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KVM: selftests: Create a demand paging test

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While userfaultfd, KVM's demand paging implementation, is not specific
to KVM, having a benchmark for its performance will be useful for
guiding performance improvements to KVM. As a first step towards creating
a userfaultfd demand paging test, create a simple memory access test,
based on dirty_log_test.

Reviewed-by: Oliver Upton <oupton@google.com>
Signed-off-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Ben Gardon 2020-01-23 10:04:27 -08:00 committed by Paolo Bonzini
parent 87a802d93e
commit 025eed7b35
3 changed files with 287 additions and 0 deletions
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1
tools/testing/selftests/kvm/.gitignore vendored
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@ -17,3 +17,4 @@
/clear_dirty_log_test
/dirty_log_test
/kvm_create_max_vcpus
/demand_paging_test

3
tools/testing/selftests/kvm/Makefile
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@ -29,16 +29,19 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
TEST_GEN_PROGS_x86_64 += demand_paging_test
TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
TEST_GEN_PROGS_aarch64 += dirty_log_test
TEST_GEN_PROGS_aarch64 += demand_paging_test
TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
TEST_GEN_PROGS_s390x = s390x/memop
TEST_GEN_PROGS_s390x += s390x/sync_regs_test
TEST_GEN_PROGS_s390x += s390x/resets
TEST_GEN_PROGS_s390x += dirty_log_test
TEST_GEN_PROGS_s390x += demand_paging_test
TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))

283
tools/testing/selftests/kvm/demand_paging_test.c Normal file
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@ -0,0 +1,283 @@
// 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 <unistd.h>
#include <time.h>
#include <pthread.h>
#include <linux/bitmap.h>
#include <linux/bitops.h>
#include "test_util.h"
#include "kvm_util.h"
#include "processor.h"
#define VCPU_ID 1
/* The memory slot index demand page */
#define TEST_MEM_SLOT_INDEX 1
/* Default guest test virtual memory offset */
#define DEFAULT_GUEST_TEST_MEM 0xc0000000
/*
* 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 uint64_t guest_num_pages;
/*
* 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;
/*
* Continuously write to the first 8 bytes of each page in the demand paging
* memory region.
*/
static void guest_code(void)
{
int i;
for (i = 0; i < guest_num_pages; i++) {
uint64_t addr = guest_test_virt_mem;
addr += i * guest_page_size;
addr &= ~(host_page_size - 1);
*(uint64_t *)addr = 0x0123456789ABCDEF;
}
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;
static void *vcpu_worker(void *data)
{
int ret;
struct kvm_vm *vm = data;
struct kvm_run *run;
run = vcpu_state(vm, VCPU_ID);
/* 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));
}
return NULL;
}
static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid,
uint64_t extra_mem_pages, void *guest_code)
{
struct kvm_vm *vm;
uint64_t extra_pg_pages = extra_mem_pages / 512 * 2;
vm = _vm_create(mode, DEFAULT_GUEST_PHY_PAGES + extra_pg_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;
}
#define GUEST_MEM_SHIFT 30 /* 1G */
#define PAGE_SHIFT_4K 12
static void run_test(enum vm_guest_mode mode)
{
pthread_t vcpu_thread;
struct kvm_vm *vm;
/*
* We reserve page table for 2 times of extra dirty mem which
* will definitely cover the original (1G+) test range. 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,
2ul << (GUEST_MEM_SHIFT - PAGE_SHIFT_4K),
guest_code);
guest_page_size = vm_get_page_size(vm);
/*
* A little more than 1G of guest page sized pages. Cover the
* case where the size is not aligned to 64 pages.
*/
guest_num_pages = (1ul << (GUEST_MEM_SHIFT -
vm_get_page_shift(vm))) + 16;
#ifdef __s390x__
/* Round up to multiple of 1M (segment size) */
guest_num_pages = (guest_num_pages + 0xff) & ~0xffUL;
#endif
host_page_size = getpagesize();
host_num_pages = (guest_num_pages * guest_page_size) / host_page_size +
!!((guest_num_pages * guest_page_size) %
host_page_size);
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
DEBUG("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 * guest_page_size, 0);
/* Cache the HVA pointer of the region */
host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
#ifdef __x86_64__
vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
#endif
#ifdef __aarch64__
ucall_init(vm, NULL);
#endif
/* 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, guest_test_virt_mem);
sync_global_to_guest(vm, guest_num_pages);
pthread_create(&vcpu_thread, NULL, vcpu_worker, vm);
/* Wait for the vcpu thread to quit */
pthread_join(vcpu_thread, NULL);
ucall_uninit(vm);
kvm_vm_free(vm);
}
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]\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)" : "");
}
puts("");
exit(0);
}
int main(int argc, char *argv[])
{
bool mode_selected = false;
unsigned int mode;
int opt, i;
#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:")) != -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 '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);
}
return 0;
}