From: Michael Roth <michael.roth@xxxxxxx>
SEV, SEV-ES, and SNP have a few corner cases where there is potential
for KVM_PRE_FAULT_MEMORY to behave differently depending on when it is
issued during initial guest setup. Exercising these various paths
requires a bit more fine-grained control over when the
KVM_PRE_FAULT_MEMORY requests are issued while setting up the guests.
Since these CoCo-specific events are likely to be architecture-specific
KST helpers, take the existing generic test in pre_fault_memory_test.c
as a starting template, and then introduce an x86-specific version of
it with expanded coverage for SEV, SEV-ES, and SNP.
Since there's a reasonable chance that TDX could extend this for similar
testing of TDX, give it a "coco-" prefix rather than an SEV-specific
one.
Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
Co-developed-by: Pratik R. Sampat <pratikrajesh.sampat@xxxxxxx>
Signed-off-by: Pratik R. Sampat <pratikrajesh.sampat@xxxxxxx>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../kvm/x86_64/coco_pre_fault_memory_test.c | 314 ++++++++++++++++++
2 files changed, 315 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 48d32c5aa3eb..65d19b277b06 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -129,6 +129,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/amx_test
TEST_GEN_PROGS_x86_64 += x86_64/max_vcpuid_cap_test
TEST_GEN_PROGS_x86_64 += x86_64/triple_fault_event_test
TEST_GEN_PROGS_x86_64 += x86_64/recalc_apic_map_test
+TEST_GEN_PROGS_x86_64 += x86_64/coco_pre_fault_memory_test
TEST_GEN_PROGS_x86_64 += access_tracking_perf_test
TEST_GEN_PROGS_x86_64 += demand_paging_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
diff --git a/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
new file mode 100644
index 000000000000..e16fe185fb5a
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/coco_pre_fault_memory_test.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/sizes.h>
+
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+#include "sev.h"
+
+/* Arbitrarily chosen values */
+#define TEST_SIZE (SZ_2M + PAGE_SIZE)
+#define TEST_NPAGES (TEST_SIZE / PAGE_SIZE)
+#define TEST_SLOT 10
+#define TEST_GPA 0x100000000ul
+#define TEST_GVA 0x100000000ul
+
+enum prefault_snp_test_type {
+ /* Skip pre-faulting tests. */
+ NO_PREFAULT_TYPE = 0,
+ /*
+ * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping non-private memory
+ * before finalizing the initial guest contents (e.g. via
+ * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
+ *
+ * This should result in failure since KVM explicitly disallows
+ * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
+ * initial guest contents.
+ */
+ PREFAULT_SHARED_BEFORE_FINALIZING = 0,
+ /*
+ * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping private memory
+ * before finalizing the initial guest contents (e.g. via
+ * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
+ *
+ * This should result in failure since KVM explicitly disallows
+ * KVM_PRE_FAULT_MEMORY from being issued prior to finalizing the
+ * initial guest contents.
+ */
+ PREFAULT_PRIVATE_BEFORE_FINALIZING,
+ /*
+ * Issue KVM_PRE_FAULT_MEMORY for GFNs mapping shared/private
+ * memory after finalizing the initial guest contents
+ * (e.g. via * KVM_SEV_SNP_LAUNCH_FINISH for SNP guests).
+ *
+ * This should succeed since pre-faulting is supported for both
+ * non-private/private memory once the guest contents are finalized.
