On Thu, Dec 16, 2021, Michael Roth wrote:
> A common aspect of booting SEV guests is checking related CPUID/MSR
> bits and accessing shared/private memory. Add a basic test to cover
> this.
>
> This test will be expanded to cover basic boot of SEV-ES and SEV-SNP in
> subsequent patches.
>
> Signed-off-by: Michael Roth <michael.roth@xxxxxxx>
> ---
> tools/testing/selftests/kvm/.gitignore | 1 +
> tools/testing/selftests/kvm/Makefile | 1 +
> .../selftests/kvm/x86_64/sev_all_boot_test.c | 255 ++++++++++++++++++
> 3 files changed, 257 insertions(+)
> create mode 100644 tools/testing/selftests/kvm/x86_64/sev_all_boot_test.c
>
> diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
> index 4a801cba9c62..cc73de938a2a 100644
> --- a/tools/testing/selftests/kvm/.gitignore
> +++ b/tools/testing/selftests/kvm/.gitignore
> @@ -43,6 +43,7 @@
> /x86_64/xen_vmcall_test
> /x86_64/xss_msr_test
> /x86_64/vmx_pmu_msrs_test
> +/x86_64/sev_all_boot_test
> /access_tracking_perf_test
> /demand_paging_test
> /dirty_log_test
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index ccc382a827f1..6f250e190fde 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -81,6 +81,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/xen_shinfo_test
> TEST_GEN_PROGS_x86_64 += x86_64/xen_vmcall_test
> TEST_GEN_PROGS_x86_64 += x86_64/vmx_pi_mmio_test
> TEST_GEN_PROGS_x86_64 += x86_64/sev_migrate_tests
> +TEST_GEN_PROGS_x86_64 += x86_64/sev_all_boot_test
> TEST_GEN_PROGS_x86_64 += demand_paging_test
> TEST_GEN_PROGS_x86_64 += dirty_log_test
> TEST_GEN_PROGS_x86_64 += dirty_log_perf_test
> diff --git a/tools/testing/selftests/kvm/x86_64/sev_all_boot_test.c b/tools/testing/selftests/kvm/x86_64/sev_all_boot_test.c
> new file mode 100644
> index 000000000000..329a740a7cb2
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/x86_64/sev_all_boot_test.c
> @@ -0,0 +1,255 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Basic SEV boot tests.
> + *
> + * Copyright (C) 2021 Advanced Micro Devices
> + */
> +#define _GNU_SOURCE /* for program_invocation_short_name */
> +#include <fcntl.h>
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <string.h>
> +#include <sys/ioctl.h>
> +
> +#include "test_util.h"
> +
> +#include "kvm_util.h"
> +#include "processor.h"
> +#include "svm_util.h"
> +#include "linux/psp-sev.h"
> +#include "sev.h"
> +
> +#define VCPU_ID 2
> +#define PAGE_SIZE 4096
> +#define PAGE_STRIDE 32
> +
> +#define SHARED_PAGES 8192
> +#define SHARED_VADDR_MIN 0x1000000
> +
> +#define PRIVATE_PAGES 2048
> +#define PRIVATE_VADDR_MIN (SHARED_VADDR_MIN + SHARED_PAGES * PAGE_SIZE)
> +
> +#define TOTAL_PAGES (512 + SHARED_PAGES + PRIVATE_PAGES)
> +
> +static void fill_buf(uint8_t *buf, size_t pages, size_t stride, uint8_t val)
> +{
> + int i, j;
> +
> + for (i = 0; i < pages; i++)
> + for (j = 0; j < PAGE_SIZE; j += stride)
> + buf[i * PAGE_SIZE + j] = val;
> +}
> +
> +static bool check_buf(uint8_t *buf, size_t pages, size_t stride, uint8_t val)
> +{
> + int i, j;
> +
> + for (i = 0; i < pages; i++)
> + for (j = 0; j < PAGE_SIZE; j += stride)
> + if (buf[i * PAGE_SIZE + j] != val)
> + return false;
> +
> + return true;
> +}
> +
> +static void guest_test_start(struct ucall *uc)
> +{
> + /* Initial guest check-in. */
> + GUEST_SHARED_SYNC(uc, 1);
> +}
> +
> +static void test_start(struct kvm_vm *vm, struct ucall *uc)
> +{
> + vcpu_run(vm, VCPU_ID);
> +
> + /* Initial guest check-in. */
> + CHECK_SHARED_SYNC(vm, VCPU_ID, uc, 1);
> +}
> +
> +static void
> +guest_test_common(struct ucall *uc, uint8_t *shared_buf, uint8_t *private_buf)
> +{
> + bool success;
> +
> + /* Initial check-in for common. */
> + GUEST_SHARED_SYNC(uc, 100);
Probably, you want to use macros to represent those states which should
make it more clear. Otherwise, it is quite cumbersome for readers to
remember the meaning (or state) of 100/101/102.
