[V3 08/11] KVM: selftests: add library for creating/interacting with SEV guests

Peter Gonda
2022-08-10T15:21:52Z

From: Michael Roth <michael.roth@amd.com>

Add interfaces to allow tests to create/manage SEV guests. The
additional state associated with these guests is encapsulated in a new
struct sev_vm, which is a light wrapper around struct kvm_vm. These
VMs will use vm_set_memory_encryption() and vm_get_encrypted_phy_pages()
under the covers to configure and sync up with the core kvm_util
library on what should/shouldn't be treated as encrypted memory.

Signed-off-by: Michael Roth <michael.roth@amd.com>
Signed-off-by: Peter Gonda <pgonda@google.com>
---
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/kvm_util_base.h | 3 +
.../selftests/kvm/include/x86_64/sev.h | 44 +++
tools/testing/selftests/kvm/lib/x86_64/sev.c | 251 ++++++++++++++++++
4 files changed, 299 insertions(+)
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/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 39fc5e8e5594..b247c4b595af 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -55,6 +55,7 @@ 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 8ce9e5be70a3..1a84d2d1d85b 100644
--- a/tools/testing/selftests/kvm/include/kvm_util_base.h
+++ b/tools/testing/selftests/kvm/include/kvm_util_base.h
@@ -68,6 +68,7 @@ struct userspace_mem_regions {
/* Memory encryption policy/configuration. */
struct vm_memcrypt {
bool enabled;
+ bool encrypted;
int8_t enc_by_default;
bool has_enc_bit;
int8_t enc_bit;
@@ -816,6 +817,8 @@ vm_paddr_t addr_arch_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva);

static inline vm_paddr_t addr_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva)
{
+ TEST_ASSERT(!vm->memcrypt.encrypted,
+ "Encrypted guests have their page tables encrypted so gva2gpa conversions are not possible.");
return addr_arch_gva2gpa(vm, gva);
}

