Commit feb84f6d authored by Paolo Bonzini's avatar Paolo Bonzini
Browse files

KVM: selftests: document the default implementation of vm_vaddr_populate_bitmap 



Explain the meaning of the bit manipulations of vm_vaddr_populate_bitmap.
These correspond to the "canonical addresses" of x86 and other
architectures, but that is not obvious.

Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 2f5213b8

tools/testing/selftests/kvm/lib/kvm_util.c

+9 −0
Original line number Diff line number Diff line
@@ -186,6 +186,15 @@ const struct vm_guest_mode_params vm_guest_mode_params[] = { 
_Static_assert(sizeof(vm_guest_mode_params)/sizeof(struct vm_guest_mode_params) == NUM_VM_MODES,

	       "Missing new mode params?");



/*

 * Initializes vm->vpages_valid to match the canonical VA space of the

 * architecture.

 *

 * The default implementation is valid for architectures which split the

 * range addressed by a single page table into a low and high region

 * based on the MSB of the VA. On architectures with this behavior

 * the VA region spans [0, 2^(va_bits - 1)), [-(2^(va_bits - 1), -1].

 */

__weak void vm_vaddr_populate_bitmap(struct kvm_vm *vm)

{

	sparsebit_set_num(vm->vpages_valid,