The KVM Userfault mode checks that we are able to resolve KVM Userfaults
and the vCPUs will continue to make progress. It initially sets all of
guest memory as KVM_MEMORY_ATTRIBUTE_USERFAULT, then, as the test runs,
clears the attribute from pages as they are faulted on.
This test does not currently check for asynchronous page faults.
Signed-off-by: James Houghton <jthoughton@xxxxxxxxxx>
---
.../selftests/kvm/demand_paging_test.c | 46 ++++++++++++++++++-
1 file changed, 44 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
index 0202b78f8680..8654b58091b2 100644
--- a/tools/testing/selftests/kvm/demand_paging_test.c
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -28,6 +28,13 @@ static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
static size_t demand_paging_size;
static char *guest_data_prototype;
+bool userfault_enabled = false;
+
+static void resolve_kvm_userfault(u64 gpa, u64 size)
+{
+ /* Toggle KVM_MEMORY_ATTRIBUTE_USERFAULT off */
+ vm_set_memory_attributes(memstress_args.vm, gpa, size, 0);
+}
static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
{
@@ -41,8 +48,22 @@ static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
clock_gettime(CLOCK_MONOTONIC, &start);
/* Let the guest access its memory */
+restart:
ret = _vcpu_run(vcpu);
- TEST_ASSERT(ret == 0, "vcpu_run failed: %d", ret);
+ if (ret < 0 && errno == EFAULT && userfault_enabled) {
+ /* Check for userfault. */
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_MEMORY_FAULT,
+ "Got invalid exit reason: %llx", run->exit_reason);
+ TEST_ASSERT(run->memory_fault.flags ==
+ KVM_MEMORY_EXIT_FLAG_USERFAULT,
+ "Got invalid memory fault exit: %llx",
+ run->memory_fault.flags);
+ resolve_kvm_userfault(run->memory_fault.gpa,
+ run->memory_fault.size);
+ goto restart;
+ } else
+ TEST_ASSERT(ret == 0, "vcpu_run failed: %d", ret);
+
if (get_ucall(vcpu, NULL) != UCALL_SYNC) {
TEST_ASSERT(false,
"Invalid guest sync status: exit_reason=%s",
@@ -136,6 +157,7 @@ struct test_params {
int readers_per_uffd;
enum vm_mem_backing_src_type src_type;
bool partition_vcpu_memory_access;
+ bool kvm_userfault;
};
static void prefault_mem(void *alias, uint64_t len)
@@ -206,6 +228,17 @@ static void run_test(enum vm_guest_mode mode, void *arg)
}
}
+ if (p->kvm_userfault) {
+ TEST_REQUIRE(kvm_has_cap(KVM_CAP_USERFAULT));
+ vm_enable_cap(vm, KVM_CAP_USERFAULT, KVM_USERFAULT_ENABLE);
+ TEST_REQUIRE(kvm_check_cap(KVM_CAP_MEMORY_ATTRIBUTES) &
+ KVM_MEMORY_ATTRIBUTE_USERFAULT);
+ vm_set_memory_attributes(vm, memstress_args.gpa,
+ memstress_args.size,
+ KVM_MEMORY_ATTRIBUTE_USERFAULT);
+ userfault_enabled = true;
+ }
+
pr_info("Finished creating vCPUs and starting uffd threads\n");
clock_gettime(CLOCK_MONOTONIC, &start);
@@ -232,6 +265,11 @@ static void run_test(enum vm_guest_mode mode, void *arg)
pr_info("Overall demand paging rate:\t%f pgs/sec\n",
vcpu_paging_rate * nr_vcpus);
+ if (p->kvm_userfault) {
+ vm_enable_cap(vm, KVM_CAP_USERFAULT, KVM_USERFAULT_DISABLE);
+ userfault_enabled = false;
+ }
+
memstress_destroy_vm(vm);
free(guest_data_prototype);
@@ -263,6 +301,7 @@ static void help(char *name)
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");
+ printf(" -k: Use KVM Userfault\n");
puts("");
exit(0);
}
@@ -281,7 +320,7 @@ int main(int argc, char *argv[])
guest_modes_append_default();
- while ((opt = getopt(argc, argv, "ahom:u:d:b:s:v:c:r:")) != -1) {
+ while ((opt = getopt(argc, argv, "ahokm:u:d:b:s:v:c:r:")) != -1) {
switch (opt) {
case 'm':
guest_modes_cmdline(optarg);
@@ -324,6 +363,9 @@ int main(int argc, char *argv[])
"Invalid number of readers per uffd %d: must be >=1",
p.readers_per_uffd);
break;
+ case 'k':
+ p.kvm_userfault = true;
+ break;
case 'h':
default:
help(argv[0]);
--
2.45.2.993.g49e7a77208-goog
