[PATCH v4 09/10] KVM: selftests: Expect #PF(RSVD) when TDP is disabled

[David Matlack <dmatlack@xxxxxxxxxx>]

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@xxxxxxxxxx>
---
 .../smaller_maxphyaddr_emulation_test.c       | 51 +++++++++++++++++--
 1 file changed, 46 insertions(+), 5 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 9d0e555ea630..ea1e7ae37e85 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 +21,28 @@
 #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 enabled, the flds instruction will trigger an emulation
+	 * failure, exit to userspace, and then the selftest skips the
+	 * instruction.
+	 *
+	 * When TDP is disabled, no instruction emulation is required so flds
+	 * should generate #PF(RSVD).
+	 */
+	if (tdp_enabled) {
+		GUEST_ASSERT(!vector);
+	} else {
+		GUEST_ASSERT_EQ(vector, PF_VECTOR);
+		GUEST_ASSERT(error_code & PFERR_RSVD_MASK);
+	}
+
 	GUEST_DONE();
 }
 
@@ -32,6 +51,7 @@ 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 +61,10 @@ 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);
 
@@ -61,9 +85,26 @@ int main(int argc, char *argv[])
 	vm_set_page_table_entry(vm, vcpu, MEM_REGION_GVA, pte | (1ull << 36));
 
 	vcpu_run(vcpu);
-	handle_flds_emulation_failure_exit(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()) {
+		handle_flds_emulation_failure_exit(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