[PATCH V5 5/7] KVM: selftests: add library for creating/interacting with SEV guests

Peter Gonda
2022-10-18T20:59:16Z

Add interfaces to allow tests to create SEV guests. The additional
requirements for SEV guests PTs and other state is encapsulated by the
new vm_sev_create_with_one_vcpu() function. This can future be
generalized for more vCPUs but the first set of SEV selftests in this
series only uses a single vCPU.

Originally-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Peter Gonda <pgonda@google.com>
---
tools/arch/x86/include/asm/kvm_host.h | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/kvm_util_base.h | 15 +-
.../selftests/kvm/include/x86_64/sev.h | 22 ++
tools/testing/selftests/kvm/lib/kvm_util.c | 4 +-
.../selftests/kvm/lib/x86_64/processor.c | 4 +
tools/testing/selftests/kvm/lib/x86_64/sev.c | 243 ++++++++++++++++++
7 files changed, 286 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/kvm/include/x86_64/sev.h
create mode 100644 tools/testing/selftests/kvm/lib/x86_64/sev.c

diff --git a/tools/arch/x86/include/asm/kvm_host.h b/tools/arch/x86/include/asm/kvm_host.h
index 03153c18c747..0357a7135835 100644
--- a/tools/arch/x86/include/asm/kvm_host.h
+++ b/tools/arch/x86/include/asm/kvm_host.h
@@ -9,6 +9,7 @@ struct kvm_vm_arch {
uint64_t pte_me_mask;
uint64_t c_bit;
uint64_t s_bit;
+ bool is_pt_protected;
};

#endif // _TOOLS_LINUX_ASM_X86_KVM_HOST_H
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 65eb45ff1bff..4f27ef70cf2b 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -58,6 +58,7 @@ LIBKVM_x86_64 += lib/x86_64/processor.c
LIBKVM_x86_64 += lib/x86_64/svm.c
LIBKVM_x86_64 += lib/x86_64/ucall.c
LIBKVM_x86_64 += lib/x86_64/vmx.c
+LIBKVM_x86_64 += lib/x86_64/sev.c

LIBKVM_aarch64 += lib/aarch64/gic.c
LIBKVM_aarch64 += lib/aarch64/gic_v3.c
diff --git a/tools/testing/selftests/kvm/include/kvm_util_base.h b/tools/testing/selftests/kvm/include/kvm_util_base.h
index 4224026fbe25..8e4ded757a40 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -68,6 +68,13 @@ struct userspace_mem_regions {
DECLARE_HASHTABLE(slot_hash, 9);
};

+/* VM protection policy/configuration. */
+struct protected_vm {
+ bool enabled;
+ bool has_protected_bit;
+ int8_t protected_bit;
+};
+
struct kvm_vm {
int mode;
unsigned long type;
@@ -670,6 +677,10 @@ static inline vm_paddr_t vm_phy_pages_alloc(struct kvm_vm *vm, size_t num,
return _vm_phy_pages_alloc(vm, num, paddr_min, memslot, vm->protected);
}