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..2f7f7c741b12
--- /dev/null
+++ b/tools/testing/selftests/kvm/include/x86_64/sev.h
@@ -0,0 +1,44 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Helpers used for SEV guests
+ *
+ * Copyright (C) 2021 Advanced Micro Devices
+ */
+#ifndef SELFTEST_KVM_SEV_H
+#define SELFTEST_KVM_SEV_H
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "kvm_util.h"
+
+/* Makefile might set this separately for user-overrides */
+#ifndef SEV_DEV_PATH
+#define SEV_DEV_PATH "/dev/sev"
+#endif
+
+#define SEV_FW_REQ_VER_MAJOR 0
+#define SEV_FW_REQ_VER_MINOR 17
+
+#define SEV_POLICY_NO_DBG (1UL << 0)
+#define SEV_POLICY_ES (1UL << 2)
+
+enum {
+ SEV_GSTATE_UNINIT = 0,
+ SEV_GSTATE_LUPDATE,
+ SEV_GSTATE_LSECRET,
+ SEV_GSTATE_RUNNING,
+};
+
+struct sev_vm;
+
+void kvm_sev_ioctl(struct sev_vm *sev, int cmd, void *data);
+struct kvm_vm *sev_get_vm(struct sev_vm *sev);
+uint8_t sev_get_enc_bit(struct sev_vm *sev);
+
+struct sev_vm *sev_vm_create(uint32_t policy, uint64_t npages);
+void sev_vm_free(struct sev_vm *sev);
+void sev_vm_launch(struct sev_vm *sev);
+void sev_vm_launch_measure(struct sev_vm *sev, uint8_t *measurement);
+void sev_vm_launch_finish(struct sev_vm *sev);
+
+#endif /* SELFTEST_KVM_SEV_H */
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..3abcf50c0b5d
--- /dev/null
+++ b/tools/testing/selftests/kvm/lib/x86_64/sev.c
@@ -0,0 +1,251 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Helpers used for SEV guests
+ *
+ * Copyright (C) 2021 Advanced Micro Devices
+ */
+
+#include <stdint.h>
+#include <stdbool.h>
+#include "kvm_util.h"
+#include "linux/psp-sev.h"
+#include "processor.h"
+#include "sev.h"
+
+#define PAGE_SHIFT 12
+#define CPUID_MEM_ENC_LEAF 0x8000001f
+#define CPUID_EBX_CBIT_MASK 0x3f
+
+struct sev_vm {
+ struct kvm_vm *vm;
+ int fd;
+ int enc_bit;
+ uint32_t sev_policy;
+};
+
+/* Common SEV helpers/accessors. */
+
+struct kvm_vm *sev_get_vm(struct sev_vm *sev)
+{
+ return sev->vm;
+}
+
+uint8_t sev_get_enc_bit(struct sev_vm *sev)
+{
+ return sev->enc_bit;
+}
+
+void sev_ioctl(int sev_fd, int cmd, void *data)
+{
+ int ret;
+ struct sev_issue_cmd arg;
+
+ arg.cmd = cmd;
+ arg.data = (unsigned long)data;
+ ret = ioctl(sev_fd, SEV_ISSUE_CMD, &arg);
+ TEST_ASSERT(ret == 0,
+ "SEV ioctl %d failed, error: %d, fw_error: %d",
+ cmd, ret, arg.error);
+}
+
+void kvm_sev_ioctl(struct sev_vm *sev, int cmd, void *data)
+{
+ struct kvm_sev_cmd arg = {0};
+ int ret;
+
+ arg.id = cmd;
+ arg.sev_fd = sev->fd;
+ arg.data = (__u64)data;
+
+ ret = ioctl(sev->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);
+}
+
+/* Local helpers. */
+
+static void
+sev_register_user_region(struct sev_vm *sev, void *hva, uint64_t size)
+{
+ struct kvm_enc_region range = {0};
+ int ret;
+
+ pr_debug("%s: hva: %p, size: %lu\n", __func__, hva, size);
+
+ range.addr = (__u64)hva;
+ range.size = size;
+
+ ret = ioctl(sev->vm->fd, KVM_MEMORY_ENCRYPT_REG_REGION, &range);
+ TEST_ASSERT(ret == 0, "failed to register user range, errno: %i\n", errno);
+}
+
+static void
+sev_encrypt_phy_range(struct sev_vm *sev, 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(sev->vm, gpa);
+ ksev_update_data.len = size;
+
+ kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_UPDATE_DATA, &ksev_update_data);
+}
+
+static void sev_encrypt(struct sev_vm *sev)
+{
+ const struct sparsebit *enc_phy_pages;
+ struct kvm_vm *vm = sev->vm;
+ sparsebit_idx_t pg = 0;
+ vm_paddr_t gpa_start;
+ uint64_t memory_size;
+
+ /* Only memslot 0 supported for now. */
+ enc_phy_pages = vm_get_encrypted_phy_pages(sev->vm, 0, &gpa_start, &memory_size);
+ TEST_ASSERT(enc_phy_pages, "Unable to retrieve encrypted pages bitmap");
+ while (pg < (memory_size / vm->page_size)) {
