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32 results

demand_paging_test.c

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  • demand_paging_test.c 12.29 KiB
    // 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 program_invocation_name */
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <sys/syscall.h>
    #include <unistd.h>
    #include <asm/unistd.h>
    #include <time.h>
    #include <poll.h>
    #include <pthread.h>
    #include <linux/bitmap.h>
    #include <linux/bitops.h>
    #include <linux/userfaultfd.h>
    
    #include "perf_test_util.h"
    #include "processor.h"
    #include "test_util.h"
    
    #ifdef __NR_userfaultfd
    
    #define DEFAULT_GUEST_TEST_MEM_SIZE (1 << 30) /* 1G */
    
    #ifdef PRINT_PER_PAGE_UPDATES
    #define PER_PAGE_DEBUG(...) printf(__VA_ARGS__)
    #else
    #define PER_PAGE_DEBUG(...) _no_printf(__VA_ARGS__)
    #endif
    
    #ifdef PRINT_PER_VCPU_UPDATES
    #define PER_VCPU_DEBUG(...) printf(__VA_ARGS__)
    #else
    #define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__)
    #endif
    
    static char *guest_data_prototype;
    
    static void *vcpu_worker(void *data)
    {
    	int ret;
    	struct vcpu_args *vcpu_args = (struct vcpu_args *)data;
    	int vcpu_id = vcpu_args->vcpu_id;
    	struct kvm_vm *vm = perf_test_args.vm;
    	struct kvm_run *run;
    	struct timespec start;
    	struct timespec ts_diff;
    
    	vcpu_args_set(vm, vcpu_id, 1, vcpu_id);
    	run = vcpu_state(vm, vcpu_id);
    
    	clock_gettime(CLOCK_MONOTONIC, &start);
    
    	/* Let the guest access its memory */
    	ret = _vcpu_run(vm, vcpu_id);
    	TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
    	if (get_ucall(vm, vcpu_id, NULL) != UCALL_SYNC) {
    		TEST_ASSERT(false,
    			    "Invalid guest sync status: exit_reason=%s\n",
    			    exit_reason_str(run->exit_reason));
    	}
    
    	ts_diff = timespec_diff_now(start);
    	PER_VCPU_DEBUG("vCPU %d execution time: %ld.%.9lds\n", vcpu_id,
    		       ts_diff.tv_sec, ts_diff.tv_nsec);
    
    	return NULL;
    }
    
    static int handle_uffd_page_request(int uffd, uint64_t addr)
    {
    	pid_t tid;
    	struct timespec start;
    	struct timespec ts_diff;
    	struct uffdio_copy copy;
    	int r;
    
    	tid = syscall(__NR_gettid);
    
    	copy.src = (uint64_t)guest_data_prototype;
    	copy.dst = addr;
    	copy.len = perf_test_args.host_page_size;
    	copy.mode = 0;
    
    	clock_gettime(CLOCK_MONOTONIC, &start);
    
    	r = ioctl(uffd, UFFDIO_COPY, &copy);
    	if (r == -1) {
    		pr_info("Failed Paged in 0x%lx from thread %d with errno: %d\n",
    			addr, tid, errno);
    		return r;
    	}
    
    	ts_diff = timespec_diff_now(start);
    
    	PER_PAGE_DEBUG("UFFDIO_COPY %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",
    		       perf_test_args.host_page_size, addr, tid);
    
    	return 0;
    }
    
    bool quit_uffd_thread;
    
    struct uffd_handler_args {
    	int uffd;
    	int pipefd;
    	useconds_t delay;
    };
    
    static void *uffd_handler_thread_fn(void *arg)
    {
    	struct uffd_handler_args *uffd_args = (struct uffd_handler_args *)arg;
    	int uffd = uffd_args->uffd;
    	int pipefd = uffd_args->pipefd;
    	useconds_t delay = uffd_args->delay;
    	int64_t pages = 0;
    	struct timespec start;
    	struct timespec ts_diff;
    
    	clock_gettime(CLOCK_MONOTONIC, &start);
    	while (!quit_uffd_thread) {
    		struct uffd_msg msg;
    		struct pollfd pollfd[2];
    		char tmp_chr;
    		int r;
    		uint64_t addr;
    
