Most VMs have multiple vCPUs, the concurrent execution of which has a substantial impact on demand paging performance. Add an option to create multiple vCPUs to each access disjoint regions of memory.
Signed-off-by: Ben Gardon bgardon@google.com --- .../selftests/kvm/demand_paging_test.c | 187 ++++++++++++------ 1 file changed, 127 insertions(+), 60 deletions(-)
diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c index 8fd46e99d9e30..f8afc0683c346 100644 --- a/tools/testing/selftests/kvm/demand_paging_test.c +++ b/tools/testing/selftests/kvm/demand_paging_test.c @@ -24,8 +24,6 @@ #include "kvm_util.h" #include "processor.h"
-#define VCPU_ID 1 - /* The memory slot index demand page */ #define TEST_MEM_SLOT_INDEX 1
@@ -36,6 +34,12 @@
#define __NR_userfaultfd 323
+#ifdef PRINT_PER_VCPU_UPDATES +#define PER_VCPU_DEBUG(...) DEBUG(__VA_ARGS__) +#else +#define PER_VCPU_DEBUG(...) +#endif + /* * Guest/Host shared variables. Ensure addr_gva2hva() and/or * sync_global_to/from_guest() are used when accessing from @@ -78,10 +82,6 @@ static void guest_code(uint64_t gva, uint64_t pages) GUEST_SYNC(1); }
-/* Points to the test VM memory region on which we are doing demand paging */ -static void *host_test_mem; -static uint64_t host_num_pages; - struct vcpu_thread_args { uint64_t gva; uint64_t pages; @@ -115,18 +115,32 @@ static void *vcpu_worker(void *data) return NULL; }
-static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid, - uint64_t extra_mem_pages, void *guest_code) +#define PAGE_SHIFT_4K 12 +#define PTES_PER_PT 512 + +static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus, + uint64_t vcpu_wss) { struct kvm_vm *vm; - uint64_t extra_pg_pages = extra_mem_pages / 512 * 2; + uint64_t pages = DEFAULT_GUEST_PHY_PAGES;
- vm = _vm_create(mode, DEFAULT_GUEST_PHY_PAGES + extra_pg_pages, O_RDWR); + /* Account for a few pages per-vCPU for stacks */ + pages += DEFAULT_STACK_PGS * vcpus; + + /* + * Reserve twice the ammount of memory needed to map the test region and + * the page table / stacks region, at 4k, for page tables. Do the + * calculation with 4K page size: the smallest of all archs. (e.g., 64K + * page size guest will need even less memory for page tables). + */ + pages += (2 * pages) / PTES_PER_PT; + pages += ((2 * vcpus * vcpu_wss) >> PAGE_SHIFT_4K) / PTES_PER_PT; + + vm = _vm_create(mode, pages, O_RDWR); kvm_vm_elf_load(vm, program_invocation_name, 0, 0); #ifdef __x86_64__ vm_create_irqchip(vm); #endif - vm_vcpu_add_default(vm, vcpuid, guest_code); return vm; }
@@ -224,15 +238,13 @@ static void *uffd_handler_thread_fn(void *arg) }
static int setup_demand_paging(struct kvm_vm *vm, - pthread_t *uffd_handler_thread) + pthread_t *uffd_handler_thread, + struct uffd_handler_args *uffd_args, + void *hva, uint64_t len) { int uffd; struct uffdio_api uffdio_api; struct uffdio_register uffdio_register; - struct uffd_handler_args uffd_args; - - guest_data_prototype = malloc(host_page_size); - memset(guest_data_prototype, 0xAB, host_page_size);
uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); if (uffd == -1) { @@ -247,8 +259,8 @@ static int setup_demand_paging(struct kvm_vm *vm, return -1; }
- uffdio_register.range.start = (uint64_t)host_test_mem; - uffdio_register.range.len = host_num_pages * host_page_size; + 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) { DEBUG("ioctl uffdio_register failed\n"); @@ -261,40 +273,35 @@ static int setup_demand_paging(struct kvm_vm *vm, return -1; }
