On Tue, Jul 09, 2024, Peter Gonda wrote:
Regression test for ae20eef5 ("KVM: SVM: Update SEV-ES shutdown intercepts with more metadata"). Test confirms userspace is correctly indicated of a guest shutdown not previous behavior of an EINVAL from KVM_RUN.
Cc: Paolo Bonzini pbonzini@redhat.com Cc: Sean Christopherson seanjc@google.com Cc: Alper Gun alpergun@google.com Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Michael Roth michael.roth@amd.com Cc: kvm@vger.kernel.org Cc: linux-kselftest@vger.kernel.org Signed-off-by: Peter Gonda pgonda@google.com
.../selftests/kvm/x86_64/sev_smoke_test.c | 26 +++++++++++++++++++ 1 file changed, 26 insertions(+)
diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c index 7c70c0da4fb74..04f24d5f09877 100644 --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c @@ -160,6 +160,30 @@ static void test_sev(void *guest_code, uint64_t policy) kvm_vm_free(vm); } +static void guest_shutdown_code(void) +{
- __asm__ __volatile__("ud2");
Heh, this passes by dumb luck, not because the #UD itself causes a SHUTDOWN. It _looks_ like the #UD causes a shutdown, because KVM will always see the original guest RIP, but the shutdown actually occurs somewhere in the ucall_assert() in route_exception().
Now that x86 selftests install an IDT and exception handlers by default, it's actually quite hard to induce shutdown. Ok, not "hard", but it requires more work than simply generating a #UD.
I'll add this as fixup when applying:
diff --git a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c index 04f24d5f0987..2e9197eb1652 100644 --- a/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c +++ b/tools/testing/selftests/kvm/x86_64/sev_smoke_test.c @@ -162,6 +162,12 @@ static void test_sev(void *guest_code, uint64_t policy)
static void guest_shutdown_code(void) { + struct desc_ptr idt; + + /* Clobber the IDT so that #UD is guaranteed to trigger SHUTDOWN. */ + memset(&idt, 0, sizeof(idt)); + __asm__ __volatile__("lidt %0" :: "m"(idt)); + __asm__ __volatile__("ud2"); }