From: Michael Roth michael.roth@amd.com
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@amd.com Co-developed-by: Pratik R. Sampat pratikrajesh.sampat@amd.com Signed-off-by: Pratik R. Sampat pratikrajesh.sampat@amd.com Tested-by: Peter Gonda pgonda@google.com Tested-by: Srikanth Aithal sraithal@amd.com --- 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 45cb70c048bb..7b97750a7d71 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 += coalesced_io_test TEST_GEN_PROGS_x86_64 += demand_paging_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..c31a5f9e18f4 --- /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, + /* + * 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, + /* + * 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. However, it is also possible that 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 consistency in the guest + * Fill the first half with data and second half with 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; +}