On Wed, Nov 10, 2021 at 4:03 PM David Matlack <dmatlack@xxxxxxxxxx> wrote:
>
> From: Sean Christopherson <seanjc@xxxxxxxxxx>
>
> Refactor align() to work with non-pointers and split into separate
> helpers for aligning up vs. down. Add align_ptr_up() for use with
> pointers. Expose all helpers so that they can be used by tests and/or
> other utilities. The align_down() helper in particular will be used to
> ensure gpa alignment for hugepages.
>
> No functional change intended.
>
> Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
> [Added sepearate up/down helpers and replaced open-coded alignment
Nit: separate
> bit math throughout the KVM selftests.]
> Signed-off-by: David Matlack <dmatlack@xxxxxxxxxx>
Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>
This is wonderful.
> ---
> tools/testing/selftests/kvm/dirty_log_test.c | 6 ++---
> .../testing/selftests/kvm/include/test_util.h | 25 +++++++++++++++++++
> .../selftests/kvm/kvm_page_table_test.c | 2 +-
> tools/testing/selftests/kvm/lib/elf.c | 3 +--
> tools/testing/selftests/kvm/lib/kvm_util.c | 13 ++--------
> .../selftests/kvm/lib/perf_test_util.c | 4 +--
> 6 files changed, 34 insertions(+), 19 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> index 792c60e1b17d..3fcd89e195c7 100644
> --- a/tools/testing/selftests/kvm/dirty_log_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> @@ -115,7 +115,7 @@ static void guest_code(void)
> addr = guest_test_virt_mem;
> addr += (READ_ONCE(random_array[i]) % guest_num_pages)
> * guest_page_size;
> - addr &= ~(host_page_size - 1);
> + addr = align_down(addr, host_page_size);
> *(uint64_t *)addr = READ_ONCE(iteration);
> }
>
> @@ -737,14 +737,14 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> if (!p->phys_offset) {
> guest_test_phys_mem = (vm_get_max_gfn(vm) -
> guest_num_pages) * guest_page_size;
> - guest_test_phys_mem &= ~(host_page_size - 1);
> + guest_test_phys_mem = align_down(guest_test_phys_mem, host_page_size);
> } else {
> guest_test_phys_mem = p->phys_offset;
> }
>
> #ifdef __s390x__
> /* Align to 1M (segment size) */
> - guest_test_phys_mem &= ~((1 << 20) - 1);
> + guest_test_phys_mem = align_down(guest_test_phys_mem, 1 << 20);
> #endif
>
> pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
> diff --git a/tools/testing/selftests/kvm/include/test_util.h b/tools/testing/selftests/kvm/include/test_util.h
> index f8fddc84c0d3..78c06310cc0e 100644
> --- a/tools/testing/selftests/kvm/include/test_util.h
> +++ b/tools/testing/selftests/kvm/include/test_util.h
> @@ -117,4 +117,29 @@ static inline bool backing_src_is_shared(enum vm_mem_backing_src_type t)
> return vm_mem_backing_src_alias(t)->flag & MAP_SHARED;
> }
>
> +/* Aligns x up to the next multiple of size. Size must be a power of 2. */
> +static inline uint64_t align_up(uint64_t x, uint64_t size)
> +{
> + uint64_t mask = size - 1;
> +
> + TEST_ASSERT(size != 0 && !(size & (size - 1)),
> + "size not a power of 2: %lu", size);
> + return ((x + mask) & ~mask);
> +}
> +
> +static inline uint64_t align_down(uint64_t x, uint64_t size)
> +{
> + uint64_t x_aligned_up = align_up(x, size);
> +
> + if (x == x_aligned_up)
> + return x;
> + else
> + return x_aligned_up - size;
> +}
> +
> +static inline void *align_ptr_up(void *x, size_t size)
> +{
> + return (void *)align_up((unsigned long)x, size);
