Add a selftest to exercise implicit/explicit conversion functionality within KVM and verify: 1) Shared memory is visible to host userspace after conversion 2) Private memory is not visible to host userspace before/after conversion 3) Host userspace and guest can communicate over shared memory
Signed-off-by: Vishal Annapurve vannapurve@google.com --- tools/testing/selftests/kvm/.gitignore | 1 + tools/testing/selftests/kvm/Makefile | 1 + .../selftests/kvm/x86_64/private_mem_test.c | 262 ++++++++++++++++++ 3 files changed, 264 insertions(+) create mode 100644 tools/testing/selftests/kvm/x86_64/private_mem_test.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore index ec084a61a819..095b67dc632e 100644 --- a/tools/testing/selftests/kvm/.gitignore +++ b/tools/testing/selftests/kvm/.gitignore @@ -31,6 +31,7 @@ /x86_64/monitor_mwait_test /x86_64/nx_huge_pages_test /x86_64/platform_info_test +/x86_64/private_mem_test /x86_64/pmu_event_filter_test /x86_64/set_boot_cpu_id /x86_64/set_sregs_test diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 8fe72a60aef0..c5fc8ea2c843 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -94,6 +94,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/mmu_role_test TEST_GEN_PROGS_x86_64 += x86_64/monitor_mwait_test TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test TEST_GEN_PROGS_x86_64 += x86_64/pmu_event_filter_test +TEST_GEN_PROGS_x86_64 += x86_64/private_mem_test TEST_GEN_PROGS_x86_64 += x86_64/set_boot_cpu_id TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test TEST_GEN_PROGS_x86_64 += x86_64/smm_test diff --git a/tools/testing/selftests/kvm/x86_64/private_mem_test.c b/tools/testing/selftests/kvm/x86_64/private_mem_test.c new file mode 100644 index 000000000000..9f491e2a16bb --- /dev/null +++ b/tools/testing/selftests/kvm/x86_64/private_mem_test.c @@ -0,0 +1,262 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * tools/testing/selftests/kvm/lib/kvm_util.c + * + * Copyright (C) 2022, Google LLC. + */ +#define _GNU_SOURCE /* for program_invocation_short_name */ +#include <fcntl.h> +#include <limits.h> +#include <sched.h> +#include <signal.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/ioctl.h> + +#include <linux/compiler.h> +#include <linux/kernel.h> +#include <linux/kvm_para.h> +#include <linux/memfd.h> + +#include <test_util.h> +#include <kvm_util.h> +#include <private_mem.h> +#include <processor.h> + +#define VM_MEMSLOT0_PAGES (512 * 10) + +#define TEST_AREA_SLOT 10 +#define TEST_AREA_GPA 0xC0000000 +#define TEST_AREA_SIZE (2 * 1024 * 1024) +#define GUEST_TEST_MEM_OFFSET (1 * 1024 * 1024) +#define GUEST_TEST_MEM_SIZE (10 * 4096) + +#define VM_STAGE_PROCESSED(x) pr_info("Processed stage %s\n", #x) + +#define TEST_MEM_DATA_PAT1 0x66 +#define TEST_MEM_DATA_PAT2 0x99 +#define TEST_MEM_DATA_PAT3 0x33 +#define TEST_MEM_DATA_PAT4 0xaa +#define TEST_MEM_DATA_PAT5 0x12 + +static bool verify_mem_contents(void *mem, uint32_t size, uint8_t pat) +{ + uint8_t *buf = (uint8_t *)mem; + + for (uint32_t i = 0; i < size; i++) { + if (buf[i] != pat) + return false; + } + + return true; +} + +/* + * Add custom implementation for memset to avoid using standard/builtin memset + * which may use features like SSE/GOT that don't work with guest vm execution + * within selftests. + */ +void *memset(void *mem, int byte, size_t size) +{ + uint8_t *buf = (uint8_t *)mem; + + for (uint32_t i = 0; i < size; i++) + buf[i] = byte; + + return buf; +} + +static void populate_test_area(void *test_area_base, uint64_t pat) +{ + memset(test_area_base, pat, TEST_AREA_SIZE); +} + +static void populate_guest_test_mem(void *guest_test_mem, uint64_t pat) +{ + memset(guest_test_mem, pat, GUEST_TEST_MEM_SIZE); +} + +static bool verify_test_area(void *test_area_base, uint64_t area_pat, + uint64_t guest_pat) +{ + void *test_area1_base = test_area_base; + uint64_t test_area1_size = GUEST_TEST_MEM_OFFSET; + void *guest_test_mem = test_area_base + test_area1_size; + uint64_t guest_test_size = GUEST_TEST_MEM_SIZE; + void *test_area2_base = guest_test_mem + guest_test_size; + uint64_t test_area2_size = (TEST_AREA_SIZE - (GUEST_TEST_MEM_OFFSET + + GUEST_TEST_MEM_SIZE)); + + return (verify_mem_contents(test_area1_base, test_area1_size, area_pat) && + verify_mem_contents(guest_test_mem, guest_test_size, guest_pat) && + verify_mem_contents(test_area2_base, test_area2_size, area_pat)); +} + +#define GUEST_STARTED 0 +#define GUEST_PRIVATE_MEM_POPULATED 1 +#define GUEST_SHARED_MEM_POPULATED 2 +#define GUEST_PRIVATE_MEM_POPULATED2 3 +#define GUEST_IMPLICIT_MEM_CONV1 4 +#define GUEST_IMPLICIT_MEM_CONV2 5 + +/* + * Run memory conversion tests supporting two types of conversion: + * 1) Explicit: Execute KVM hypercall to map/unmap gpa range which will cause + * userspace exit to back/unback private memory. Subsequent accesses by guest + * to the gpa range will not cause exit to userspace. + * 2) Implicit: Execute KVM hypercall to update memory access to a gpa range as + * private/shared without exiting to userspace. Subsequent accesses by guest + * to the gpa range will result in KVM EPT/NPT faults and then exit to + * userspace for each page. + * + * Test memory conversion scenarios with following steps: + * 1) Access private memory using private access and verify that memory contents + * are not visible to userspace. + * 2) Convert memory to shared using explicit/implicit conversions and ensure + * that userspace is able to access the shared regions. + * 3) Convert memory back to private using explicit/implicit conversions and + * ensure that userspace is again not able to access converted private + * regions. + */ +static void guest_conv_test_fn(bool test_explicit_conv) +{ + void *test_area_base = (void *)TEST_AREA_GPA; + void *guest_test_mem = (void *)(TEST_AREA_GPA + GUEST_TEST_MEM_OFFSET); + uint64_t guest_test_size = GUEST_TEST_MEM_SIZE; + + guest_map_ucall_page_shared(); + GUEST_SYNC(GUEST_STARTED); + + populate_test_area(test_area_base, TEST_MEM_DATA_PAT1); + GUEST_SYNC(GUEST_PRIVATE_MEM_POPULATED); + GUEST_ASSERT(verify_test_area(test_area_base, TEST_MEM_DATA_PAT1, + TEST_MEM_DATA_PAT1)); + + if (test_explicit_conv) + guest_update_mem_map(TO_SHARED, (uint64_t)guest_test_mem, + guest_test_size); + else { + guest_update_mem_access(TO_SHARED, (uint64_t)guest_test_mem, + guest_test_size); + GUEST_SYNC(GUEST_IMPLICIT_MEM_CONV1); + } + + populate_guest_test_mem(guest_test_mem, TEST_MEM_DATA_PAT2); + + GUEST_SYNC(GUEST_SHARED_MEM_POPULATED); + GUEST_ASSERT(verify_test_area(test_area_base, TEST_MEM_DATA_PAT1, + TEST_MEM_DATA_PAT5)); + + if (test_explicit_conv) + guest_update_mem_map(TO_PRIVATE, (uint64_t)guest_test_mem, + guest_test_size); + else { + guest_update_mem_access(TO_PRIVATE, (uint64_t)guest_test_mem, + guest_test_size); + GUEST_SYNC(GUEST_IMPLICIT_MEM_CONV2); + } + + populate_guest_test_mem(guest_test_mem, TEST_MEM_DATA_PAT3); + GUEST_SYNC(GUEST_PRIVATE_MEM_POPULATED2); + + GUEST_ASSERT(verify_test_area(test_area_base, TEST_MEM_DATA_PAT1, + TEST_MEM_DATA_PAT3)); + GUEST_DONE(); +} + +static void conv_test_ioexit_fn(struct kvm_vm *vm, uint32_t uc_arg1) +{ + void *test_area_hva = addr_gpa2hva(vm, TEST_AREA_GPA); + void *guest_test_mem_hva = (test_area_hva + GUEST_TEST_MEM_OFFSET); + uint64_t guest_mem_gpa = (TEST_AREA_GPA + GUEST_TEST_MEM_OFFSET); + uint64_t guest_test_size = GUEST_TEST_MEM_SIZE; + + switch (uc_arg1) { + case GUEST_STARTED: + populate_test_area(test_area_hva, TEST_MEM_DATA_PAT4); + VM_STAGE_PROCESSED(GUEST_STARTED); + break; + case GUEST_PRIVATE_MEM_POPULATED: + TEST_ASSERT(verify_test_area(test_area_hva, TEST_MEM_DATA_PAT4, + TEST_MEM_DATA_PAT4), "failed"); + VM_STAGE_PROCESSED(GUEST_PRIVATE_MEM_POPULATED); + break; + case GUEST_SHARED_MEM_POPULATED: + TEST_ASSERT(verify_test_area(test_area_hva, TEST_MEM_DATA_PAT4, + TEST_MEM_DATA_PAT2), "failed"); + populate_guest_test_mem(guest_test_mem_hva, TEST_MEM_DATA_PAT5); + VM_STAGE_PROCESSED(GUEST_SHARED_MEM_POPULATED); + break; + case GUEST_PRIVATE_MEM_POPULATED2: + TEST_ASSERT(verify_test_area(test_area_hva, TEST_MEM_DATA_PAT4, + TEST_MEM_DATA_PAT5), "failed"); + VM_STAGE_PROCESSED(GUEST_PRIVATE_MEM_POPULATED2); + break; + case GUEST_IMPLICIT_MEM_CONV1: + /* + * For first implicit conversion, memory is already private so + * mark it private again just to zap the pte entries for the gpa + * range, so that subsequent accesses from the guest will + * generate ept/npt fault and memory conversion path will be + * exercised by KVM. + */ + vm_update_private_mem(vm, guest_mem_gpa, guest_test_size, + ALLOCATE_MEM); + VM_STAGE_PROCESSED(GUEST_IMPLICIT_MEM_CONV1); + break; + case GUEST_IMPLICIT_MEM_CONV2: + /* + * For second implicit conversion, memory is already shared so + * mark it shared again just to zap the pte entries for the gpa + * range, so that subsequent accesses from the guest will + * generate ept/npt fault and memory conversion path will be + * exercised by KVM. + */ + vm_update_private_mem(vm, guest_mem_gpa, guest_test_size, + UNBACK_MEM); + VM_STAGE_PROCESSED(GUEST_IMPLICIT_MEM_CONV2); + break; + default: + TEST_FAIL("Unknown stage %d\n", uc_arg1); + break; + } +} + +static void guest_explicit_conv_test_fn(void) +{ + guest_conv_test_fn(true); +} + +static void guest_implicit_conv_test_fn(void) +{ + guest_conv_test_fn(false); +} + +static void execute_memory_conversion_test(void) +{ + struct vm_setup_info info; + struct test_setup_info *test_info = &info.test_info; + + info.vm_mem_src = VM_MEM_SRC_ANONYMOUS; + info.memslot0_pages = VM_MEMSLOT0_PAGES; + test_info->test_area_gpa = TEST_AREA_GPA; + test_info->test_area_size = TEST_AREA_SIZE; + test_info->test_area_slot = TEST_AREA_SLOT; + info.ioexit_cb = conv_test_ioexit_fn; + + info.guest_fn = guest_explicit_conv_test_fn; + execute_vm_with_private_mem(&info); + + info.guest_fn = guest_implicit_conv_test_fn; + execute_vm_with_private_mem(&info); +} + +int main(int argc, char *argv[]) +{ + /* Tell stdout not to buffer its content */ + setbuf(stdout, NULL); + + execute_memory_conversion_test(); + return 0; +}