On Wed, Nov 10, 2021 at 4:03 PM David Matlack <dmatlack@xxxxxxxxxx> wrote:
>
> From: Sean Christopherson <seanjc@xxxxxxxxxx>
>
> Assert that the GPA for a memslot backed by a hugepage is aligned to
> the hugepage size and fix perf_test_util accordingly. Lack of GPA
> alignment prevents KVM from backing the guest with hugepages, e.g. x86's
> write-protection of hugepages when dirty logging is activated is
> otherwise not exercised.
>
> Add a comment explaining that guest_page_size is for non-huge pages to
> try and avoid confusion about what it actually tracks.
>
> Cc: Ben Gardon <bgardon@xxxxxxxxxx>
> Cc: Yanan Wang <wangyanan55@xxxxxxxxxx>
> Cc: Andrew Jones <drjones@xxxxxxxxxx>
> Cc: Peter Xu <peterx@xxxxxxxxxx>
> Cc: Aaron Lewis <aaronlewis@xxxxxxxxxx>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> [Used get_backing_src_pagesz() to determine alignment dynamically.]
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/lib/kvm_util.c | 2 ++
> tools/testing/selftests/kvm/lib/perf_test_util.c | 7 ++++++-
> 2 files changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index 07f37456bba0..1f6a01c33dce 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -875,6 +875,8 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> if (src_type == VM_MEM_SRC_ANONYMOUS_THP)
> alignment = max(backing_src_pagesz, alignment);
>
> + ASSERT_EQ(guest_paddr, align_up(guest_paddr, backing_src_pagesz));
> +
> /* Add enough memory to align up if necessary */
> if (alignment > 1)
> region->mmap_size += alignment;
> diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
> index 6b8d5020dc54..a015f267d945 100644
> --- a/tools/testing/selftests/kvm/lib/perf_test_util.c
> +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
> @@ -55,11 +55,16 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
> {
> struct kvm_vm *vm;
> uint64_t guest_num_pages;
> + uint64_t backing_src_pagesz = get_backing_src_pagesz(backing_src);
> int i;
>
> pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
>
> perf_test_args.host_page_size = getpagesize();
> + /*
> + * Snapshot the non-huge page size. This is used by the guest code to
> + * access/dirty pages at the logging granularity.
> + */
> perf_test_args.guest_page_size = vm_guest_mode_params[mode].page_size;
Is this comment correct? I wouldn't expect the guest page size to
determine the host dirty logging granularity.
>
> guest_num_pages = vm_adjust_num_guest_pages(mode,
> @@ -92,7 +97,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int vcpus,
>
> guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
> perf_test_args.guest_page_size;
> - guest_test_phys_mem = align_down(guest_test_phys_mem, perf_test_args.host_page_size);
> + guest_test_phys_mem = align_down(guest_test_phys_mem, backing_src_pagesz);
> #ifdef __s390x__
> /* Align to 1M (segment size) */
> guest_test_phys_mem = align_down(guest_test_phys_mem, 1 << 20);
> --
> 2.34.0.rc1.387.gb447b232ab-goog
>
