[PATCH v2 6/6] selftests: KVM: Add test case for MMIO during vectoring

Ivan Orlov
2024-11-11T10:28:15Z

Extend the 'set_memory_region_test' with a test case which covers the
MMIO during vectoring error handling. The test case

1) Sets an IDT descriptor base to point to an MMIO address
2) Generates a #GP in the guest
3) Verifies that we got a correct exit reason and suberror code
4) Verifies that we got a corrent reported GPA in internal.data[3]

Also, add a definition of non-canonical address to processor.h

Signed-off-by: Ivan Orlov <iorlov@amazon.com>
---
V1 -> V2:
- Get rid of pronouns, redundant comments and incorrect wording
- Define noncanonical address in processor.h
- Fix indentation and wrap lines at 80 columns

.../selftests/kvm/include/x86_64/processor.h | 2 +
.../selftests/kvm/set_memory_region_test.c | 51 +++++++++++++++++++
2 files changed, 53 insertions(+)

diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 1a60c99b5833..997df5003edb 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -1165,6 +1165,8 @@ void vm_install_exception_handler(struct kvm_vm *vm, int vector,
/* If a toddler were to say "abracadabra". */
#define KVM_EXCEPTION_MAGIC 0xabacadabaULL

+#define NONCANONICAL 0xaaaaaaaaaaaaaaaaull
+
/*
* KVM selftest exception fixup uses registers to coordinate with the exception
* handler, versus the kernel's in-memory tables and KVM-Unit-Tests's in-memory
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index a1c53cc854a5..d65a9f20aa1a 100644
--- a/tools/testing/selftests/kvm/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -553,6 +553,56 @@ static void test_add_overlapping_private_memory_regions(void)
close(memfd);
kvm_vm_free(vm);
}
+
+static void guest_code_mmio_during_vectoring(void)
+{
+ const struct desc_ptr idt_desc = {
+ .address = MEM_REGION_GPA,
+ .size = 0xFFF,
+ };
+
+ set_idt(&idt_desc);
+
+ /* Generate a #GP by dereferencing a non-canonical address */
+ *((uint8_t *)NONCANONICAL) = 0x1;
+
+ GUEST_ASSERT(0);
+}
+
+/*
+ * This test points the IDT descriptor base to an MMIO address. It should cause
+ * a KVM internal error when an event occurs in the guest.
+ */
+static void test_mmio_during_vectoring(void)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_run *run;
+ struct kvm_vm *vm;
+ u64 expected_gpa;
+
+ pr_info("Testing MMIO during vectoring error handling\n");
+
+ vm = vm_create_with_one_vcpu(&vcpu, guest_code_mmio_during_vectoring);
+ virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 1);
+
+ run = vcpu->run;
+
+ vcpu_run(vcpu);
+ TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_INTERNAL_ERROR);
+ TEST_ASSERT(run->internal.suberror == KVM_INTERNAL_ERROR_DELIVERY_EV,
+ "Unexpected suberror = %d", vcpu->run->internal.suberror);
+ TEST_ASSERT(run->internal.ndata != 4, "Unexpected internal error data array size = %d",
+ run->internal.ndata);
+
+ /* The reported GPA should be IDT base + offset of the GP vector */
+ expected_gpa = MEM_REGION_GPA + GP_VECTOR * sizeof(struct idt_entry);
+
+ TEST_ASSERT(run->internal.data[3] == expected_gpa,
+ "Unexpected GPA = %llx (expected %lx)",
+ vcpu->run->internal.data[3], expected_gpa);
+
+ kvm_vm_free(vm);
+}
#endif

int main(int argc, char *argv[])
@@ -568,6 +618,7 @@ int main(int argc, char *argv[])
* KVM_RUN fails with ENOEXEC or EFAULT.
*/
test_zero_memory_regions();
+ test_mmio_during_vectoring();
#endif

test_invalid_memory_region_flags();
--
2.43.0