- uffd_args.uffd = uffd; + uffd_args->uffd = uffd; pthread_create(uffd_handler_thread, NULL, uffd_handler_thread_fn, - &uffd_args); + uffd_args); + + PER_VCPU_DEBUG("Created uffd thread for HVA range [%p, %p)\n", + hva, hva + len);
return 0; }
-#define PAGE_SHIFT_4K 12 - -static void run_test(enum vm_guest_mode mode, uint64_t vcpu_wss) +static void run_test(enum vm_guest_mode mode, int vcpus, uint64_t vcpu_wss) { - pthread_t vcpu_thread; - pthread_t uffd_handler_thread; + pthread_t *vcpu_threads; + pthread_t *uffd_handler_threads; + struct uffd_handler_args *uffd_args; struct kvm_vm *vm; - struct vcpu_thread_args vcpu_args; + struct vcpu_thread_args *vcpu_args; uint64_t guest_num_pages; + int vcpu_id; int r;
- /* - * We reserve page table for twice the ammount of memory we intend - * to use in the test region for demand paging. Here we do the - * calculation with 4K page size which is the smallest so the page - * number will be enough for all archs. (e.g., 64K page size guest - * will need even less memory for page tables). - */ - vm = create_vm(mode, VCPU_ID, (2 * vcpu_wss) >> PAGE_SHIFT_4K, - guest_code); + vm = create_vm(mode, vcpus, vcpu_wss);
guest_page_size = vm_get_page_size(vm);
TEST_ASSERT(vcpu_wss % guest_page_size == 0, "Guest memory size is not guest page size aligned.");
- guest_num_pages = vcpu_wss / guest_page_size; + guest_num_pages = (vcpus * vcpu_wss) / guest_page_size;
#ifdef __s390x__ /* Round up to multiple of 1M (segment size) */ @@ -306,13 +313,12 @@ static void run_test(enum vm_guest_mode mode, uint64_t vcpu_wss) */ TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm), "Requested more guest memory than address space allows.\n" - " guest pages: %lx max gfn: %lx\n", - guest_num_pages, vm_get_max_gfn(vm)); + " guest pages: %lx max gfn: %lx vcpus: %d wss: %lx]\n", + guest_num_pages, vm_get_max_gfn(vm), vcpus, vcpu_wss);
host_page_size = getpagesize(); TEST_ASSERT(vcpu_wss % host_page_size == 0, "Guest memory size is not host page size aligned."); - host_num_pages = vcpu_wss / host_page_size;
guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) * guest_page_size; @@ -337,18 +343,8 @@ static void run_test(enum vm_guest_mode mode, uint64_t vcpu_wss) virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages * guest_page_size, 0);
- /* Cache the HVA pointer of the region */ - host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem); - - /* Set up user fault fd to handle demand paging requests. */ quit_uffd_thread = false; - r = setup_demand_paging(vm, &uffd_handler_thread); - if (r < 0) - exit(-r);
-#ifdef __x86_64__ - vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid()); -#endif #ifdef __aarch64__ ucall_init(vm, NULL); #endif @@ -357,21 +353,83 @@ static void run_test(enum vm_guest_mode mode, uint64_t vcpu_wss) sync_global_to_guest(vm, host_page_size); sync_global_to_guest(vm, guest_page_size);
