KVM: selftests: Create a demand paging test
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
Paolo Bonzini
parent
87a802d93e
commit
025eed7b35
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@ -17,3 +17,4 @@
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/clear_dirty_log_test
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/dirty_log_test
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/kvm_create_max_vcpus
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/demand_paging_test
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@ -29,16 +29,19 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
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TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
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TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
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TEST_GEN_PROGS_x86_64 += dirty_log_test
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TEST_GEN_PROGS_x86_64 += demand_paging_test
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TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
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TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
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TEST_GEN_PROGS_aarch64 += dirty_log_test
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TEST_GEN_PROGS_aarch64 += demand_paging_test
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TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
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TEST_GEN_PROGS_s390x = s390x/memop
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TEST_GEN_PROGS_s390x += s390x/sync_regs_test
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TEST_GEN_PROGS_s390x += s390x/resets
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TEST_GEN_PROGS_s390x += dirty_log_test
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TEST_GEN_PROGS_s390x += demand_paging_test
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TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
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TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
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@ -0,0 +1,283 @@
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// SPDX-License-Identifier: GPL-2.0
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/*
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* KVM demand paging test
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* Adapted from dirty_log_test.c
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*
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* Copyright (C) 2018, Red Hat, Inc.
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* Copyright (C) 2019, Google, Inc.
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*/
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#define _GNU_SOURCE /* for program_invocation_name */
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include <time.h>
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#include <pthread.h>
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#include <linux/bitmap.h>
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#include <linux/bitops.h>
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#include "test_util.h"
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#include "kvm_util.h"
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#include "processor.h"
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#define VCPU_ID 1
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/* The memory slot index demand page */
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#define TEST_MEM_SLOT_INDEX 1
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/* Default guest test virtual memory offset */
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#define DEFAULT_GUEST_TEST_MEM 0xc0000000
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/*
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* Guest/Host shared variables. Ensure addr_gva2hva() and/or
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* sync_global_to/from_guest() are used when accessing from
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* the host. READ/WRITE_ONCE() should also be used with anything
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* that may change.
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*/
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static uint64_t host_page_size;
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static uint64_t guest_page_size;
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static uint64_t guest_num_pages;
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/*
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* Guest physical memory offset of the testing memory slot.
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* This will be set to the topmost valid physical address minus
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* the test memory size.
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*/
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static uint64_t guest_test_phys_mem;
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/*
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* Guest virtual memory offset of the testing memory slot.
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* Must not conflict with identity mapped test code.
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*/
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static uint64_t guest_test_virt_mem = DEFAULT_GUEST_TEST_MEM;
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/*
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* Continuously write to the first 8 bytes of each page in the demand paging
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* memory region.
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*/
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static void guest_code(void)
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{
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int i;
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for (i = 0; i < guest_num_pages; i++) {
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uint64_t addr = guest_test_virt_mem;
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addr += i * guest_page_size;
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addr &= ~(host_page_size - 1);
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*(uint64_t *)addr = 0x0123456789ABCDEF;
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}
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GUEST_SYNC(1);
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}
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/* Points to the test VM memory region on which we are doing demand paging */
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static void *host_test_mem;
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static uint64_t host_num_pages;
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static void *vcpu_worker(void *data)
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{
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int ret;
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struct kvm_vm *vm = data;
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struct kvm_run *run;
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run = vcpu_state(vm, VCPU_ID);
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/* Let the guest access its memory */
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ret = _vcpu_run(vm, VCPU_ID);
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TEST_ASSERT(ret == 0, "vcpu_run failed: %d\n", ret);
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if (get_ucall(vm, VCPU_ID, NULL) != UCALL_SYNC) {
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TEST_ASSERT(false,
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"Invalid guest sync status: exit_reason=%s\n",
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exit_reason_str(run->exit_reason));
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}
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return NULL;
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}
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static struct kvm_vm *create_vm(enum vm_guest_mode mode, uint32_t vcpuid,
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uint64_t extra_mem_pages, void *guest_code)
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{
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struct kvm_vm *vm;
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uint64_t extra_pg_pages = extra_mem_pages / 512 * 2;
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vm = _vm_create(mode, DEFAULT_GUEST_PHY_PAGES + extra_pg_pages, O_RDWR);
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kvm_vm_elf_load(vm, program_invocation_name, 0, 0);
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#ifdef __x86_64__
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vm_create_irqchip(vm);
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#endif
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vm_vcpu_add_default(vm, vcpuid, guest_code);
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return vm;
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}
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#define GUEST_MEM_SHIFT 30 /* 1G */
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#define PAGE_SHIFT_4K 12
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static void run_test(enum vm_guest_mode mode)
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{
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pthread_t vcpu_thread;
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struct kvm_vm *vm;
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/*
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* We reserve page table for 2 times of extra dirty mem which
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* will definitely cover the original (1G+) test range. Here
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* we do the calculation with 4K page size which is the
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* smallest so the page number will be enough for all archs
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* (e.g., 64K page size guest will need even less memory for
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* page tables).
