On 29/11/18 17:08, Andrew Jones wrote:
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
> Signed-off-by: Andrew Jones <drjones@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/lib/ucall.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/ucall.c b/tools/testing/selftests/kvm/lib/ucall.c
> index 4777f9bb5194..decb595c2965 100644
> --- a/tools/testing/selftests/kvm/lib/ucall.c
> +++ b/tools/testing/selftests/kvm/lib/ucall.c
> @@ -58,7 +58,7 @@ void ucall_init(struct kvm_vm *vm, ucall_type_t type, void *arg)
> start = 1ul << (vm->va_bits * 2 / 3);
> end = 1ul << vm->va_bits;
> step = 1ul << (vm->va_bits / 6);
> - for (gpa = start; gpa >= 0; gpa -= step) {
> + for (gpa = start; gpa < end; gpa -= step) {
> if (ucall_mmio_init(vm, gpa & ~(vm->page_size - 1)))
> return;
> }
>
Uhm, I'm confused. The 1/6 address space means that in practice you'll
only do a few tries. Also, going too much down towards the beginning of
the address space is probably not what you want.
What about this:
diff --git a/tools/testing/selftests/kvm/lib/ucall.c
b/tools/testing/selftests/kvm/lib/ucall.c
index decb595c2965..694bc2eaa63e 100644
--- a/tools/testing/selftests/kvm/lib/ucall.c
+++ b/tools/testing/selftests/kvm/lib/ucall.c
@@ -34,7 +34,7 @@ void ucall_init(struct kvm_vm *vm, ucall_type_t type,
void *arg)
return;
if (type == UCALL_MMIO) {
- vm_paddr_t gpa, start, end, step;
+ vm_paddr_t gpa, start, end, step, offset;
bool ret;
if (arg) {
@@ -53,17 +53,15 @@ void ucall_init(struct kvm_vm *vm, ucall_type_t
type, void *arg)
* KVM_EXIT_MMIO. Well, at least that's how it works for AArch64.
* Here we start with a guess that the addresses around two
* thirds of the VA space are unmapped and then work both down
- * and up from there in 1/6 VA space sized steps.
+ * and up from there in 1/12 VA space sized steps.
*/
start = 1ul << (vm->va_bits * 2 / 3);
end = 1ul << vm->va_bits;
- step = 1ul << (vm->va_bits / 6);
- for (gpa = start; gpa < end; gpa -= step) {
- if (ucall_mmio_init(vm, gpa & ~(vm->page_size - 1)))
+ step = 1ul << (vm->va_bits / 12);
+ for (offset = 0; offset < end - start; offset += step) {
+ if (ucall_mmio_init(vm, (gpa - offset) & ~(vm->page_size - 1)))
return;
- }
- for (gpa = start + step; gpa < end; gpa += step) {
- if (ucall_mmio_init(vm, gpa & ~(vm->page_size - 1)))
+ if (ucall_mmio_init(vm, (gpa + offset) & ~(vm->page_size - 1)))
return;
}
TEST_ASSERT(false, "Can't find a ucall mmio address");
Paolo