+ */
+ PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING
+};
+
+static void guest_code_sev(void)
+{
+ int i;
+
+ GUEST_ASSERT(rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ENABLED);
+
+ for (i = 0; i < TEST_NPAGES; i++) {
+ uint64_t *src = (uint64_t *)(TEST_GVA + i * PAGE_SIZE);
+ uint64_t val = *src;
+
+ /* Validate the data stored in the pages */
+ if ((i < TEST_NPAGES / 2 && val != i + 1) ||
+ (i >= TEST_NPAGES / 2 && val != 0)) {
+ GUEST_FAIL("Inconsistent view of memory values in guest");
+ }
+ }
+
+ if (rdmsr(MSR_AMD64_SEV) & MSR_AMD64_SEV_ES_ENABLED) {
+ wrmsr(MSR_AMD64_SEV_ES_GHCB, GHCB_MSR_TERM_REQ);
+ __asm__ __volatile__("rep; vmmcall");
+ GUEST_FAIL("This should be unreachable.");
+ }
+
+ GUEST_DONE();
+}
+
+static void __pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa, u64 size,
+ u64 left, bool expect_fail)
+{
+ struct kvm_pre_fault_memory range = {
+ .gpa = gpa,
+ .size = size,
+ .flags = 0,
+ };
+ int ret, save_errno;
+ u64 prev;
+
+ do {
+ prev = range.size;
+ ret = __vcpu_ioctl(vcpu, KVM_PRE_FAULT_MEMORY, &range);
+ save_errno = errno;
+ TEST_ASSERT((range.size < prev) ^ (ret < 0),
+ "%sexpecting range.size to change on %s",
+ ret < 0 ? "not " : "",
+ ret < 0 ? "failure" : "success");
+ } while (ret >= 0 ? range.size : save_errno == EINTR);
+
+ TEST_ASSERT(expect_fail ? !(range.size == left) : (range.size == left),
+ "[EXPECT %s] completed with %lld bytes left, expected %" PRId64,
+ expect_fail ? "FAIL" : "PASS",
+ range.size, left);
+
+ if (left == 0) {
+ TEST_ASSERT(expect_fail ? ret : !ret,
+ "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
+ expect_fail ? "FAIL" : "PASS");
+ } else {
+ /*
+ * For shared memory, no memory slot causes RET_PF_EMULATE. It
+ * results in -ENOENT.
+ *
+ * For private memory, no memory slot is an error case returning
+ * -EFAULT, but it also possible the only the GPA ranges backed
+ * by a slot are marked as private, in which case the noslot
+ * range will also result in -ENOENT.
+ *
+ * So allow both errors for now, but in the future it would be
+ * good to distinguish between these cases to tighten up the
+ * error-checking.
+ */
+ TEST_ASSERT(expect_fail ? !ret :
+ (ret && (save_errno == EFAULT || save_errno == ENOENT)),
+ "[EXPECT %s] KVM_PRE_FAULT_MEMORY",
+ expect_fail ? "FAIL" : "PASS");
+ }
+}
+
+static void pre_fault_memory(struct kvm_vcpu *vcpu, u64 gpa,
+ u64 size, u64 left)
+{
+ __pre_fault_memory(vcpu, gpa, size, left, false);
+}
+
+static void pre_fault_memory_negative(struct kvm_vcpu *vcpu, u64 gpa,
+ u64 size, u64 left)
+{
+ __pre_fault_memory(vcpu, gpa, size, left, true);
+}
+
+static void pre_fault_memory_snp(struct kvm_vcpu *vcpu, struct kvm_vm *vm,
+ bool private, enum prefault_snp_test_type p_type)
+{
+ if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+ pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+
+ snp_vm_launch_start(vm, SNP_POLICY);
+
+ if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+ pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+
+ if (private) {
+ /*
+ * Make sure when pages are pre-faulted later after
+ * finalization they are treated the same as a private
+ * access by the guest so that the expected gmem
+ * backing pages are used.
+ */
+ vm_mem_set_private(vm, TEST_GPA, TEST_SIZE);
+ if (p_type == PREFAULT_PRIVATE_BEFORE_FINALIZING)
+ pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+ } else {
+ if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+ pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+ }
+
+ snp_vm_launch_update(vm);
+
+ if (p_type == PREFAULT_SHARED_BEFORE_FINALIZING)
+ pre_fault_memory_negative(vcpu, TEST_GPA, SZ_2M, 0);
+
+ snp_vm_launch_finish(vm);
+
+ /*
+ * After finalization, pre-faulting either private or shared
+ * ranges should work regardless of whether the pages were
+ * encrypted as part of setting up initial guest state.
+ */
+ if (p_type == PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING) {
+ pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+ pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+ pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+ }
+}
+
+static void pre_fault_memory_sev(unsigned long vm_type, struct kvm_vcpu *vcpu,
+ struct kvm_vm *vm)
+{
+ uint32_t policy = (vm_type == KVM_X86_SEV_ES_VM) ? SEV_POLICY_ES : 0;
+
+ pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+ pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+ pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+
+ sev_vm_launch(vm, policy);
+
+ pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+ pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+ pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+
+ sev_vm_launch_measure(vm, alloca(256));
+
+ pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+ pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+ pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+
+ sev_vm_launch_finish(vm);
+
+ pre_fault_memory(vcpu, TEST_GPA, SZ_2M, 0);
+ pre_fault_memory(vcpu, TEST_GPA + SZ_2M, PAGE_SIZE * 2, PAGE_SIZE);
+ pre_fault_memory(vcpu, TEST_GPA + TEST_SIZE, PAGE_SIZE, PAGE_SIZE);
+}
+
+static void test_pre_fault_memory_sev(unsigned long vm_type, bool private,
+ enum prefault_snp_test_type p_type)
+{
+ struct kvm_vcpu *vcpu;
+ struct kvm_vm *vm;
+ struct ucall uc;
+ int i;
+
+ vm = vm_sev_create_with_one_vcpu(vm_type, guest_code_sev, &vcpu);
+
+ vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
+ TEST_GPA, TEST_SLOT, TEST_NPAGES,
+ (vm_type == KVM_X86_SNP_VM) ? KVM_MEM_GUEST_MEMFD : 0);
+
+ /*
+ * Make sure guest page table is in agreement with what pages will be
+ * initially encrypted by the ASP.