> +
> + /* Ensure initial shared pages are intact. */
> + success = check_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x41);
> + GUEST_SHARED_ASSERT(uc, success);
> +
> + /* Ensure initial private pages are intact/encrypted. */
> + success = check_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x42);
> + GUEST_SHARED_ASSERT(uc, success);
> +
> + /* Ensure host userspace can't read newly-written encrypted data. */
> + fill_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x43);
> +
> + GUEST_SHARED_SYNC(uc, 101);
ditto.
> +
> + /* Ensure guest can read newly-written shared data from host. */
> + success = check_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x44);
> + GUEST_SHARED_ASSERT(uc, success);
> +
> + /* Ensure host can read newly-written shared data from guest. */
> + fill_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x45);
> +
> + GUEST_SHARED_SYNC(uc, 102);
ditto.
> +}
> +
> +static void
> +test_common(struct kvm_vm *vm, struct ucall *uc,
> + uint8_t *shared_buf, uint8_t *private_buf)
> +{
> + bool success;
> +
> + /* Initial guest check-in. */
> + vcpu_run(vm, VCPU_ID);
> + CHECK_SHARED_SYNC(vm, VCPU_ID, uc, 100);
> +
> + /* Ensure initial private pages are intact/encrypted. */
> + success = check_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x42);
> + TEST_ASSERT(!success, "Initial guest memory not encrypted!");
> +
> + vcpu_run(vm, VCPU_ID);
> + CHECK_SHARED_SYNC(vm, VCPU_ID, uc, 101);
> +
> + /* Ensure host userspace can't read newly-written encrypted data. */
> + success = check_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x43);
I am not sure if it is safe here. Since the cache coherency is not there
for neither SEV or SEV-ES. Reading confidential memory from host side
will generate cache lines that is not coherent with the guest. So might
be better to add clfush here?
> + TEST_ASSERT(!success, "Modified guest memory not encrypted!");
> +
> + /* Ensure guest can read newly-written shared data from host. */
> + fill_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x44);
> +
> + vcpu_run(vm, VCPU_ID);
> + CHECK_SHARED_SYNC(vm, VCPU_ID, uc, 102);
> +
> + /* Ensure host can read newly-written shared data from guest. */
> + success = check_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x45);
> + TEST_ASSERT(success, "Host can't read shared guest memory!");
> +}
> +
> +static void
> +guest_test_done(struct ucall *uc)
> +{
> + GUEST_SHARED_DONE(uc);
> +}
> +
> +static void
> +test_done(struct kvm_vm *vm, struct ucall *uc)
> +{
> + vcpu_run(vm, VCPU_ID);
> + CHECK_SHARED_DONE(vm, VCPU_ID, uc);
> +}
> +
> +static void __attribute__((__flatten__))
> +guest_sev_code(struct ucall *uc, uint8_t *shared_buf, uint8_t *private_buf)
> +{
> + uint32_t eax, ebx, ecx, edx;
> + uint64_t sev_status;
> +
> + guest_test_start(uc);
> +
> + /* Check SEV CPUID bit. */
> + eax = 0x8000001f;
> + ecx = 0;
> + cpuid(&eax, &ebx, &ecx, &edx);
