KVM: selftests: Expect #PF(RSVD) when TDP is disabled

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>
Link: https://lore.kernel.org/r/20221102184654.282799-10-dmatlack@google.com
[sean: massage comment to talk about having to emulate due to MAXPHYADDR]
Signed-off-by: Sean Christopherson <seanjc@google.com>

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 a8d0811..06edf00 100644 (file)
--- 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 +21,27 @@
 #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, flds will trigger an emulation failure, exit to
+        * userspace, and then the selftest host "VMM" 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();
 }
 
@@ -31,6 +49,7 @@ int main(int argc, char *argv[])
 {
        struct kvm_vcpu *vcpu;
        struct kvm_vm *vm;
+       struct ucall uc;
        uint64_t *pte;
        uint64_t *hva;
        uint64_t gpa;
@@ -39,6 +58,10 @@ 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);
 
@@ -60,9 +83,27 @@ int main(int argc, char *argv[])
        *pte |= BIT_ULL(MAXPHYADDR);
 
        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 in response the guest physical
+        * address that is illegal from the guest's perspective, but is legal
+        * from hardware's perspeective.  This should result in an emulation
+        * failure exit to userspace since KVM doesn't support emulating 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);