[PATCH v4 11/16] KVM: selftests: Precisely limit the number of guest loops in mmu_stress_test

Sean Christopherson
2024-11-28T02:22:15Z

Run the exact number of guest loops required in mmu_stress_test instead
of looping indefinitely in anticipation of adding more stages that run
different code (e.g. reads instead of writes).

Reviewed-by: James Houghton <jthoughton@google.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
tools/testing/selftests/kvm/mmu_stress_test.c | 25 ++++++++++++++-----
1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/kvm/mmu_stress_test.c b/tools/testing/selftests/kvm/mmu_stress_test.c
index 656a837c7f49..c6bf18cb7c89 100644
--- a/tools/testing/selftests/kvm/mmu_stress_test.c
+++ b/tools/testing/selftests/kvm/mmu_stress_test.c
@@ -20,12 +20,15 @@
static void guest_code(uint64_t start_gpa, uint64_t end_gpa, uint64_t stride)
{
uint64_t gpa;
+ int i;

- for (;;) {
+ for (i = 0; i < 2; i++) {
for (gpa = start_gpa; gpa < end_gpa; gpa += stride)
vcpu_arch_put_guest(*((volatile uint64_t *)gpa), gpa);
- GUEST_SYNC(0);
+ GUEST_SYNC(i);
}
+
+ GUEST_ASSERT(0);
}

struct vcpu_info {
@@ -52,10 +55,18 @@ static void rendezvous_with_boss(void)
}
}

-static void run_vcpu(struct kvm_vcpu *vcpu)
+static void assert_sync_stage(struct kvm_vcpu *vcpu, int stage)
+{
+ struct ucall uc;
+
+ TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_SYNC);
+ TEST_ASSERT_EQ(uc.args[1], stage);
+}
+
+static void run_vcpu(struct kvm_vcpu *vcpu, int stage)
{
vcpu_run(vcpu);
- TEST_ASSERT_EQ(get_ucall(vcpu, NULL), UCALL_SYNC);
+ assert_sync_stage(vcpu, stage);
}

static void *vcpu_worker(void *data)
@@ -69,7 +80,8 @@ static void *vcpu_worker(void *data)

rendezvous_with_boss();

- run_vcpu(vcpu);
+ /* Stage 0, write all of guest memory. */
+ run_vcpu(vcpu, 0);
rendezvous_with_boss();
#ifdef __x86_64__
vcpu_sregs_get(vcpu, &sregs);
@@ -79,7 +91,8 @@ static void *vcpu_worker(void *data)
#endif
rendezvous_with_boss();

- run_vcpu(vcpu);
+ /* Stage 1, re-write all of guest memory. */
+ run_vcpu(vcpu, 1);
rendezvous_with_boss();

return NULL;