[PATCH v2 4/5] KVM: selftests: Add wrfract to common guest code

From: Ben Gardon
Date: Tue Nov 03 2020 - 18:50:08 EST


Wrfract will be used by the dirty logging perf test introduced later in
this series to dirty memory sparsely.

Signed-off-by: Ben Gardon <bgardon@xxxxxxxxxx>
---
tools/testing/selftests/kvm/demand_paging_test.c | 2 ++
tools/testing/selftests/kvm/include/perf_test_util.h | 1 +
tools/testing/selftests/kvm/lib/perf_test_util.c | 5 ++++-
3 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 63ea7c06e1141..72b8890c0dc3b 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -264,6 +264,8 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
int vcpu_id;
int r;

+ perf_test_args.wr_fract = 1;
+
vm = create_vm(mode, vcpus, vcpu_memory_bytes);

guest_data_prototype = malloc(perf_test_args.host_page_size);
diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h
index 4d52b9ee13c42..645b942ae0229 100644
--- a/tools/testing/selftests/kvm/include/perf_test_util.h
+++ b/tools/testing/selftests/kvm/include/perf_test_util.h
@@ -36,6 +36,7 @@ struct perf_test_args {
struct kvm_vm *vm;
uint64_t host_page_size;
uint64_t guest_page_size;
+ int wr_fract;

struct vcpu_args vcpu_args[MAX_VCPUS];
};
diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
index fa7efbac9ef8a..1abb6b1321c3c 100644
--- a/tools/testing/selftests/kvm/lib/perf_test_util.c
+++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
@@ -44,7 +44,10 @@ void guest_code(uint32_t vcpu_id)
for (i = 0; i < pages; i++) {
uint64_t addr = gva + (i * perf_test_args.guest_page_size);

- *(uint64_t *)addr = 0x0123456789ABCDEF;
+ if (i % perf_test_args.wr_fract == 0)
+ *(uint64_t *)addr = 0x0123456789ABCDEF;
+ else
+ READ_ONCE(*(uint64_t *)addr);
}

GUEST_SYNC(1);
--
2.29.1.341.ge80a0c044ae-goog