> + GUEST_SHARED_ASSERT(uc, eax & (1 << 1));
> +
> + /* Check SEV MSR bit. */
> + sev_status = rdmsr(MSR_AMD64_SEV);
> + GUEST_SHARED_ASSERT(uc, (sev_status & 0x1) == 1);
> +
> + guest_test_common(uc, shared_buf, private_buf);
> +
> + guest_test_done(uc);
> +}
> +
> +static struct sev_vm *
> +setup_test_common(void *guest_code, uint64_t policy, struct ucall **uc,
> + uint8_t **shared_buf, uint8_t **private_buf)
> +{
> + vm_vaddr_t uc_vaddr, shared_vaddr, private_vaddr;
> + uint8_t measurement[512];
> + struct sev_vm *sev;
> + struct kvm_vm *vm;
> + int i;
> +
> + sev = sev_vm_create(policy, TOTAL_PAGES);
> + if (!sev)
> + return NULL;
> + vm = sev_get_vm(sev);
> +
> + /* Set up VCPU and initial guest kernel. */
> + vm_vcpu_add_default(vm, VCPU_ID, guest_code);
> + kvm_vm_elf_load(vm, program_invocation_name);
> +
> + /* Set up shared ucall buffer. */
> + uc_vaddr = ucall_shared_alloc(vm, 1);
> +
> + /* Set up buffer for reserved shared memory. */
> + shared_vaddr = vm_vaddr_alloc_shared(vm, SHARED_PAGES * PAGE_SIZE,
> + SHARED_VADDR_MIN);
> + *shared_buf = addr_gva2hva(vm, shared_vaddr);
> + fill_buf(*shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x41);
> +
> + /* Set up buffer for reserved private memory. */
> + private_vaddr = vm_vaddr_alloc(vm, PRIVATE_PAGES * PAGE_SIZE,
> + PRIVATE_VADDR_MIN);
> + *private_buf = addr_gva2hva(vm, private_vaddr);
> + fill_buf(*private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x42);
> +
> + /* Set up guest params. */
> + vcpu_args_set(vm, VCPU_ID, 4, uc_vaddr, shared_vaddr, private_vaddr);
> +
> + /*
> + * Hand these back to test harness, translation is needed now since page
> + * table will be encrypted after SEV VM launch.
> + */
> + *uc = addr_gva2hva(vm, uc_vaddr);
> + *shared_buf = addr_gva2hva(vm, shared_vaddr);
> + *private_buf = addr_gva2hva(vm, private_vaddr);
> +
> + /* Allocations/setup done. Encrypt initial guest payload. */
> + sev_vm_launch(sev);
> +
> + /* Dump the initial measurement. A test to actually verify it would be nice. */
> + sev_vm_launch_measure(sev, measurement);
> + pr_info("guest measurement: ");
> + for (i = 0; i < 32; ++i)
> + pr_info("%02x", measurement[i]);
> + pr_info("\n");
> +
> + sev_vm_launch_finish(sev);
> +
> + return sev;
> +}
> +
> +static void test_sev(void *guest_code, uint64_t policy)
> +{
> + uint8_t *shared_buf, *private_buf;
> + struct sev_vm *sev;
> + struct kvm_vm *vm;
> + struct ucall *uc;
> +
> + sev = setup_test_common(guest_code, policy, &uc, &shared_buf, &private_buf);
> + if (!sev)
> + return;
> + vm = sev_get_vm(sev);
> +
> + /* Guest is ready to run. Do the tests. */
> + test_start(vm, uc);
> + test_common(vm, uc, shared_buf, private_buf);
> + test_done(vm, uc);
> +
> + sev_vm_free(sev);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + /* SEV tests */
> + test_sev(guest_sev_code, SEV_POLICY_NO_DBG);
> + test_sev(guest_sev_code, 0);
> +
> + return 0;
> +}
> --
> 2.25.1
>
