KVM: selftests: Add test case for MMIO during vectoring on x86

Extend the 'set_memory_region_test' with an x86-only test case which
covers emulated MMIO during event 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 userspace gets the correct exit reason, suberror code, and
   GPA in internal.data[3]

Opportunistically add a definition for a non-canonical address to
processor.h so that the source of the #GP is somewhat self-documenting,
and so that future tests don't have to reinvent the wheel.

Signed-off-by: Ivan Orlov <iorlov@amazon.com>
Link: https://lore.kernel.org/r/20241217181458.68690-8-iorlov@amazon.com
[sean: massage changelog]
Signed-off-by: Sean Christopherson <seanjc@google.com>

diff --git a/tools/testing/selftests/kvm/include/x86/processor.h b/tools/testing/selftests/kvm/include/x86/processor.h
index daa02b85127353a2c783daf99c1ba95a6b1292a0..d60da89667729fab7cc177e087e07e8f48677f4e 100644 (file)
--- a/tools/testing/selftests/kvm/include/x86/processor.h
+++ b/tools/testing/selftests/kvm/include/x86/processor.h
@@ -27,6 +27,8 @@ extern uint64_t guest_tsc_khz;
 #define MAX_NR_CPUID_ENTRIES 100
 #endif
 
+#define NONCANONICAL 0xaaaaaaaaaaaaaaaaull
+
 /* Forced emulation prefix, used to invoke the emulator unconditionally. */
 #define KVM_FEP "ud2; .byte 'k', 'v', 'm';"
 

diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
index 621a227e2bf2940e89eecf39cf0f779bef143dd0..bc440d5aba57600a2a58d1b9c5bdee80942015a5 100644 (file)
--- 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();