    		pollfd[0].fd = uffd;
    		pollfd[0].events = POLLIN;
    		pollfd[1].fd = pipefd;
    		pollfd[1].events = POLLIN;
    
    		r = poll(pollfd, 2, -1);
    		switch (r) {
    		case -1:
    			pr_info("poll err");
    			continue;
    		case 0:
    			continue;
    		case 1:
    			break;
    		default:
    			pr_info("Polling uffd returned %d", r);
    			return NULL;
    		}
    
    		if (pollfd[0].revents & POLLERR) {
    			pr_info("uffd revents has POLLERR");
    			return NULL;
    		}
    
    		if (pollfd[1].revents & POLLIN) {
    			r = read(pollfd[1].fd, &tmp_chr, 1);
    			TEST_ASSERT(r == 1,
    				    "Error reading pipefd in UFFD thread\n");
    			return NULL;
    		}
    
    		if (!pollfd[0].revents & POLLIN)
    			continue;
    
    		r = read(uffd, &msg, sizeof(msg));
    		if (r == -1) {
    			if (errno == EAGAIN)
    				continue;
    			pr_info("Read of uffd gor errno %d", errno);
    			return NULL;
    		}
    
    		if (r != sizeof(msg)) {
    			pr_info("Read on uffd returned unexpected size: %d bytes", r);
    			return NULL;
    		}
    
    		if (!(msg.event & UFFD_EVENT_PAGEFAULT))
    			continue;
    
    		if (delay)
    			usleep(delay);
    		addr =  msg.arg.pagefault.address;
    		r = handle_uffd_page_request(uffd, addr);
    		if (r < 0)
    			return NULL;
    		pages++;
    	}
    
    	ts_diff = timespec_diff_now(start);
    	PER_VCPU_DEBUG("userfaulted %ld pages over %ld.%.9lds. (%f/sec)\n",
    		       pages, ts_diff.tv_sec, ts_diff.tv_nsec,
    		       pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
    
    	return NULL;
    }
    
    static int setup_demand_paging(struct kvm_vm *vm,
    			       pthread_t *uffd_handler_thread, int pipefd,
    			       useconds_t uffd_delay,
    			       struct uffd_handler_args *uffd_args,
    			       void *hva, uint64_t len)
    {
    	int uffd;
    	struct uffdio_api uffdio_api;
    	struct uffdio_register uffdio_register;
    
    	uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
    	if (uffd == -1) {
    		pr_info("uffd creation failed\n");
    		return -1;
    	}
    
    	uffdio_api.api = UFFD_API;
    	uffdio_api.features = 0;
    	if (ioctl(uffd, UFFDIO_API, &uffdio_api) == -1) {
    		pr_info("ioctl uffdio_api failed\n");
    		return -1;
    	}
    
    	uffdio_register.range.start = (uint64_t)hva;
    	uffdio_register.range.len = len;
    	uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
    	if (ioctl(uffd, UFFDIO_REGISTER, &uffdio_register) == -1) {
    		pr_info("ioctl uffdio_register failed\n");
    		return -1;
    	}
    
    	if ((uffdio_register.ioctls & UFFD_API_RANGE_IOCTLS) !=
    			UFFD_API_RANGE_IOCTLS) {
    		pr_info("unexpected userfaultfd ioctl set\n");
    		return -1;
    	}
    
    	uffd_args->uffd = uffd;
    	uffd_args->pipefd = pipefd;
    	uffd_args->delay = uffd_delay;
    	pthread_create(uffd_handler_thread, NULL, uffd_handler_thread_fn,
    		       uffd_args);
    
