_mem_pages / 512 * 2;
 
 	/* Create VM */
-	vm = vm_create(VM_MODE_FLAT48PG, DEFAULT_GUEST_PHY_PAGES, O_RDWR);
+	vm = vm_create(VM_MODE_FLAT48PG,
+		       DEFAULT_GUEST_PHY_PAGES + extra_pg_pages,
+		       O_RDWR);
 
 	/* Setup guest code */
 	kvm_vm_elf_load(vm, program_invocation_name, 0, 0);