- vcpu_args.vm = vm; - vcpu_args.vcpu_id = VCPU_ID; - vcpu_args.gva = guest_test_virt_mem; - vcpu_args.pages = guest_num_pages; - pthread_create(&vcpu_thread, NULL, vcpu_worker, &vcpu_args); + guest_data_prototype = malloc(host_page_size); + TEST_ASSERT(guest_data_prototype, "Memory allocation failed"); + memset(guest_data_prototype, 0xAB, host_page_size); + + vcpu_threads = malloc(vcpus * sizeof(*vcpu_threads)); + TEST_ASSERT(vcpu_threads, "Memory allocation failed"); + + 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"); + + vcpu_args = malloc(vcpus * sizeof(*vcpu_args)); + TEST_ASSERT(vcpu_args, "Memory allocation failed"); + + for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) { + vm_paddr_t vcpu_gpa; + void *vcpu_hva; + + vm_vcpu_add_default(vm, vcpu_id, guest_code); + + vcpu_gpa = guest_test_phys_mem + (vcpu_id * vcpu_wss); + PER_VCPU_DEBUG("Added VCPU %d with test mem gpa [%lx, %lx)\n", + vcpu_id, vcpu_gpa, vcpu_gpa + vcpu_wss); + + /* 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 = setup_demand_paging(vm, &uffd_handler_threads[vcpu_id], + &uffd_args[vcpu_id], vcpu_hva, + vcpu_wss); + if (r < 0) + exit(-r); + +#ifdef __x86_64__ + vcpu_set_cpuid(vm, vcpu_id, kvm_get_supported_cpuid()); +#endif + + vcpu_args[vcpu_id].vm = vm; + vcpu_args[vcpu_id].vcpu_id = vcpu_id; + vcpu_args[vcpu_id].gva = guest_test_virt_mem + + (vcpu_id * vcpu_wss); + vcpu_args[vcpu_id].pages = vcpu_wss / guest_page_size; + } + + DEBUG("Finished creating vCPUs and starting uffd threads\n"); + + for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) { + pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker, + &vcpu_args[vcpu_id]); + } + + DEBUG("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); + }
- /* Wait for the vcpu thread to quit */ - pthread_join(vcpu_thread, NULL); + DEBUG("All vCPU threads joined\n");
/* Tell the user fault fd handler thread to quit */ quit_uffd_thread = true; - pthread_join(uffd_handler_thread, NULL); + for (vcpu_id = 0; vcpu_id < vcpus; vcpu_id++) + pthread_join(uffd_handler_threads[vcpu_id], NULL);
ucall_uninit(vm); kvm_vm_free(vm); + + free(guest_data_prototype); + free(vcpu_threads); + free(uffd_handler_threads); + free(uffd_args); + free(vcpu_args); }
struct vm_guest_mode_params { @@ -391,7 +449,8 @@ static void help(char *name) int i;
puts(""); - printf("usage: %s [-h] [-m mode] [-b bytes test memory]\n", name); + printf("usage: %s [-h] [-m mode] [-b bytes test 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" @@ -401,6 +460,7 @@ static void help(char *name) vm_guest_mode_params[i].supported ? " (supported)" : ""); } printf(" -b: specify the working set size, in bytes for each vCPU.\n"); + printf(" -v: specify the number of vCPUs to run.\n"); puts(""); exit(0); } @@ -409,6 +469,7 @@ int main(int argc, char *argv[]) { bool mode_selected = false; uint64_t vcpu_wss = DEFAULT_GUEST_TEST_MEM_SIZE; + int vcpus = 1; unsigned int mode; int opt, i; #ifdef __aarch64__ @@ -434,7 +495,7 @@ int main(int argc, char *argv[]) vm_guest_mode_params_init(VM_MODE_P40V48_4K, true, true); #endif
- while ((opt = getopt(argc, argv, "hm:b:")) != -1) { + while ((opt = getopt(argc, argv, "hm:b:v:")) != -1) { switch (opt) { case 'm': if (!mode_selected) { @@ -449,6 +510,12 @@ int main(int argc, char *argv[]) break; case 'b': vcpu_wss = strtoull(optarg, NULL, 0); + break; + case 'v': + vcpus = atoi(optarg); + TEST_ASSERT(vcpus > 0, + "Must have a positive number of vCPUs"); + break; case 'h': default: help(argv[0]); @@ -462,7 +529,7 @@ int main(int argc, char *argv[]) TEST_ASSERT(vm_guest_mode_params[i].supported, "Guest mode ID %d (%s) not supported.", i, vm_guest_mode_string(i)); - run_test(i, vcpu_wss); + run_test(i, vcpus, vcpu_wss); }
return 0;