Re: [RFC 07/16] KVM: selftests: add SEV boot tests

On 10/6/21 1:37 PM, 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@amd.com

tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/x86_64/sev_all_boot_test.c | 252 ++++++++++++++++++ 3 files changed, 254 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 0709af0144c8..824f100bec2a 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -38,6 +38,7 @@ /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 c7a5e1c69e0c..aa8901bdbd22 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -72,6 +72,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/tsc_msrs_test TEST_GEN_PROGS_x86_64 += x86_64/vmx_pmu_msrs_test 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/sev_all_boot_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/sev_all_boot_test.c b/tools/testing/selftests/kvm/x86_64/sev_all_boot_test.c new file mode 100644 index 000000000000..8df7143ac17d --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/sev_all_boot_test.c @@ -0,0 +1,252 @@ +// 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 sev_sync_data *sync) +{

• /* Initial guest check-in. */
• sev_guest_sync(sync, 1, 0);

+}

+static void check_test_start(struct kvm_vm *vm, struct sev_sync_data *sync) +{

• struct kvm_run *run;
• run = vcpu_state(vm, VCPU_ID);
• vcpu_run(vm, VCPU_ID);
• /* Initial guest check-in. */
• sev_check_guest_sync(run, sync, 1);

+}

+static void +guest_test_common(struct sev_sync_data *sync, uint8_t *shared_buf, uint8_t *private_buf) +{

• bool success;
• /* Initial check-in for common. */
• sev_guest_sync(sync, 100, 0);
• /* Ensure initial shared pages are intact. */
• success = check_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x41);
• SEV_GUEST_ASSERT(sync, 103, success);
• /* Ensure initial private pages are intact/encrypted. */
• success = check_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x42);
• SEV_GUEST_ASSERT(sync, 104, success);
• /* Ensure host userspace can't read newly-written encrypted data. */
• fill_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x43);
• sev_guest_sync(sync, 200, 0);
• /* Ensure guest can read newly-written shared data from host. */
• success = check_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x44);
• SEV_GUEST_ASSERT(sync, 201, success);
• /* Ensure host can read newly-written shared data from guest. */
• fill_buf(shared_buf, SHARED_PAGES, PAGE_STRIDE, 0x45);
• sev_guest_sync(sync, 300, 0);

+}

+static void +check_test_common(struct kvm_vm *vm, struct sev_sync_data *sync,

•   uint8_t *shared_buf, uint8_t *private_buf)
  

+{

• struct kvm_run *run = vcpu_state(vm, VCPU_ID);
• bool success;
• /* Initial guest check-in. */
• vcpu_run(vm, VCPU_ID);
• sev_check_guest_sync(run, sync, 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);
• sev_check_guest_sync(run, sync, 200);
• /* Ensure host userspace can't read newly-written encrypted data. */
• success = check_buf(private_buf, PRIVATE_PAGES, PAGE_STRIDE, 0x43);
• 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);
• sev_check_guest_sync(run, sync, 300);
• /* 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 sev_sync_data *sync) +{

• sev_guest_done(sync, 10000, 0);

+}

+static void +check_test_done(struct kvm_vm *vm, struct sev_sync_data *sync) +{

• struct kvm_run *run = vcpu_state(vm, VCPU_ID);
• vcpu_run(vm, VCPU_ID);
• sev_check_guest_done(run, sync, 10000);

+}

+static void __attribute__((__flatten__)) +guest_sev_code(struct sev_sync_data *sync, uint8_t *shared_buf, uint8_t *private_buf) +{

• uint32_t eax, ebx, ecx, edx;
• uint64_t sev_status;
• guest_test_start(sync);
• /* Check SEV CPUID bit. */
• eax = 0x8000001f;
• ecx = 0;
• cpuid(&eax, &ebx, &ecx, &edx);
• SEV_GUEST_ASSERT(sync, 2, eax & (1 << 1));
• /* Check SEV MSR bit. */
• sev_status = rdmsr(MSR_AMD64_SEV);
• SEV_GUEST_ASSERT(sync, 3, (sev_status & 0x1) == 1);

Is there any need to do the cpuid and MSR tests every time the guest code is executed ?

• guest_test_common(sync, shared_buf, private_buf);
• guest_test_done(sync);

+}

+static void +setup_test_common(struct sev_vm *sev, void *guest_code, vm_vaddr_t *sync_vaddr,

•   vm_vaddr_t *shared_vaddr, vm_vaddr_t *private_vaddr)
  

+{

• struct kvm_vm *vm = sev_get_vm(sev);
• uint8_t *shared_buf, *private_buf;
• /* 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 sync buffer. */
• *sync_vaddr = vm_vaddr_alloc_shared(vm, PAGE_SIZE, 0);
• /* 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);

+}

+static void test_sev(void *guest_code, uint64_t policy) +{

• vm_vaddr_t sync_vaddr, shared_vaddr, private_vaddr;
• uint8_t *shared_buf, *private_buf;
• struct sev_sync_data *sync;
• uint8_t measurement[512];
• struct sev_vm *sev;
• struct kvm_vm *vm;
• int i;
• sev = sev_vm_create(policy, TOTAL_PAGES);
• if (!sev)

• return;
  

• vm = sev_get_vm(sev);
• setup_test_common(sev, guest_code, &sync_vaddr, &shared_vaddr, &private_vaddr);
• /* Set up guest params. */
• vcpu_args_set(vm, VCPU_ID, 4, sync_vaddr, shared_vaddr, private_vaddr);
• sync = addr_gva2hva(vm, sync_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_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);

Since the above section of this function is actually setup code and is not running the test yet, it is best placed in a setup function. My suggestion is that you place the above section into a function called setup_test_common() and within that function you further separate out the SEV-related setup into a function called setup_test_sev() or something similar. Then call the top-level setup function from within main().

• /* Guest is ready to run. Do the tests. */
• check_test_start(vm, sync);
• check_test_common(vm, sync, shared_buf, private_buf);
• check_test_done(vm, sync);

These function names can be better. These functions are not just checking the result, they are actually running the guest code. So, may be, calling them 'test_start, test_common and test_done are better. I would just collapse them and place their code in test_sev() only if you separate the out the setup code as I suggested above.

• 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;

+}