+ sparsebit_idx_t pg_cnt;
+
+ if (sparsebit_is_clear(enc_phy_pages, pg)) {
+ pg = sparsebit_next_set(enc_phy_pages, pg);
+ if (!pg)
+ break;
+ }
+
+ pg_cnt = sparsebit_next_clear(enc_phy_pages, pg) - pg;
+ if (pg_cnt <= 0)
+ pg_cnt = 1;
+
+ sev_encrypt_phy_range(sev,
+ gpa_start + pg * vm->page_size,
+ pg_cnt * vm->page_size);
+ pg += pg_cnt;
+ }
+
+ sev->vm->memcrypt.encrypted = true;
+}
+
+/* SEV VM implementation. */
+
+static struct sev_vm *sev_vm_alloc(struct kvm_vm *vm)
+{
+ struct sev_user_data_status sev_status = {0};
+ uint32_t eax, ebx, ecx, edx;
+ struct sev_vm *sev;
+ int sev_fd;
+
+ sev_fd = open(SEV_DEV_PATH, O_RDWR);
+ if (sev_fd < 0) {
+ pr_info("Failed to open SEV device, path: %s, error: %d, skipping test.\n",
+ SEV_DEV_PATH, sev_fd);
+ return NULL;
+ }
+
+ sev_ioctl(sev_fd, 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 NULL;
+ }
+
+ sev = calloc(1, sizeof(*sev));
+ sev->fd = sev_fd;
+ sev->vm = vm;
+
+ /* Get encryption bit via CPUID. */
+ cpuid(CPUID_MEM_ENC_LEAF, &eax, &ebx, &ecx, &edx);
+ sev->enc_bit = ebx & CPUID_EBX_CBIT_MASK;
+
+ return sev;
+}
+
+void sev_vm_free(struct sev_vm *sev)
+{
+ ucall_uninit(sev->vm);
+ kvm_vm_free(sev->vm);
+ close(sev->fd);
+ free(sev);
+}
+
+struct sev_vm *sev_vm_create(uint32_t policy, uint64_t npages)
+{
+ struct sev_vm *sev;
+ struct kvm_vm *vm;
+
+ /* Need to handle memslots after init, and after setting memcrypt. */
+ vm = vm_create_barebones();
+ sev = sev_vm_alloc(vm);
+ if (!sev)
+ return NULL;
+ sev->sev_policy = policy;
+
+ kvm_sev_ioctl(sev, KVM_SEV_INIT, NULL);
+
+ vm->vpages_mapped = sparsebit_alloc();
+ vm_set_memory_encryption(vm, true, true, sev->enc_bit);
+ pr_info("SEV cbit: %d\n", sev->enc_bit);
+ vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS, 0, 0, npages, 0);
+ sev_register_user_region(sev, addr_gpa2hva(vm, 0),
+ npages * vm->page_size);
+
+ pr_info("SEV guest created, policy: 0x%x, size: %lu KB\n",
+ sev->sev_policy, npages * vm->page_size / 1024);
+
+ return sev;
+}
+
+void sev_vm_launch(struct sev_vm *sev)
+{
+ struct kvm_sev_launch_start ksev_launch_start = {0};
+ struct kvm_sev_guest_status ksev_status = {0};
+
+ /* Need to use ucall_shared for synchronization. */
+ //ucall_init_ops(sev_get_vm(sev), NULL, &ucall_ops_halt);
+
+ ksev_launch_start.policy = sev->sev_policy;
+ kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_START, &ksev_launch_start);
+ kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_status);
+ TEST_ASSERT(ksev_status.policy == sev->sev_policy, "Incorrect guest policy.");
+ TEST_ASSERT(ksev_status.state == SEV_GSTATE_LUPDATE,
+ "Unexpected guest state: %d", ksev_status.state);
+
+ ucall_init(sev->vm, NULL);
+
+ sev_encrypt(sev);
+}
+
+void sev_vm_launch_measure(struct sev_vm *sev, uint8_t *measurement)
+{
+ struct kvm_sev_launch_measure ksev_launch_measure = {0};
+ struct kvm_sev_guest_status ksev_guest_status = {0};
+
+ ksev_launch_measure.len = 256;
+ ksev_launch_measure.uaddr = (__u64)measurement;
+ kvm_sev_ioctl(sev, KVM_SEV_LAUNCH_MEASURE, &ksev_launch_measure);
+
+ /* Measurement causes a state transition, check that. */
+ kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_guest_status);
+ TEST_ASSERT(ksev_guest_status.state == SEV_GSTATE_LSECRET,
+ "Unexpected guest state: %d", ksev_guest_status.state);
+}
+
+void sev_vm_launch_finish(struct sev_vm *sev)
+{
+ struct kvm_sev_guest_status ksev_status = {0};
+
+ kvm_sev_ioctl(sev, 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(sev, KVM_SEV_LAUNCH_FINISH, NULL);
+
+ kvm_sev_ioctl(sev, KVM_SEV_GUEST_STATUS, &ksev_status);
+ TEST_ASSERT(ksev_status.state == SEV_GSTATE_RUNNING,
+ "Unexpected guest state: %d", ksev_status.state);
+}
--
2.37.1.559.g78731f0fdb-goog