Re: [PATCH v2 05/10] KVM: selftests: allow different backing source types

[Ben Gardon]

On Wed, May 19, 2021 at 1:03 PM Axel Rasmussen <axelrasmussen@xxxxxxxxxx> wrote:
>
> Add an argument which lets us specify a different backing memory type
> for the test. The default is just to use anonymous, matching existing
> behavior.
>
> This is in preparation for testing UFFD minor faults. For that, we'll
> need to use a new backing memory type which is setup with MAP_SHARED.
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>

Reviewed-by: Ben Gardon <bgardon@xxxxxxxxxx>

> ---
>  tools/testing/selftests/kvm/demand_paging_test.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
> index 94cf047358d5..01890a7b0155 100644
> --- a/tools/testing/selftests/kvm/demand_paging_test.c
> +++ b/tools/testing/selftests/kvm/demand_paging_test.c
> @@ -241,6 +241,7 @@ static void setup_demand_paging(struct kvm_vm *vm,
>  struct test_params {
>         bool use_uffd;
>         useconds_t uffd_delay;
> +       enum vm_mem_backing_src_type src_type;
>         bool partition_vcpu_memory_access;
>  };
>
> @@ -258,11 +259,11 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>         int r;
>
>         vm = perf_test_create_vm(mode, nr_vcpus, guest_percpu_mem_size,
> -                                VM_MEM_SRC_ANONYMOUS);
> +                                p->src_type);
>
>         perf_test_args.wr_fract = 1;
>
> -       demand_paging_size = get_backing_src_pagesz(VM_MEM_SRC_ANONYMOUS);
> +       demand_paging_size = get_backing_src_pagesz(p->src_type);
>
>         guest_data_prototype = malloc(demand_paging_size);
>         TEST_ASSERT(guest_data_prototype,
> @@ -378,7 +379,7 @@ static void help(char *name)
>  {
>         puts("");
>         printf("usage: %s [-h] [-m mode] [-u] [-d uffd_delay_usec]\n"
> -              "          [-b memory] [-v vcpus] [-o]\n", name);
> +              "          [-b memory] [-t type] [-v vcpus] [-o]\n", name);
>         guest_modes_help();
>         printf(" -u: use User Fault FD to handle vCPU page\n"
>                "     faults.\n");
> @@ -388,6 +389,8 @@ static void help(char *name)
>         printf(" -b: specify the size of the memory region which should be\n"
>                "     demand paged by each vCPU. e.g. 10M or 3G.\n"
>                "     Default: 1G\n");
> +       printf(" -t: The type of backing memory to use. Default: anonymous\n");
> +       backing_src_help();
>         printf(" -v: specify the number of vCPUs to run.\n");
>         printf(" -o: Overlap guest memory accesses instead of partitioning\n"
>                "     them into a separate region of memory for each vCPU.\n");
> @@ -399,13 +402,14 @@ int main(int argc, char *argv[])
>  {
>         int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
>         struct test_params p = {
> +               .src_type = VM_MEM_SRC_ANONYMOUS,
>                 .partition_vcpu_memory_access = true,
>         };
>         int opt;
>
>         guest_modes_append_default();
>
> -       while ((opt = getopt(argc, argv, "hm:ud:b:v:o")) != -1) {
> +       while ((opt = getopt(argc, argv, "hm:ud:b:t:v:o")) != -1) {
>                 switch (opt) {
>                 case 'm':
>                         guest_modes_cmdline(optarg);
> @@ -420,6 +424,9 @@ int main(int argc, char *argv[])
>                 case 'b':
>                         guest_percpu_mem_size = parse_size(optarg);
>                         break;
> +               case 't':
> +                       p.src_type = parse_backing_src_type(optarg);
> +                       break;
>                 case 'v':
>                         nr_vcpus = atoi(optarg);
>                         TEST_ASSERT(nr_vcpus > 0 && nr_vcpus <= max_vcpus,
> --
> 2.31.1.751.gd2f1c929bd-goog
>