On Wed, Sep 17, 2025 at 02:48:38PM -0700, Jim Mattson wrote: > Walk the guest page tables via a loop when searching for a PTE, > instead of using unique variables for each level of the page tables. > > This simplifies the code and makes it easier to support 5-level paging > in the future. > > Signed-off-by: Jim Mattson <[email protected]> > --- > .../testing/selftests/kvm/lib/x86/processor.c | 21 +++++++------------ > 1 file changed, 8 insertions(+), 13 deletions(-) > > diff --git a/tools/testing/selftests/kvm/lib/x86/processor.c > b/tools/testing/selftests/kvm/lib/x86/processor.c > index 0238e674709d..433365c8196d 100644 > --- a/tools/testing/selftests/kvm/lib/x86/processor.c > +++ b/tools/testing/selftests/kvm/lib/x86/processor.c > @@ -270,7 +270,8 @@ static bool vm_is_target_pte(uint64_t *pte, int *level, > int current_level) > uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr, > int *level) > { > - uint64_t *pml4e, *pdpe, *pde; > + uint64_t *pte = &vm->pgd; > + int current_level; > > TEST_ASSERT(!vm->arch.is_pt_protected, > "Walking page tables of protected guests is impossible"); > @@ -291,19 +292,13 @@ uint64_t *__vm_get_page_table_entry(struct kvm_vm *vm, > uint64_t vaddr, > TEST_ASSERT(vaddr == (((int64_t)vaddr << 16) >> 16), > "Canonical check failed. The virtual address is invalid."); > > - pml4e = virt_get_pte(vm, &vm->pgd, vaddr, PG_LEVEL_512G); > - if (vm_is_target_pte(pml4e, level, PG_LEVEL_512G)) > - return pml4e; > - > - pdpe = virt_get_pte(vm, pml4e, vaddr, PG_LEVEL_1G); > - if (vm_is_target_pte(pdpe, level, PG_LEVEL_1G)) > - return pdpe; > - > - pde = virt_get_pte(vm, pdpe, vaddr, PG_LEVEL_2M); > - if (vm_is_target_pte(pde, level, PG_LEVEL_2M)) > - return pde; > + for (current_level = vm->pgtable_levels; current_level > 0; > current_level--) {
This should be current_level >= PG_LEVEL_4K. It's the same, but easier to read. > + pte = virt_get_pte(vm, pte, vaddr, current_level); > + if (vm_is_target_pte(pte, level, current_level)) Seems like vm_is_target_pte() is written with the assumption that it operates on an upper-level PTE, but I think it works on 4K PTEs as well. > + return pte; > + } > > - return virt_get_pte(vm, pde, vaddr, PG_LEVEL_4K); > + return pte; > } > > uint64_t *vm_get_page_table_entry(struct kvm_vm *vm, uint64_t vaddr) > -- > 2.51.0.470.ga7dc726c21-goog >