    	PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n",
    		       hva, hva + len);
    
    	return 0;
    }
    
    static void run_test(enum vm_guest_mode mode, bool use_uffd,
    		     useconds_t uffd_delay, int vcpus,
    		     uint64_t vcpu_memory_bytes)
    {
    	pthread_t *vcpu_threads;
    	pthread_t *uffd_handler_threads = NULL;
    	struct uffd_handler_args *uffd_args = NULL;
    	struct timespec start;
    	struct timespec ts_diff;
    	int *pipefds = NULL;
    	struct kvm_vm *vm;
    	int vcpu_id;
    	int r;
    
    	vm = create_vm(mode, vcpus, vcpu_memory_bytes);
    
    	guest_data_prototype = malloc(perf_test_args.host_page_size);
    	TEST_ASSERT(guest_data_prototype,
    		    "Failed to allocate buffer for guest data pattern");
    	memset(guest_data_prototype, 0xAB, perf_test_args.host_page_size);
    
    	vcpu_threads = malloc(vcpus * sizeof(*vcpu_threads));
    	TEST_ASSERT(vcpu_threads, "Memory allocation failed");
    
    	add_vcpus(vm, vcpus, vcpu_memory_bytes);
    
    	if (use_uffd) {
    		uffd_handler_threads =
    			malloc(vcpus * sizeof(*uffd_handler_threads));
    		TEST_ASSERT(uffd_handler_threads, "Memory allocation failed");
    
    		uffd_args = malloc(vcpus * sizeof(*uffd_args));
    		TEST_ASSERT(uffd_args, "Memory allocation failed");
    
    		pipefds = malloc(sizeof(int) * vcpus * 2);
    		TEST_ASSERT(pipefds, "Unable to allocate memory for pipefd");
    
    		for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
    			vm_paddr_t vcpu_gpa;
    			void *vcpu_hva;
    
    			vcpu_gpa = guest_test_phys_mem + (vcpu_id * vcpu_memory_bytes);
    			PER_VCPU_DEBUG("Added VCPU %d with test mem gpa [%lx, %lx)\n",
    				       vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_memory_bytes);
    
    			/* Cache the HVA pointer of the region */
    			vcpu_hva = addr_gpa2hva(vm, vcpu_gpa);
    
    			/*
    			 * Set up user fault fd to handle demand paging
    			 * requests.
    			 */
    			r = pipe2(&pipefds[vcpu_id * 2],
    				  O_CLOEXEC | O_NONBLOCK);
    			TEST_ASSERT(!r, "Failed to set up pipefd");
    
    			r = setup_demand_paging(vm,
    						&uffd_handler_threads[vcpu_id],
    						pipefds[vcpu_id * 2],
    						uffd_delay, &uffd_args[vcpu_id],
    						vcpu_hva, vcpu_memory_bytes);
    			if (r < 0)
    				exit(-r);
    		}
    	}
    
    	/* Export the shared variables to the guest */
    	sync_global_to_guest(vm, perf_test_args);
    
    	pr_info("Finished creating vCPUs and starting uffd threads\n");
    
    	clock_gettime(CLOCK_MONOTONIC, &start);
    
    	for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
    		pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker,
    			       &perf_test_args.vcpu_args[vcpu_id]);
    	}
    
    	pr_info("Started all vCPUs\n");
    
    	/* Wait for the vcpu threads to quit */
    	for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
    		pthread_join(vcpu_threads[vcpu_id], NULL);
    		PER_VCPU_DEBUG("Joined thread for vCPU %d\n", vcpu_id);
    	}
    
    	ts_diff = timespec_diff_now(start);
    
    	pr_info("All vCPU threads joined\n");
    
    	if (use_uffd) {
    		char c;
    
    		/* Tell the user fault fd handler threads to quit */
    		for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) {
    			r = write(pipefds[vcpu_id * 2 + 1], &c, 1);
    			TEST_ASSERT(r == 1, "Unable to write to pipefd");
    
    			pthread_join(uffd_handler_threads[vcpu_id], NULL);
    		}
    	}
    
    	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",
    		perf_test_args.vcpu_args[0].pages * vcpus /
    		((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
    
    	ucall_uninit(vm);
    	kvm_vm_free(vm);
    
    	free(guest_data_prototype);
    	free(vcpu_threads);
    	if (use_uffd) {
    		free(uffd_handler_threads);
    		free(uffd_args);
    		free(pipefds);
    	}
    }
    
    struct guest_mode {
    	bool supported;
    	bool enabled;
    };
    static struct guest_mode guest_modes[NUM_VM_MODES];
    
