[PATCH v2 7/8] 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       | 45 +++++++++++++++++--
 1 file changed, 41 insertions(+), 4 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 91a85a00b692..afa9e0b3dd8a 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
@@ -21,6 +21,12 @@
 #define MEM_REGION_SLOT	10
 #define MEM_REGION_SIZE PAGE_SIZE
 
+static void guest_page_fault_handler(struct ex_regs *regs)
+{
+	GUEST_ASSERT(regs->error_code & PFERR_RSVD_MASK);
+	GUEST_SYNC(PF_VECTOR);
+}
+
 static void guest_code(void)
 {
 	flds(MEM_REGION_GVA);
@@ -36,6 +42,23 @@ static void assert_ucall_done(struct kvm_vcpu *vcpu)
 		    uc.cmd, UCALL_DONE);
 }
 
+static void assert_reserved_page_fault(struct kvm_vcpu *vcpu)
+{
+	struct ucall uc;
+
+	switch (get_ucall(vcpu, &uc)) {
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+		break;
+	case UCALL_SYNC:
+		TEST_ASSERT(uc.args[1] == PF_VECTOR,
+			    "Unexpected UCALL_SYNC: %lu", uc.args[1]);
+		break;
+	default:
+		TEST_FAIL("Unrecognized ucall: %lu\n", uc.cmd);
+	}
+}
+
 int main(int argc, char *argv[])
 {
 	struct kvm_vcpu *vcpu;
@@ -50,6 +73,9 @@ int main(int argc, char *argv[])
 	TEST_REQUIRE(kvm_has_cap(KVM_CAP_SMALLER_MAXPHYADDR));
 
 	vm = vm_create_with_one_vcpu(&vcpu, guest_code);
+	vm_init_descriptor_tables(vm);
+	vcpu_init_descriptor_tables(vcpu);
+	vm_install_exception_handler(vm, PF_VECTOR, guest_page_fault_handler);
 
 	vcpu_set_cpuid_maxphyaddr(vcpu, MAXPHYADDR);
 
@@ -70,10 +96,21 @@ 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_ucall_done(vcpu);
+
+	/*
+	 * When TDP is enabled, KVM must emulate the flds instruction, which
+	 * results in an emulation failure out to userspace. Otherwise, no
+	 * instruction emulation is required so check that the instruction
+	 * generates #PF(RSVD).
+	 */
+	if (kvm_is_tdp_enabled()) {
+		assert_exit_for_flds_emulation_failure(vcpu);
+		skip_flds_instruction(vcpu);
+		vcpu_run(vcpu);
+		assert_ucall_done(vcpu);
+	} else {
+		assert_reserved_page_fault(vcpu);
+	}
 
 	kvm_vm_free(vm);
 
-- 
2.38.0.413.g74048e4d9e-goog