+uint64_t vm_nr_pages_required(enum vm_guest_mode mode,
+ uint32_t nr_runnable_vcpus,
+ uint64_t extra_mem_pages);
+
/*
* ____vm_create() does KVM_CREATE_VM and little else. __vm_create() also
* loads the test binary into guest memory and creates an IRQ chip (x86 only).
@@ -722,8 +733,8 @@ unsigned long vm_compute_max_gfn(struct kvm_vm *vm);
unsigned int vm_calc_num_guest_pages(enum vm_guest_mode mode, size_t size);
unsigned int vm_num_host_pages(enum vm_guest_mode mode, unsigned int num_guest_pages);
unsigned int vm_num_guest_pages(enum vm_guest_mode mode, unsigned int num_host_pages);
-static inline unsigned int
-vm_adjust_num_guest_pages(enum vm_guest_mode mode, unsigned int num_guest_pages)
+static inline unsigned int vm_adjust_num_guest_pages(enum vm_guest_mode mode,
+ unsigned int num_guest_pages)
{
unsigned int n;
n = vm_num_guest_pages(mode, vm_num_host_pages(mode, num_guest_pages));
diff --git a/tools/testing/selftests/kvm/include/x86_64/sev.h b/tools/testing/selftests/kvm/include/x86_64/sev.h
new file mode 100644
index 000000000000..1148db928d0b
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/x86_64/sev.h
@@ -0,0 +1,22 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Helpers used for SEV guests
+ *
+ */
+#ifndef SELFTEST_KVM_SEV_H
+#define SELFTEST_KVM_SEV_H
+
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "kvm_util.h"
+
+#define SEV_POLICY_NO_DBG (1UL << 0)
+#define SEV_POLICY_ES (1UL << 2)
+
+bool is_kvm_sev_supported(void);
+
+struct kvm_vm *vm_sev_create_with_one_vcpu(uint32_t policy, void *guest_code,
+ struct kvm_vcpu **cpu);
+
+#endif /* SELFTEST_KVM_SEV_H */
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index d753345993d6..753b8991eff3 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -254,7 +254,7 @@ struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages)
vm->pgtable_levels = 4;
vm->va_bits = 48;
#else
- TEST_FAIL("VM_MODE_PXXV48_4K not supported on non-x86 platforms");
+ TEST_FAIL("VM_MODE_PXXV48_4K* not supported on non-x86 platforms");
#endif
break;
case VM_MODE_P47V64_4K:
@@ -294,7 +294,7 @@ struct kvm_vm *____vm_create(enum vm_guest_mode mode, uint64_t nr_pages)
return vm;
}

-static uint64_t vm_nr_pages_required(enum vm_guest_mode mode,
+uint64_t vm_nr_pages_required(enum vm_guest_mode mode,
uint32_t nr_runnable_vcpus,
uint64_t extra_mem_pages)
{
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index 377e342ecff7..04a5434ba3dd 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -529,6 +529,10 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
uint64_t *pml4e, *pdpe, *pde;
uint64_t *pte;

+ TEST_ASSERT(
+ !vm->arch.is_pt_protected,
+ "Protected guests have their page tables protected so gva2gpa conversions are not possible.");
+
TEST_ASSERT(vm->mode == VM_MODE_PXXV48_4K, "Attempt to use "
"unknown or unsupported guest mode, mode: 0x%x", vm->mode);

