Add selftests for dirty quota throttling with an optional -d parameter
to configure by what value dirty quota should be incremented after
each dirty quota exit. With very small intervals, a smaller value of
dirty quota can ensure that the dirty quota exit code is tested. A zero
value disables dirty quota throttling and thus dirty logging, without
dirty quota throttling, can be tested.
Suggested-by: Shaju Abraham <shaju.abraham@xxxxxxxxxxx>
Suggested-by: Manish Mishra <manish.mishra@xxxxxxxxxxx>
Co-developed-by: Anurag Madnawat <anurag.madnawat@xxxxxxxxxxx>
Signed-off-by: Anurag Madnawat <anurag.madnawat@xxxxxxxxxxx>
Signed-off-by: Shivam Kumar <shivam.kumar1@xxxxxxxxxxx>
---
tools/testing/selftests/kvm/dirty_log_test.c | 33 +++++++++++-
.../selftests/kvm/include/kvm_util_base.h | 4 ++
tools/testing/selftests/kvm/lib/kvm_util.c | 53 +++++++++++++++++++
3 files changed, 88 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
index b5234d6efbe1..a85ca6554d17 100644
--- a/tools/testing/selftests/kvm/dirty_log_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_test.c
@@ -64,6 +64,8 @@
#define SIG_IPI SIGUSR1
+#define TEST_DIRTY_QUOTA_INCREMENT 8
+
/*
* Guest/Host shared variables. Ensure addr_gva2hva() and/or
* sync_global_to/from_guest() are used when accessing from
@@ -190,6 +192,7 @@ static enum log_mode_t host_log_mode_option = LOG_MODE_ALL;
static enum log_mode_t host_log_mode;
static pthread_t vcpu_thread;
static uint32_t test_dirty_ring_count = TEST_DIRTY_RING_COUNT;
+static uint64_t test_dirty_quota_increment = TEST_DIRTY_QUOTA_INCREMENT;
static void vcpu_kick(void)
{
@@ -209,6 +212,13 @@ static void sem_wait_until(sem_t *sem)
while (ret == -1 && errno == EINTR);
}
+static void set_dirty_quota(struct kvm_vm *vm, uint64_t dirty_quota)
+{
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+
+ vcpu_set_dirty_quota(run, dirty_quota);
+}
+
static bool clear_log_supported(void)
{
return kvm_has_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
@@ -256,7 +266,11 @@ static void default_after_vcpu_run(struct kvm_vcpu *vcpu, int ret, int err)
TEST_ASSERT(ret == 0 || (ret == -1 && err == EINTR),
"vcpu run failed: errno=%d", err);
- TEST_ASSERT(get_ucall(vcpu, NULL) == UCALL_SYNC,
+ if (test_dirty_quota_increment &&
+ run->exit_reason == KVM_EXIT_DIRTY_QUOTA_EXHAUSTED)
+ vcpu_handle_dirty_quota_exit(run, test_dirty_quota_increment);
+ else
+ TEST_ASSERT(get_ucall(vcpu, NULL) == UCALL_SYNC,
"Invalid guest sync status: exit_reason=%s\n",
exit_reason_str(run->exit_reason));
@@ -374,6 +388,9 @@ static void dirty_ring_after_vcpu_run(struct kvm_vcpu *vcpu, int ret, int err)
if (get_ucall(vcpu, NULL) == UCALL_SYNC) {
/* We should allow this to continue */
;
+ } else if (test_dirty_quota_increment &&
+ run->exit_reason == KVM_EXIT_DIRTY_QUOTA_EXHAUSTED) {
+ vcpu_handle_dirty_quota_exit(run, test_dirty_quota_increment);
} else if (run->exit_reason == KVM_EXIT_DIRTY_RING_FULL ||
(ret == -1 && err == EINTR)) {
/* Update the flag first before pause */
@@ -764,6 +781,10 @@ static void run_test(enum vm_guest_mode mode, void *arg)
sync_global_to_guest(vm, guest_test_virt_mem);
sync_global_to_guest(vm, guest_num_pages);
+ /* Initialise dirty quota */
+ if (test_dirty_quota_increment)
+ set_dirty_quota(vm, test_dirty_quota_increment);
+
/* Start the iterations */
iteration = 1;
sync_global_to_guest(vm, iteration);
@@ -805,6 +826,9 @@ static void run_test(enum vm_guest_mode mode, void *arg)
/* Tell the vcpu thread to quit */
host_quit = true;
log_mode_before_vcpu_join();
+ /* Terminate dirty quota throttling */
+ if (test_dirty_quota_increment)
+ set_dirty_quota(vm, 0);
