1 files changed, 296 insertions, 0 deletions
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c
new file mode 100644
index 000000000..b0e1fc4de
--- /dev/null
+++ b/tools/testing/selftests/kvm/demand_paging_test.c
@@ -0,0 +1,296 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KVM demand paging test
+ * Adapted from dirty_log_test.c
+ *
+ * Copyright (C) 2018, Red Hat, Inc.
+ * Copyright (C) 2019, Google, Inc.
+ */
+
+#define _GNU_SOURCE /* for pipe2 */
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+#include <poll.h>
+#include <pthread.h>
+#include <linux/userfaultfd.h>
+#include <sys/syscall.h>
+
+#include "kvm_util.h"
+#include "test_util.h"
+#include "memstress.h"
+#include "guest_modes.h"
+#include "userfaultfd_util.h"
+
+#ifdef __NR_userfaultfd
+
+static int nr_vcpus = 1;
+static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
+
+static size_t demand_paging_size;
+static char *guest_data_prototype;
+
+static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
+{
+	struct kvm_vcpu *vcpu = vcpu_args->vcpu;
+	int vcpu_idx = vcpu_args->vcpu_idx;
+	struct kvm_run *run = vcpu->run;
+	struct timespec start;
+	struct timespec ts_diff;
+	int ret;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	/* Let the guest access its memory */
+	ret = _vcpu_run(vcpu);
+	TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
+	if (get_ucall(vcpu, NULL) != UCALL_SYNC) {
+		TEST_ASSERT(false,
+			    "Invalid guest sync status: exit_reason=%s\n",
+			    exit_reason_str(run->exit_reason));
+	}
+
+	ts_diff = timespec_elapsed(start);
+	PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_idx,
+		       ts_diff.tv_sec, ts_diff.tv_nsec);
+}
+
+static int handle_uffd_page_request(int uffd_mode, int uffd,
+		struct uffd_msg *msg)
+{
+	pid_t tid = syscall(__NR_gettid);
+	uint64_t addr = msg->arg.pagefault.address;
+	struct timespec start;
+	struct timespec ts_diff;
+	int r;
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+
+	if (uffd_mode == UFFDIO_REGISTER_MODE_MISSING) {
+		struct uffdio_copy copy;
+
+		copy.src = (uint64_t)guest_data_prototype;
+		copy.dst = addr;
+		copy.len = demand_paging_size;
+		copy.mode = 0;
+
+		r = ioctl(uffd, UFFDIO_COPY, &copy);
+		if (r == -1) {
+			pr_info("Failed UFFDIO_COPY in 0x%lx from thread %d with errno: %d\n",
+				addr, tid, errno);
+			return r;
+		}
+	} else if (uffd_mode == UFFDIO_REGISTER_MODE_MINOR) {
+		struct uffdio_continue cont = {0};
+
+		cont.range.start = addr;
+		cont.range.len = demand_paging_size;
+
+		r = ioctl(uffd, UFFDIO_CONTINUE, &cont);
+		if (r == -1) {
+			pr_info("Failed UFFDIO_CONTINUE in 0x%lx from thread %d with errno: %d\n",
+				addr, tid, errno);
+			return r;
+		}
+	} else {
+		TEST_FAIL("Invalid uffd mode %d", uffd_mode);
+	}
+
+	ts_diff = timespec_elapsed(start);
+
+	PER_PAGE_DEBUG("UFFD page-in %d \t%ld ns\n", tid,
+		       timespec_to_ns(ts_diff));
+	PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
+		       demand_paging_size, addr, tid);
+
+	return 0;
+}
+
+struct test_params {
+	int uffd_mode;
+	useconds_t uffd_delay;
+	enum vm_mem_backing_src_type src_type;
+	bool partition_vcpu_memory_access;
+};
+
+static void prefault_mem(void *alias, uint64_t len)
+{
+	size_t p;
+
+	TEST_ASSERT(alias != NULL, "Alias required for minor faults");
+	for (p = 0; p < (len / demand_paging_size); ++p) {
+		memcpy(alias + (p * demand_paging_size),
+		       guest_data_prototype, demand_paging_size);
+	}
+}
+
+static void run_test(enum vm_guest_mode mode, void *arg)
+{
+	struct test_params *p = arg;
+	struct uffd_desc **uffd_descs = NULL;
+	struct timespec start;
+	struct timespec ts_diff;
+	struct kvm_vm *vm;
+	int i;
+
+	vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size, 1,
+				 p->src_type, p->partition_vcpu_memory_access);
+
+	demand_paging_size = get_backing_src_pagesz(p->src_type);
+
+	guest_data_prototype = malloc(demand_paging_size);
+	TEST_ASSERT(guest_data_prototype,
+		    "Failed to allocate buffer for guest data pattern");
+	memset(guest_data_prototype, 0xAB, demand_paging_size);
+
+	if (p->uffd_mode) {
+		uffd_descs = malloc(nr_vcpus * sizeof(struct uffd_desc *));
+		TEST_ASSERT(uffd_descs, "Memory allocation failed");
+
+		for (i = 0; i < nr_vcpus; i++) {
+			struct memstress_vcpu_args *vcpu_args;
+			void *vcpu_hva;
+			void *vcpu_alias;
+
+			vcpu_args = &memstress_args.vcpu_args[i];
+
+			/* Cache the host addresses of the region */
+			vcpu_hva = addr_gpa2hva(vm, vcpu_args->gpa);
+			vcpu_alias = addr_gpa2alias(vm, vcpu_args->gpa);
+
+			prefault_mem(vcpu_alias,
+				vcpu_args->pages * memstress_args.guest_page_size);
+
+			/*
+			 * Set up user fault fd to handle demand paging
+			 * requests.