diff --git a/tools/testing/selftests/kvm/lib/x86_64/sev.c b/tools/testing/selftests/kvm/lib/x86_64/sev.c
new file mode 100644
index 000000000000..faed2ebe63ac
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/x86_64/sev.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Helpers used for SEV guests
+ *
+ */
+
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <stdint.h>
+#include <stdbool.h>
+
+#include "kvm_util.h"
+#include "svm_util.h"
+#include "linux/psp-sev.h"
+#include "processor.h"
+#include "sev.h"
+
+#define CPUID_MEM_ENC_LEAF 0x8000001f
+#define CPUID_EBX_CBIT_MASK 0x3f
+
+#define SEV_FW_REQ_VER_MAJOR 0
+#define SEV_FW_REQ_VER_MINOR 17
+
+enum sev_guest_state {
+ SEV_GSTATE_UNINIT = 0,
+ SEV_GSTATE_LUPDATE,
+ SEV_GSTATE_LSECRET,
+ SEV_GSTATE_RUNNING,
+};
+
+static void sev_ioctl(int cmd, void *data)
+{
+ int ret;
+ struct sev_issue_cmd arg;
+
+ arg.cmd = cmd;
+ arg.data = (unsigned long)data;
+ ret = ioctl(open_sev_dev_path_or_exit(), SEV_ISSUE_CMD, &arg);
+ TEST_ASSERT(ret == 0, "SEV ioctl %d failed, error: %d, fw_error: %d",
+ cmd, ret, arg.error);
+}
+
+static void kvm_sev_ioctl(struct kvm_vm *vm, int cmd, void *data)
+{
+ struct kvm_sev_cmd arg = {0};
+ int ret;
+
+ arg.id = cmd;
+ arg.sev_fd = open_sev_dev_path_or_exit();
+ arg.data = (__u64)data;
+
+ ret = ioctl(vm->fd, KVM_MEMORY_ENCRYPT_OP, &arg);
+ TEST_ASSERT(
+ ret == 0,
+ "SEV KVM ioctl %d failed, rc: %i errno: %i (%s), fw_error: %d",
+ cmd, ret, errno, strerror(errno), arg.error);
+}
+
+static void sev_register_user_region(struct kvm_vm *vm, struct userspace_mem_region *region)
+{
+ struct kvm_enc_region range = {0};
+ int ret;
+
+ range.addr = (__u64)region->region.userspace_addr;
+ ;
+ range.size = region->region.memory_size;
+
+ ret = ioctl(vm->fd, KVM_MEMORY_ENCRYPT_REG_REGION, &range);
+ TEST_ASSERT(ret == 0, "failed to register user range, errno: %i\n",
+ errno);
+}
+
+static void sev_launch_update_data(struct kvm_vm *vm, vm_paddr_t gpa, uint64_t size)
+{
+ struct kvm_sev_launch_update_data ksev_update_data = {0};
+
+ pr_debug("%s: addr: 0x%lx, size: %lu\n", __func__, gpa, size);
+
+ ksev_update_data.uaddr = (__u64)addr_gpa2hva(vm, gpa);
+ ksev_update_data.len = size;
+
+ kvm_sev_ioctl(vm, KVM_SEV_LAUNCH_UPDATE_DATA, &ksev_update_data);
+}
+
+static void encrypt_region(struct kvm_vm *vm, struct userspace_mem_region *region)
+{
+ const struct sparsebit *protected_phy_pages =
+ region->protected_phy_pages;
+ const uint64_t memory_size = region->region.memory_size;
+ const vm_paddr_t gpa_start = region->region.guest_phys_addr;
+ sparsebit_idx_t pg = 0;
+
+ sev_register_user_region(vm, region);
+
+ while (pg < (memory_size / vm->page_size)) {
+ sparsebit_idx_t nr_pages;
+
+ if (sparsebit_is_clear(protected_phy_pages, pg)) {
+ pg = sparsebit_next_set(protected_phy_pages, pg);
+ if (!pg)
+ break;
+ }
+
+ nr_pages = sparsebit_next_clear(protected_phy_pages, pg) - pg;
+ if (nr_pages <= 0)
+ nr_pages = 1;
+
+ sev_launch_update_data(vm, gpa_start + pg * vm->page_size,
+ nr_pages * vm->page_size);
+ pg += nr_pages;
+ }
+}
+
+static void sev_encrypt(struct kvm_vm *vm)
+{
+ int ctr;
+ struct userspace_mem_region *region;
+
+ hash_for_each(vm->regions.slot_hash, ctr, region, slot_node) {
+ encrypt_region(vm, region);
+ }
+
+ vm->arch.is_pt_protected = true;
+}
+
+bool is_kvm_sev_supported(void)
+{
+ struct sev_user_data_status sev_status;