    #define guest_mode_init(mode, supported, enabled) ({ \
    	guest_modes[mode] = (struct guest_mode){ supported, enabled }; \
    })
    
    static void help(char *name)
    {
    	int i;
    
    	puts("");
    	printf("usage: %s [-h] [-m mode] [-u] [-d uffd_delay_usec]\n"
    	       "          [-b memory] [-v vcpus]\n", name);
    	printf(" -m: specify the guest mode ID to test\n"
    	       "     (default: test all supported modes)\n"
    	       "     This option may be used multiple times.\n"
    	       "     Guest mode IDs:\n");
    	for (i = 0; i < NUM_VM_MODES; ++i) {
    		printf("         %d:    %s%s\n", i, vm_guest_mode_string(i),
    		       guest_modes[i].supported ? " (supported)" : "");
    	}
    	printf(" -u: use User Fault FD to handle vCPU page\n"
    	       "     faults.\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");
    	printf(" -v: specify the number of vCPUs to run.\n");
    	puts("");
    	exit(0);
    }
    
    int main(int argc, char *argv[])
    {
    	bool mode_selected = false;
    	uint64_t vcpu_memory_bytes = DEFAULT_GUEST_TEST_MEM_SIZE;
    	int vcpus = 1;
    	unsigned int mode;
    	int opt, i;
    	bool use_uffd = false;
    	useconds_t uffd_delay = 0;
    
    #ifdef __x86_64__
    	guest_mode_init(VM_MODE_PXXV48_4K, true, true);
    #endif
    #ifdef __aarch64__
    	guest_mode_init(VM_MODE_P40V48_4K, true, true);
    	guest_mode_init(VM_MODE_P40V48_64K, true, true);
    	{
    		unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
    
    		if (limit >= 52)
    			guest_mode_init(VM_MODE_P52V48_64K, true, true);
    		if (limit >= 48) {
    			guest_mode_init(VM_MODE_P48V48_4K, true, true);
    			guest_mode_init(VM_MODE_P48V48_64K, true, true);
    		}
    	}
    #endif
    #ifdef __s390x__
    	guest_mode_init(VM_MODE_P40V48_4K, true, true);
    #endif
    
    	while ((opt = getopt(argc, argv, "hm:ud:b:v:")) != -1) {
    		switch (opt) {
    		case 'm':
    			if (!mode_selected) {
    				for (i = 0; i < NUM_VM_MODES; ++i)
    					guest_modes[i].enabled = false;
    				mode_selected = true;
    			}
    			mode = strtoul(optarg, NULL, 10);
    			TEST_ASSERT(mode < NUM_VM_MODES,
    				    "Guest mode ID %d too big", mode);
    			guest_modes[mode].enabled = true;
    			break;
    		case 'u':
    			use_uffd = true;
    			break;
    		case 'd':
    			uffd_delay = strtoul(optarg, NULL, 0);
    			TEST_ASSERT(uffd_delay >= 0,
    				    "A negative UFFD delay is not supported.");
    			break;
    		case 'b':
    			vcpu_memory_bytes = parse_size(optarg);
    			break;
    		case 'v':
    			vcpus = atoi(optarg);
    			TEST_ASSERT(vcpus > 0,
    				    "Must have a positive number of vCPUs");
    			TEST_ASSERT(vcpus <= MAX_VCPUS,
    				    "This test does not currently support\n"
    				    "more than %d vCPUs.", MAX_VCPUS);
    			break;
    		case 'h':
    		default:
    			help(argv[0]);
    			break;
    		}
    	}
    
    	for (i = 0; i < NUM_VM_MODES; ++i) {
    		if (!guest_modes[i].enabled)
    			continue;
    		TEST_ASSERT(guest_modes[i].supported,
    			    "Guest mode ID %d (%s) not supported.",
    			    i, vm_guest_mode_string(i));
    		run_test(i, use_uffd, uffd_delay, vcpus, vcpu_memory_bytes);
    	}
    
    	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 */