+ */
+ if (private)
+ vm_mem_set_protected(vm, TEST_SLOT, TEST_GPA, TEST_NPAGES);
+
+ virt_map(vm, TEST_GVA, TEST_GPA, TEST_NPAGES);
+
+ /*
+ * Populate the pages to compare data read from the guest
+ * Populate the first half with data and second half as all zeros.
+ */
+ for (i = 0; i < TEST_NPAGES; i++) {
+ uint64_t *hva = addr_gva2hva(vm, TEST_GVA + i * PAGE_SIZE);
+
+ if (i < TEST_NPAGES / 2)
+ *hva = i + 1;
+ else
+ *hva = 0;
+ }
+
+ if (vm_type == KVM_X86_SNP_VM)
+ pre_fault_memory_snp(vcpu, vm, private, p_type);
+ else
+ pre_fault_memory_sev(vm_type, vcpu, vm);
+
+ vcpu_run(vcpu);
+
+ if (vm->type == KVM_X86_SEV_ES_VM || vm->type == KVM_X86_SNP_VM) {
+ TEST_ASSERT(vcpu->run->exit_reason == KVM_EXIT_SYSTEM_EVENT,
+ "Wanted SYSTEM_EVENT, got %s",
+ exit_reason_str(vcpu->run->exit_reason));
+ TEST_ASSERT_EQ(vcpu->run->system_event.type, KVM_SYSTEM_EVENT_SEV_TERM);
+ TEST_ASSERT_EQ(vcpu->run->system_event.ndata, 1);
+ TEST_ASSERT_EQ(vcpu->run->system_event.data[0], GHCB_MSR_TERM_REQ);
+ goto out;
+ }
+
+ switch (get_ucall(vcpu, &uc)) {
+ case UCALL_DONE:
+ break;
+ case UCALL_ABORT:
+ REPORT_GUEST_ASSERT(uc);
+ default:
+ TEST_FAIL("Unexpected exit: %s",
+ exit_reason_str(vcpu->run->exit_reason));
+ }
+
+out:
+ kvm_vm_free(vm);
+}
+
+static void test_pre_fault_memory(unsigned long vm_type, bool private)
+{
+ int pt;
+
+ if (vm_type && !(kvm_check_cap(KVM_CAP_VM_TYPES) & BIT(vm_type))) {
+ pr_info("Skipping tests for vm_type 0x%lx\n", vm_type);
+ return;
+ }
+
+ switch (vm_type) {
+ case KVM_X86_SEV_VM:
+ case KVM_X86_SEV_ES_VM:
+ test_pre_fault_memory_sev(vm_type, private, NO_PREFAULT_TYPE);
+ break;
+ case KVM_X86_SNP_VM:
+ for (pt = 0; pt <= PREFAULT_PRIVATE_SHARED_AFTER_FINALIZING; pt++)
+ test_pre_fault_memory_sev(vm_type, private, pt);
+ break;
+ default:
+ abort();
+ }
+}
+
+int main(int argc, char *argv[])
+{
+ TEST_REQUIRE(kvm_check_cap(KVM_CAP_PRE_FAULT_MEMORY));
+
+ test_pre_fault_memory(KVM_X86_SEV_VM, false);
+ test_pre_fault_memory(KVM_X86_SEV_VM, true);
+ test_pre_fault_memory(KVM_X86_SEV_ES_VM, false);
+ test_pre_fault_memory(KVM_X86_SEV_ES_VM, true);
+ test_pre_fault_memory(KVM_X86_SNP_VM, false);
+ test_pre_fault_memory(KVM_X86_SNP_VM, true);
+
+ return 0;
+}