+			 */
+			uffd_descs[i] = uffd_setup_demand_paging(
+				p->uffd_mode, p->uffd_delay, vcpu_hva,
+				vcpu_args->pages * memstress_args.guest_page_size,
+				&handle_uffd_page_request);
+		}
+	}
+
+	pr_info("Finished creating vCPUs and starting uffd threads\n");
+
+	clock_gettime(CLOCK_MONOTONIC, &start);
+	memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);
+	pr_info("Started all vCPUs\n");
+
+	memstress_join_vcpu_threads(nr_vcpus);
+	ts_diff = timespec_elapsed(start);
+	pr_info("All vCPU threads joined\n");
+
+	if (p->uffd_mode) {
+		/* Tell the user fault fd handler threads to quit */
+		for (i = 0; i < nr_vcpus; i++)
+			uffd_stop_demand_paging(uffd_descs[i]);
+	}
+
+	pr_info("Total guest execution time: %ld.%.9lds\n",
+		ts_diff.tv_sec, ts_diff.tv_nsec);
+	pr_info("Overall demand paging rate: %f pgs/sec\n",
+		memstress_args.vcpu_args[0].pages * nr_vcpus /
+		((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
+
+	memstress_destroy_vm(vm);
+
+	free(guest_data_prototype);
+	if (p->uffd_mode)
+		free(uffd_descs);
+}
+
+static void help(char *name)
+{
+	puts("");
+	printf("usage: %s [-h] [-m vm_mode] [-u uffd_mode] [-d uffd_delay_usec]\n"
+	       "          [-b memory] [-s type] [-v vcpus] [-o]\n", name);
+	guest_modes_help();
+	printf(" -u: use userfaultfd to handle vCPU page faults. Mode is a\n"
+	       "     UFFD registration mode: 'MISSING' or 'MINOR'.\n");
+	printf(" -d: add a delay in usec to the User Fault\n"
+	       "     FD handler to simulate demand paging\n"
+	       "     overheads. Ignored without -u.\n");
+	printf(" -b: specify the size of the memory region which should be\n"
+	       "     demand paged by each vCPU. e.g. 10M or 3G.\n"
+	       "     Default: 1G\n");
+	backing_src_help("-s");
+	printf(" -v: specify the number of vCPUs to run.\n");
+	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
+	       "     them into a separate region of memory for each vCPU.\n");
+	puts("");
+	exit(0);
+}
+
+int main(int argc, char *argv[])
+{
+	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
+	struct test_params p = {
+		.src_type = DEFAULT_VM_MEM_SRC,
+		.partition_vcpu_memory_access = true,
+	};
+	int opt;
+
+	guest_modes_append_default();
+
+	while ((opt = getopt(argc, argv, "hm:u:d:b:s:v:o")) != -1) {
+		switch (opt) {
+		case 'm':
+			guest_modes_cmdline(optarg);
+			break;
+		case 'u':
+			if (!strcmp("MISSING", optarg))
+				p.uffd_mode = UFFDIO_REGISTER_MODE_MISSING;
+			else if (!strcmp("MINOR", optarg))
+				p.uffd_mode = UFFDIO_REGISTER_MODE_MINOR;
+			TEST_ASSERT(p.uffd_mode, "UFFD mode must be 'MISSING' or 'MINOR'.");
+			break;
+		case 'd':
+			p.uffd_delay = strtoul(optarg, NULL, 0);
+			TEST_ASSERT(p.uffd_delay >= 0, "A negative UFFD delay is not supported.");
+			break;
+		case 'b':
+			guest_percpu_mem_size = parse_size(optarg);
+			break;
+		case 's':
+			p.src_type = parse_backing_src_type(optarg);
+			break;
+		case 'v':
+			nr_vcpus = atoi_positive("Number of vCPUs", optarg);
+			TEST_ASSERT(nr_vcpus <= max_vcpus,
+				    "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
+			break;
+		case 'o':
+			p.partition_vcpu_memory_access = false;
+			break;
+		case 'h':
+		default:
+			help(argv[0]);
+			break;
+		}
+	}
+
+	if (p.uffd_mode == UFFDIO_REGISTER_MODE_MINOR &&
+	    !backing_src_is_shared(p.src_type)) {
+		TEST_FAIL("userfaultfd MINOR mode requires shared memory; pick a different -s");
+	}
+
+	for_each_guest_mode(run_test, &p);
+
+	return 0;
+}
+
+#else /* __NR_userfaultfd */
+
+#warning "missing __NR_userfaultfd definition"
+
+int main(void)
+{
+	print_skip("__NR_userfaultfd must be present for userfaultfd test");
+	return KSFT_SKIP;
+}
+
+#endif /* __NR_userfaultfd */