[PATCH v3 09/10] KVM: selftests: Expect #PF(RSVD) when TDP is disabled

David Matlack
2022-10-31T18:01:16Z

Change smaller_maxphyaddr_emulation_test to expect a #PF(RSVD), rather
than an emulation failure, when TDP is disabled. KVM only needs to
emulate instructions to emulate a smaller guest.MAXPHYADDR when TDP is
enabled.

Fixes: 39bbcc3a4e39 ("selftests: kvm: Allows userspace to handle emulation errors.")
Signed-off-by: David Matlack <dmatlack@google.com>
---
.../smaller_maxphyaddr_emulation_test.c | 47 ++++++++++++++++---
1 file changed, 41 insertions(+), 6 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
index f438a98e8bb7..5934ddc94aa0 100644
--- a/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
+++ b/tools/testing/selftests/kvm/x86_64/smaller_maxphyaddr_emulation_test.c
@@ -21,9 +21,22 @@
#define MEM_REGION_SLOT 10
#define MEM_REGION_SIZE PAGE_SIZE

-static void guest_code(void)
+static void guest_code(bool tdp_enabled)
{
- flds(MEM_REGION_GVA);
+ uint64_t error_code;
+ uint64_t vector;
+
+ vector = kvm_asm_safe_ec(FLDS_MEM_EAX, error_code, "a"(MEM_REGION_GVA));
+
+ /*
+ * When TDP is disabled, no instruction emulation is required so flds
+ * should generate #PF(RSVD).
+ */
+ if (!tdp_enabled) {
+ GUEST_ASSERT_EQ(vector, PF_VECTOR);
+ GUEST_ASSERT(error_code & PFERR_RSVD_MASK);
+ }
+
GUEST_DONE();
}

@@ -32,6 +45,7 @@ int main(int argc, char *argv[])
struct kvm_vcpu *vcpu;
struct kvm_vm *vm;
uint64_t gpa, pte;
+ struct ucall uc;
uint64_t *hva;
int rc;

@@ -41,6 +55,10 @@ int main(int argc, char *argv[])
TEST_REQUIRE(kvm_has_cap(KVM_CAP_SMALLER_MAXPHYADDR));

vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+ vcpu_args_set(vcpu, 1, kvm_is_tdp_enabled());
+
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vcpu);

vcpu_set_cpuid_maxphyaddr(vcpu, MAXPHYADDR);

@@ -61,10 +79,27 @@ int main(int argc, char *argv[])
vm_set_page_table_entry(vm, vcpu, MEM_REGION_GVA, pte | (1ull << 36));

vcpu_run(vcpu);
- assert_exit_for_flds_emulation_failure(vcpu);
- skip_flds_instruction(vcpu);
- vcpu_run(vcpu);
- ASSERT_EQ(get_ucall(vcpu, NULL), UCALL_DONE);
+
+ /*
+ * When TDP is enabled, KVM must emulate the flds instruction, which
+ * results in an emulation failure out to userspace since KVM does not
+ * know how to emulate flds.
+ */
+ if (kvm_is_tdp_enabled()) {
+ assert_exit_for_flds_emulation_failure(vcpu);
+ skip_flds_instruction(vcpu);
+ vcpu_run(vcpu);
+ }
+
+ switch (get_ucall(vcpu, &uc)) {
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT(uc);
+ break;
+ case UCALL_DONE:
+ break;
+ default:
+ TEST_FAIL("Unrecognized ucall: %lu\n", uc.cmd);
+ }

kvm_vm_free(vm);

--
2.38.1.273.g43a17bfeac-goog