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SubjectRe: [RFC 07/16] KVM: selftests: add SEV boot tests
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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;
> +}

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