Skip to content

Commit

Permalink
KVM: selftests: Factor code out of demand_paging_test
Browse files Browse the repository at this point in the history 
Much of the code in demand_paging_test can be reused by other, similar
multi-vCPU-memory-touching-perfromance-tests. Factor that common code
out for reuse.

No functional change expected.

This series was tested by running the following invocations on an Intel
Skylake machine:
dirty_log_perf_test -b 20m -i 100 -v 64
dirty_log_perf_test -b 20g -i 5 -v 4
dirty_log_perf_test -b 4g -i 5 -v 32
demand_paging_test -b 20m -v 64
demand_paging_test -b 20g -v 4
demand_paging_test -b 4g -v 32
All behaved as expected.

Signed-off-by: Ben Gardon <bgardon@google.com>
Message-Id: <20201027233733.1484855-2-bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
  • Loading branch information
Ben Gardon authored and Paolo Bonzini committed Nov 8, 2020
1 parent afdb196 commit 4b5d12b
Show file tree
Hide file tree
Showing 2 changed files with 210 additions and 181 deletions.
204 changes: 23 additions & 181 deletions tools/testing/selftests/kvm/demand_paging_test.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,18 +21,12 @@
#include <linux/bitops.h>
#include <linux/userfaultfd.h>

#include "test_util.h"
#include "kvm_util.h"
#include "perf_test_util.h"
#include "processor.h"
#include "test_util.h"

#ifdef __NR_userfaultfd

/* The memory slot index demand page */
#define TEST_MEM_SLOT_INDEX 1

/* Default guest test virtual memory offset */
#define DEFAULT_GUEST_TEST_MEM 0xc0000000

#define DEFAULT_GUEST_TEST_MEM_SIZE (1 << 30) /* 1G */

#ifdef PRINT_PER_PAGE_UPDATES
Expand All @@ -47,75 +41,14 @@
#define PER_VCPU_DEBUG(...) _no_printf(__VA_ARGS__)
#endif

#define MAX_VCPUS 512

/*
* Guest/Host shared variables. Ensure addr_gva2hva() and/or
* sync_global_to/from_guest() are used when accessing from
* the host. READ/WRITE_ONCE() should also be used with anything
* that may change.
*/
static uint64_t host_page_size;
static uint64_t guest_page_size;

static char *guest_data_prototype;

/*
* Guest physical memory offset of the testing memory slot.
* This will be set to the topmost valid physical address minus
* the test memory size.
*/
static uint64_t guest_test_phys_mem;

/*
* Guest virtual memory offset of the testing memory slot.
* Must not conflict with identity mapped test code.
*/
static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;

struct vcpu_args {
uint64_t gva;
uint64_t pages;

/* Only used by the host userspace part of the vCPU thread */
int vcpu_id;
struct kvm_vm *vm;
};

static struct vcpu_args vcpu_args[MAX_VCPUS];

/*
* Continuously write to the first 8 bytes of each page in the demand paging
* memory region.
*/
static void guest_code(uint32_t vcpu_id)
{
uint64_t gva;
uint64_t pages;
int i;

/* Make sure vCPU args data structure is not corrupt. */
GUEST_ASSERT(vcpu_args[vcpu_id].vcpu_id == vcpu_id);

gva = vcpu_args[vcpu_id].gva;
pages = vcpu_args[vcpu_id].pages;

for (i = 0; i < pages; i++) {
uint64_t addr = gva + (i * guest_page_size);

addr &= ~(host_page_size - 1);
*(uint64_t *)addr = 0x0123456789ABCDEF;
}

GUEST_SYNC(1);
}

static void *vcpu_worker(void *data)
{
int ret;
struct vcpu_args *args = (struct vcpu_args *)data;
struct kvm_vm *vm = args->vm;
int vcpu_id = args->vcpu_id;
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, end, ts_diff;

Expand All @@ -141,39 +74,6 @@ static void *vcpu_worker(void *data)
return NULL;
}

#define PAGE_SHIFT_4K 12
#define PTES_PER_4K_PT 512

static struct kvm_vm *create_vm(enum vm_guest_mode mode, int vcpus,
uint64_t vcpu_memory_bytes)
{
struct kvm_vm *vm;
uint64_t pages = DEFAULT_GUEST_PHY_PAGES;

