[PATCH 1/3] KVM: selftests: evmcs_test: Check that VMLAUNCH with bogus EVMPTR is causing #UD

From: Vitaly Kuznetsov
Date: Wed May 05 2021 - 11:18:40 EST


'run->exit_reason == KVM_EXIT_SHUTDOWN' check is not ideal as we may be
getting some unexpected exception. Directly check for #UD instead.

Signed-off-by: Vitaly Kuznetsov <vkuznets@xxxxxxxxxx>
---
.../testing/selftests/kvm/x86_64/evmcs_test.c | 24 ++++++++++++-------
1 file changed, 16 insertions(+), 8 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/evmcs_test.c b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
index ca22ee6d19cb..b01f64ac6ce3 100644
--- a/tools/testing/selftests/kvm/x86_64/evmcs_test.c
+++ b/tools/testing/selftests/kvm/x86_64/evmcs_test.c
@@ -19,6 +19,14 @@

#define VCPU_ID 5

+static int ud_count;
+
+static void guest_ud_handler(struct ex_regs *regs)
+{
+ ud_count++;
+ regs->rip += 3; /* VMLAUNCH */
+}
+
void l2_guest_code(void)
{
GUEST_SYNC(7);
@@ -71,11 +79,11 @@ void guest_code(struct vmx_pages *vmx_pages)
if (vmx_pages)
l1_guest_code(vmx_pages);

- GUEST_DONE();
-
/* Try enlightened vmptrld with an incorrect GPA */
evmcs_vmptrld(0xdeadbeef, vmx_pages->enlightened_vmcs);
GUEST_ASSERT(vmlaunch());
+ GUEST_ASSERT(ud_count == 1);
+ GUEST_DONE();
}

int main(int argc, char *argv[])
@@ -109,6 +117,10 @@ int main(int argc, char *argv[])
vcpu_alloc_vmx(vm, &vmx_pages_gva);
vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);

+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vm, VCPU_ID);
+ vm_handle_exception(vm, UD_VECTOR, guest_ud_handler);
+
for (stage = 1;; stage++) {
_vcpu_run(vm, VCPU_ID);
TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
@@ -124,7 +136,7 @@ int main(int argc, char *argv[])
case UCALL_SYNC:
break;
case UCALL_DONE:
- goto part1_done;
+ goto done;
default:
TEST_FAIL("Unknown ucall %lu", uc.cmd);
}
@@ -156,10 +168,6 @@ int main(int argc, char *argv[])
(ulong) regs2.rdi, (ulong) regs2.rsi);
}

-part1_done:
- _vcpu_run(vm, VCPU_ID);
- TEST_ASSERT(run->exit_reason == KVM_EXIT_SHUTDOWN,
- "Unexpected successful VMEnter with invalid eVMCS pointer!");
-
+done:
kvm_vm_free(vm);
}
--
2.30.2