> +}
> +
> #endif /* SELFTEST_KVM_TEST_UTIL_H */
> diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> index 36407cb0ec85..3836322add00 100644
> --- a/tools/testing/selftests/kvm/kvm_page_table_test.c
> +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> @@ -280,7 +280,7 @@ static struct kvm_vm *pre_init_before_test(enum vm_guest_mode mode, void *arg)
> #ifdef __s390x__
> alignment = max(0x100000, alignment);
> #endif
> - guest_test_phys_mem &= ~(alignment - 1);
> + guest_test_phys_mem = align_down(guest_test_virt_mem, alignment);
>
> /* Set up the shared data structure test_args */
> test_args.vm = vm;
> diff --git a/tools/testing/selftests/kvm/lib/elf.c b/tools/testing/selftests/kvm/lib/elf.c
> index eac44f5d0db0..13e8e3dcf984 100644
> --- a/tools/testing/selftests/kvm/lib/elf.c
> +++ b/tools/testing/selftests/kvm/lib/elf.c
> @@ -157,8 +157,7 @@ void kvm_vm_elf_load(struct kvm_vm *vm, const char *filename)
> "memsize of 0,\n"
> " phdr index: %u p_memsz: 0x%" PRIx64,
> n1, (uint64_t) phdr.p_memsz);
> - vm_vaddr_t seg_vstart = phdr.p_vaddr;
> - seg_vstart &= ~(vm_vaddr_t)(vm->page_size - 1);
> + vm_vaddr_t seg_vstart = align_down(phdr.p_vaddr, vm->page_size);
> vm_vaddr_t seg_vend = phdr.p_vaddr + phdr.p_memsz - 1;
> seg_vend |= vm->page_size - 1;
> size_t seg_size = seg_vend - seg_vstart + 1;
> diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
> index b624c24290dd..63375118d48f 100644
> --- a/tools/testing/selftests/kvm/lib/kvm_util.c
> +++ b/tools/testing/selftests/kvm/lib/kvm_util.c
> @@ -22,15 +22,6 @@
>
> static int vcpu_mmap_sz(void);
>
> -/* Aligns x up to the next multiple of size. Size must be a power of 2. */
> -static void *align(void *x, size_t size)
> -{
> - size_t mask = size - 1;
> - TEST_ASSERT(size != 0 && !(size & (size - 1)),
> - "size not a power of 2: %lu", size);
> - return (void *) (((size_t) x + mask) & ~mask);
> -}
> -
> /*
> * Open KVM_DEV_PATH if available, otherwise exit the entire program.
> *
> @@ -911,7 +902,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> region->mmap_start, errno);
>
> /* Align host address */
> - region->host_mem = align(region->mmap_start, alignment);
> + region->host_mem = align_ptr_up(region->mmap_start, alignment);
>
> /* As needed perform madvise */
> if ((src_type == VM_MEM_SRC_ANONYMOUS ||
> @@ -954,7 +945,7 @@ void vm_userspace_mem_region_add(struct kvm_vm *vm,
> "mmap of alias failed, errno: %i", errno);
>
> /* Align host alias address */
> - region->host_alias = align(region->mmap_alias, alignment);
> + region->host_alias = align_ptr_up(region->mmap_alias, alignment);
> }
> }
>
> diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
> index 0ef80dbdc116..6b8d5020dc54 100644
> --- a/tools/testing/selftests/kvm/lib/perf_test_util.c
> +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
> @@ -92,10 +92,10 @@ 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 &= ~(perf_test_args.host_page_size - 1);
> + guest_test_phys_mem = align_down(guest_test_phys_mem, perf_test_args.host_page_size);
> #ifdef __s390x__
> /* Align to 1M (segment size) */
> - guest_test_phys_mem &= ~((1 << 20) - 1);
> + guest_test_phys_mem = align_down(guest_test_phys_mem, 1 << 20);
> #endif
> pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
>
> --
> 2.34.0.rc1.387.gb447b232ab-goog
>