+
+ sev_ioctl(SEV_PLATFORM_STATUS, &sev_status);
+
+ if (!(sev_status.api_major > SEV_FW_REQ_VER_MAJOR ||
+ (sev_status.api_major == SEV_FW_REQ_VER_MAJOR &&
+ sev_status.api_minor >= SEV_FW_REQ_VER_MINOR))) {
+ pr_info("SEV FW version too old. Have API %d.%d (build: %d), need %d.%d, skipping test.\n",
+ sev_status.api_major, sev_status.api_minor,
+ sev_status.build, SEV_FW_REQ_VER_MAJOR,
+ SEV_FW_REQ_VER_MINOR);
+ return false;
+ }
+
+ return true;
+}
+
+static void sev_vm_launch(struct kvm_vm *vm, uint32_t policy)
+{
+ struct kvm_sev_launch_start ksev_launch_start = {0};
+ struct kvm_sev_guest_status ksev_status;
+
+ ksev_launch_start.policy = policy;
+ kvm_sev_ioctl(vm, KVM_SEV_LAUNCH_START, &ksev_launch_start);
+ kvm_sev_ioctl(vm, KVM_SEV_GUEST_STATUS, &ksev_status);
+ TEST_ASSERT(ksev_status.policy == policy, "Incorrect guest policy.");
+ TEST_ASSERT(ksev_status.state == SEV_GSTATE_LUPDATE,
+ "Unexpected guest state: %d", ksev_status.state);
+
+ ucall_init(vm, 0);
+
+ sev_encrypt(vm);
+}
+
+static void sev_vm_launch_measure(struct kvm_vm *vm, uint8_t *measurement)
+{
+ struct kvm_sev_launch_measure ksev_launch_measure;
+ struct kvm_sev_guest_status ksev_guest_status;
+
+ ksev_launch_measure.len = 256;
+ ksev_launch_measure.uaddr = (__u64)measurement;
+ kvm_sev_ioctl(vm, KVM_SEV_LAUNCH_MEASURE, &ksev_launch_measure);
+
+ kvm_sev_ioctl(vm, KVM_SEV_GUEST_STATUS, &ksev_guest_status);
+ TEST_ASSERT(ksev_guest_status.state == SEV_GSTATE_LSECRET,
+ "Unexpected guest state: %d", ksev_guest_status.state);
+}
+
+static void sev_vm_launch_finish(struct kvm_vm *vm)
+{
+ struct kvm_sev_guest_status ksev_status;
+
+ kvm_sev_ioctl(vm, KVM_SEV_GUEST_STATUS, &ksev_status);
+ TEST_ASSERT(ksev_status.state == SEV_GSTATE_LUPDATE ||
+ ksev_status.state == SEV_GSTATE_LSECRET,
+ "Unexpected guest state: %d", ksev_status.state);
+
+ kvm_sev_ioctl(vm, KVM_SEV_LAUNCH_FINISH, NULL);
+
+ kvm_sev_ioctl(vm, KVM_SEV_GUEST_STATUS, &ksev_status);
+ TEST_ASSERT(ksev_status.state == SEV_GSTATE_RUNNING,
+ "Unexpected guest state: %d", ksev_status.state);
+}
+
+static void configure_sev_pte_masks(struct kvm_vm *vm)
+{
+ uint32_t eax, ebx, ecx, edx, enc_bit;
+
+ cpuid(CPUID_MEM_ENC_LEAF, &eax, &ebx, &ecx, &edx);
+ enc_bit = ebx & CPUID_EBX_CBIT_MASK;
+
+ vm->arch.c_bit = 1 << enc_bit;
+ vm->arch.pte_me_mask = vm->arch.c_bit | vm->arch.s_bit;
+ vm->protected = true;
+}
+
+static void sev_vm_measure(struct kvm_vm *vm)
+{
+ uint8_t measurement[512];
+ int i;
+
+ sev_vm_launch_measure(vm, measurement);
+
+ /* TODO: Validate the measurement is as expected. */
+ pr_debug("guest measurement: ");
+ for (i = 0; i < 32; ++i)
+ pr_debug("%02x", measurement[i]);
+ pr_debug("\n");
+}
+
+struct kvm_vm *vm_sev_create_with_one_vcpu(uint32_t policy, void *guest_code,
+ struct kvm_vcpu **cpu)
+{
+ enum vm_guest_mode mode = VM_MODE_PXXV48_4K;
+ uint64_t nr_pages = vm_nr_pages_required(mode, 1, 0);
+ struct kvm_vm *vm;
+
+ vm = ____vm_create(mode, nr_pages);
+
+ kvm_sev_ioctl(vm, KVM_SEV_INIT, NULL);
+
+ configure_sev_pte_masks(vm);
+
+ *cpu = vm_vcpu_add(vm, 0, guest_code);
+ kvm_vm_elf_load(vm, program_invocation_name);
+
+ sev_vm_launch(vm, policy);
+
+ sev_vm_measure(vm);
+
+ sev_vm_launch_finish(vm);
+
+ pr_info("SEV guest created, policy: 0x%x, size: %lu KB\n", policy,
+ nr_pages * vm->page_size / 1024);
+
+ return vm;
+}
--
2.38.0.413.g74048e4d9e-goog