pthread_join(vcpu_thread, NULL);
pr_info("Total bits checked: dirty (%"PRIu64"), clear (%"PRIu64"), "
@@ -826,6 +850,8 @@ static void help(char *name)
printf(" -c: specify dirty ring size, in number of entries\n");
printf(" (only useful for dirty-ring test; default: %"PRIu32")\n",
TEST_DIRTY_RING_COUNT);
+ printf(" -q: specify incemental dirty quota (default: %"PRIu32")\n",
+ TEST_DIRTY_QUOTA_INCREMENT);
printf(" -i: specify iteration counts (default: %"PRIu64")\n",
TEST_HOST_LOOP_N);
printf(" -I: specify interval in ms (default: %"PRIu64" ms)\n",
@@ -854,11 +880,14 @@ int main(int argc, char *argv[])
guest_modes_append_default();
- while ((opt = getopt(argc, argv, "c:hi:I:p:m:M:")) != -1) {
+ while ((opt = getopt(argc, argv, "c:q:hi:I:p:m:M:")) != -1) {
switch (opt) {
case 'c':
test_dirty_ring_count = strtol(optarg, NULL, 10);
break;
+ case 'q':
+ test_dirty_quota_increment = strtol(optarg, NULL, 10);
+ break;
case 'i':
p.iterations = strtol(optarg, NULL, 10);
break;
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index e42a09cd24a0..d8eee61a9a7c 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -838,4 +838,8 @@ static inline int __vm_disable_nx_huge_pages(struct kvm_vm *vm)
return __vm_enable_cap(vm, KVM_CAP_VM_DISABLE_NX_HUGE_PAGES, 0);
}
+void vcpu_set_dirty_quota(struct kvm_run *run, uint64_t dirty_quota);
+void vcpu_handle_dirty_quota_exit(struct kvm_run *run,
+ uint64_t test_dirty_quota_increment);
+
#endif /* SELFTEST_KVM_UTIL_BASE_H */
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index f1cb1627161f..2a60c7bdc778 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -18,6 +18,7 @@
#include <linux/kernel.h>
#define KVM_UTIL_MIN_PFN 2
+#define PML_BUFFER_SIZE 512
static int vcpu_mmap_sz(void);
@@ -1745,6 +1746,7 @@ static struct exit_reason {
{KVM_EXIT_X86_RDMSR, "RDMSR"},
{KVM_EXIT_X86_WRMSR, "WRMSR"},
{KVM_EXIT_XEN, "XEN"},
+ {KVM_EXIT_DIRTY_QUOTA_EXHAUSTED, "DIRTY_QUOTA_EXHAUSTED"},
#ifdef KVM_EXIT_MEMORY_NOT_PRESENT
{KVM_EXIT_MEMORY_NOT_PRESENT, "MEMORY_NOT_PRESENT"},
#endif
@@ -2021,3 +2023,54 @@ void __vm_get_stat(struct kvm_vm *vm, const char *stat_name, uint64_t *data,
break;
}
}
+
+bool kvm_is_pml_enabled(void)
+{
+ return is_intel_cpu() && get_kvm_intel_param_bool("pml");
+}
+
+void vcpu_set_dirty_quota(struct kvm_run *run, uint64_t dirty_quota)
+{
+ run->dirty_quota = dirty_quota;
+
+ if (dirty_quota)
+ pr_info("Dirty quota throttling enabled with initial quota %lu\n",
+ dirty_quota);
+ else
+ pr_info("Dirty quota throttling disabled\n");
+}
+
+void vcpu_handle_dirty_quota_exit(struct kvm_run *run,
+ uint64_t test_dirty_quota_increment)
+{
+ uint64_t quota = run->dirty_quota_exit.quota;
+ uint64_t count = run->dirty_quota_exit.count;
+
+ /*
+ * Allow certain pages of overrun, KVM is allowed to dirty multiple
+ * pages before exiting to userspace, e.g. when emulating an
+ * instruction that performs multiple memory accesses.
+ */
+ uint64_t buffer;
+
+ /*
+ * When Intel's Page-Modification Logging (PML) is enabled, the CPU may
+ * dirty up to 512 pages (number of entries in the PML buffer) without
+ * exiting, thus KVM may effectively dirty that many pages before
+ * enforcing the dirty quota.
+ */
+#ifdef __x86_64__
+ if (kvm_is_pml_enabled(void))
+ buffer = PML_BUFFER_SIZE;
+#endif
+
+ TEST_ASSERT(count <= (quota + buffer),
+ "KVM dirtied too many pages: count=%lu, quota=%lu, buffer=%lu\n",
+ count, quota, buffer);
+
+ TEST_ASSERT(count >= quota,
+ "Dirty quota exit happened with quota yet to be exhausted: count=%lu, quota=%lu\n",
+ count, quota);
+
+ run->dirty_quota = count + test_dirty_quota_increment;
+}
--
2.22.3