/* 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_4K_PT;
pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /
PTES_PER_4K_PT;
pages = vm_adjust_num_guest_pages(mode, pages);

pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));

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
return vm;
}

static int handle_uffd_page_request(int uffd, uint64_t addr)
{
pid_t tid;
Expand All @@ -186,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)

copy.src = (uint64_t)guest_data_prototype;
copy.dst = addr;
copy.len = host_page_size;
copy.len = perf_test_args.host_page_size;
copy.mode = 0;

clock_gettime(CLOCK_MONOTONIC, &start);
Expand All @@ -203,7 +103,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr)
PER_PAGE_DEBUG("UFFDIO_COPY %d \t%ld ns\n", tid,
timespec_to_ns(timespec_sub(end, start)));
PER_PAGE_DEBUG("Paged in %ld bytes at 0x%lx from thread %d\n",
host_page_size, addr, tid);
perf_test_args.host_page_size, addr, tid);

return 0;
}
Expand Down Expand Up @@ -360,64 +260,21 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
struct timespec start, end, ts_diff;
int *pipefds = NULL;
struct kvm_vm *vm;
uint64_t guest_num_pages;
int vcpu_id;
int r;

vm = create_vm(mode, vcpus, vcpu_memory_bytes);

guest_page_size = vm_get_page_size(vm);

TEST_ASSERT(vcpu_memory_bytes % guest_page_size == 0,
"Guest memory size is not guest page size aligned.");

guest_num_pages = (vcpus * vcpu_memory_bytes) / guest_page_size;
guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);

/*
* If there should be more memory in the guest test region than there
* can be pages in the guest, it will definitely cause problems.
*/
TEST_ASSERT(guest_num_pages < vm_get_max_gfn(vm),
"Requested more guest memory than address space allows.\n"
" guest pages: %lx max gfn: %x vcpus: %d wss: %lx]\n",
guest_num_pages, vm_get_max_gfn(vm), vcpus,
vcpu_memory_bytes);

host_page_size = getpagesize();
TEST_ASSERT(vcpu_memory_bytes % host_page_size == 0,
"Guest memory size is not host page size aligned.");

guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
guest_page_size;
guest_test_phys_mem &= ~(host_page_size - 1);

#ifdef __s390x__
/* Align to 1M (segment size) */
guest_test_phys_mem &= ~((1 << 20) - 1);
#endif

pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);

/* Add an extra memory slot for testing demand paging */
vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
guest_test_phys_mem,
TEST_MEM_SLOT_INDEX,
guest_num_pages, 0);

/* Do mapping for the demand paging memory slot */
virt_map(vm, guest_test_virt_mem, guest_test_phys_mem, guest_num_pages, 0);

ucall_init(vm, NULL);

guest_data_prototype = malloc(host_page_size);
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, host_page_size);
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));
Expand All @@ -428,22 +285,18 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,

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;

vm_vcpu_add_default(vm, vcpu_id, guest_code);
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);
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);
/* Cache the HVA pointer of the region */
vcpu_hva = addr_gpa2hva(vm, vcpu_gpa);

if (use_uffd) {
/*
* Set up user fault fd to handle demand paging
* requests.
Expand All @@ -460,30 +313,18 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
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_memory_bytes);
vcpu_args[vcpu_id].pages = vcpu_memory_bytes / guest_page_size;
}

/* Export the shared variables to the guest */
sync_global_to_guest(vm, host_page_size);
sync_global_to_guest(vm, guest_page_size);
sync_global_to_guest(vm, vcpu_args);
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,
&vcpu_args[vcpu_id]);
&perf_test_args.vcpu_args[vcpu_id]);
}

pr_info("Started all vCPUs\n");
Expand Down Expand Up @@ -514,7 +355,8 @@ static void run_test(enum vm_guest_mode mode, bool use_uffd,
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",
guest_num_pages / ((double)ts_diff.tv_sec + (double)ts_diff.tv_nsec / 100000000.0));
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);
Expand Down
Loading

0 comments on commit 4b5d12b

Please sign in to comment.