KVM: selftests: Test KVM exit behavior for private memory/access

"Testing private access when memslot gets deleted" tests the behavior
of KVM when a private memslot gets deleted while the VM is using the
private memslot. When KVM looks up the deleted (slot = NULL) memslot,
KVM should exit to userspace with KVM_EXIT_MEMORY_FAULT.

In the second test, upon a private access to non-private memslot, KVM
should also exit to userspace with KVM_EXIT_MEMORY_FAULT.

Intentionally don't take a requirement on KVM_CAP_GUEST_MEMFD,
KVM_CAP_MEMORY_FAULT_INFO, KVM_MEMORY_ATTRIBUTE_PRIVATE, etc., as it's a
KVM bug to advertise KVM_X86_SW_PROTECTED_VM without its prerequisites.

Signed-off-by: Ackerley Tng <ackerleytng@google.com>
[sean: call out the similarities with set_memory_region_test]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20231027182217.3615211-36-seanjc@google.com>
Reviewed-by: Fuad Tabba <tabba@google.com>
Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index fd3b30a4ca7bb51174cb551287c580e0fb77f019..69ce8e06b3a34e6548b5a1a0705e0dd010713f70 100644 (file)
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -92,6 +92,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/nested_exceptions_test
 TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
 TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test
 TEST_GEN_PROGS_x86_64 += x86_64/private_mem_conversions_test
+TEST_GEN_PROGS_x86_64 += x86_64/private_mem_kvm_exits_test
 TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id
 TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
 TEST_GEN_PROGS_x86_64 += x86_64/smaller_maxphyaddr_emulation_test

diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c b/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
new file mode 100644 (file)
index 0000000..13e72fc
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/private_mem_kvm_exits_test.c
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2023, Google LLC.
+ */
+#include <linux/kvm.h>
+#include <pthread.h>
+#include <stdint.h>
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "test_util.h"
+
+/* Arbitrarily selected to avoid overlaps with anything else */
+#define EXITS_TEST_GVA 0xc0000000
+#define EXITS_TEST_GPA EXITS_TEST_GVA
+#define EXITS_TEST_NPAGES 1
+#define EXITS_TEST_SIZE (EXITS_TEST_NPAGES * PAGE_SIZE)
+#define EXITS_TEST_SLOT 10
+
+static uint64_t guest_repeatedly_read(void)
+{
+       volatile uint64_t value;
+
+       while (true)
+               value = *((uint64_t *) EXITS_TEST_GVA);
+
+       return value;
+}
+
+static uint32_t run_vcpu_get_exit_reason(struct kvm_vcpu *vcpu)
+{
+       int r;
+
+       r = _vcpu_run(vcpu);
+       if (r) {
+               TEST_ASSERT(errno == EFAULT, KVM_IOCTL_ERROR(KVM_RUN, r));
+               TEST_ASSERT_EQ(vcpu->run->exit_reason, KVM_EXIT_MEMORY_FAULT);
+       }
+       return vcpu->run->exit_reason;
+}
+
+const struct vm_shape protected_vm_shape = {
+       .mode = VM_MODE_DEFAULT,
+       .type = KVM_X86_SW_PROTECTED_VM,
+};
+
+static void test_private_access_memslot_deleted(void)
+{
+       struct kvm_vm *vm;
+       struct kvm_vcpu *vcpu;
+       pthread_t vm_thread;
+       void *thread_return;
+       uint32_t exit_reason;
+
+       vm = vm_create_shape_with_one_vcpu(protected_vm_shape, &vcpu,
+                                          guest_repeatedly_read);
+
+       vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+                                   EXITS_TEST_GPA, EXITS_TEST_SLOT,
+                                   EXITS_TEST_NPAGES,
+                                   KVM_MEM_GUEST_MEMFD);
+
+       virt_map(vm, EXITS_TEST_GVA, EXITS_TEST_GPA, EXITS_TEST_NPAGES);
+
+       /* Request to access page privately */
+       vm_mem_set_private(vm, EXITS_TEST_GPA, EXITS_TEST_SIZE);
+
+       pthread_create(&vm_thread, NULL,
+                      (void *(*)(void *))run_vcpu_get_exit_reason,
+                      (void *)vcpu);
+
+       vm_mem_region_delete(vm, EXITS_TEST_SLOT);
+
+       pthread_join(vm_thread, &thread_return);
+       exit_reason = (uint32_t)(uint64_t)thread_return;
+
+       TEST_ASSERT_EQ(exit_reason, KVM_EXIT_MEMORY_FAULT);
+       TEST_ASSERT_EQ(vcpu->run->memory_fault.flags, KVM_MEMORY_EXIT_FLAG_PRIVATE);
+       TEST_ASSERT_EQ(vcpu->run->memory_fault.gpa, EXITS_TEST_GPA);
+       TEST_ASSERT_EQ(vcpu->run->memory_fault.size, EXITS_TEST_SIZE);
+
+       kvm_vm_free(vm);
+}
+
+static void test_private_access_memslot_not_private(void)
+{
+       struct kvm_vm *vm;
+       struct kvm_vcpu *vcpu;
+       uint32_t exit_reason;
+
+       vm = vm_create_shape_with_one_vcpu(protected_vm_shape, &vcpu,
+                                          guest_repeatedly_read);
+
+       /* Add a non-private memslot (flags = 0) */
+       vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+                                   EXITS_TEST_GPA, EXITS_TEST_SLOT,
+                                   EXITS_TEST_NPAGES, 0);
+
+       virt_map(vm, EXITS_TEST_GVA, EXITS_TEST_GPA, EXITS_TEST_NPAGES);
+
+       /* Request to access page privately */
+       vm_mem_set_private(vm, EXITS_TEST_GPA, EXITS_TEST_SIZE);
+
+       exit_reason = run_vcpu_get_exit_reason(vcpu);
+
+       TEST_ASSERT_EQ(exit_reason, KVM_EXIT_MEMORY_FAULT);
+       TEST_ASSERT_EQ(vcpu->run->memory_fault.flags, KVM_MEMORY_EXIT_FLAG_PRIVATE);
+       TEST_ASSERT_EQ(vcpu->run->memory_fault.gpa, EXITS_TEST_GPA);
+       TEST_ASSERT_EQ(vcpu->run->memory_fault.size, EXITS_TEST_SIZE);
+
+       kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+       TEST_REQUIRE(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(KVM_X86_SW_PROTECTED_VM));
+
+       test_private_access_memslot_deleted();
+       test_private_access_memslot_not_private();
+}