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*/
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vm = create_vm(mode, VCPU_ID,
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2ul << (GUEST_MEM_SHIFT - PAGE_SHIFT_4K),
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guest_code);
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guest_page_size = vm_get_page_size(vm);
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/*
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* A little more than 1G of guest page sized pages. Cover the
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* case where the size is not aligned to 64 pages.
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*/
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guest_num_pages = (1ul << (GUEST_MEM_SHIFT -
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vm_get_page_shift(vm))) + 16;
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#ifdef __s390x__
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/* Round up to multiple of 1M (segment size) */
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guest_num_pages = (guest_num_pages + 0xff) & ~0xffUL;
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#endif
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host_page_size = getpagesize();
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host_num_pages = (guest_num_pages * guest_page_size) / host_page_size +
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!!((guest_num_pages * guest_page_size) %
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host_page_size);
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guest_test_phys_mem = (vm_get_max_gfn(vm) - guest_num_pages) *
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guest_page_size;
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guest_test_phys_mem &= ~(host_page_size - 1);
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#ifdef __s390x__
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/* Align to 1M (segment size) */
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guest_test_phys_mem &= ~((1 << 20) - 1);
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#endif
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DEBUG("guest physical test memory offset: 0x%lx\n",
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guest_test_phys_mem);
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/* Add an extra memory slot for testing demand paging */
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vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,
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guest_test_phys_mem,
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TEST_MEM_SLOT_INDEX,
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guest_num_pages, 0);
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/* Do mapping for the demand paging memory slot */
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virt_map(vm, guest_test_virt_mem, guest_test_phys_mem,
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guest_num_pages * guest_page_size, 0);
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/* Cache the HVA pointer of the region */
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host_test_mem = addr_gpa2hva(vm, (vm_paddr_t)guest_test_phys_mem);
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#ifdef __x86_64__
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vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
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#endif
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#ifdef __aarch64__
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ucall_init(vm, NULL);
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#endif
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/* Export the shared variables to the guest */
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sync_global_to_guest(vm, host_page_size);
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sync_global_to_guest(vm, guest_page_size);
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sync_global_to_guest(vm, guest_test_virt_mem);
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sync_global_to_guest(vm, guest_num_pages);
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pthread_create(&vcpu_thread, NULL, vcpu_worker, vm);
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/* Wait for the vcpu thread to quit */
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pthread_join(vcpu_thread, NULL);
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ucall_uninit(vm);
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kvm_vm_free(vm);
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}
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struct guest_mode {
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bool supported;
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bool enabled;
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};
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static struct guest_mode guest_modes[NUM_VM_MODES];
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#define guest_mode_init(mode, supported, enabled) ({ \
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guest_modes[mode] = (struct guest_mode){ supported, enabled }; \
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})
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static void help(char *name)
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{
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int i;
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puts("");
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printf("usage: %s [-h] [-m mode]\n", name);
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printf(" -m: specify the guest mode ID to test\n"
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" (default: test all supported modes)\n"
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" This option may be used multiple times.\n"
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" Guest mode IDs:\n");
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for (i = 0; i < NUM_VM_MODES; ++i) {
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printf(" %d: %s%s\n", i, vm_guest_mode_string(i),
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guest_modes[i].supported ? " (supported)" : "");
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}
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puts("");
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exit(0);
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}
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int main(int argc, char *argv[])
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{
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bool mode_selected = false;
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unsigned int mode;
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int opt, i;
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#ifdef __x86_64__
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guest_mode_init(VM_MODE_PXXV48_4K, true, true);
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#endif
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#ifdef __aarch64__
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guest_mode_init(VM_MODE_P40V48_4K, true, true);
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guest_mode_init(VM_MODE_P40V48_64K, true, true);
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{
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unsigned int limit = kvm_check_cap(KVM_CAP_ARM_VM_IPA_SIZE);
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if (limit >= 52)
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guest_mode_init(VM_MODE_P52V48_64K, true, true);
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if (limit >= 48) {
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guest_mode_init(VM_MODE_P48V48_4K, true, true);
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guest_mode_init(VM_MODE_P48V48_64K, true, true);
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}
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}
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#endif
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#ifdef __s390x__
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guest_mode_init(VM_MODE_P40V48_4K, true, true);
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#endif
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while ((opt = getopt(argc, argv, "hm:")) != -1) {
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switch (opt) {
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case 'm':
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if (!mode_selected) {
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for (i = 0; i < NUM_VM_MODES; ++i)
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guest_modes[i].enabled = false;
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mode_selected = true;
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}
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mode = strtoul(optarg, NULL, 10);
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TEST_ASSERT(mode < NUM_VM_MODES,
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"Guest mode ID %d too big", mode);
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guest_modes[mode].enabled = true;
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break;
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case 'h':
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default:
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help(argv[0]);
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break;
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}
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}
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for (i = 0; i < NUM_VM_MODES; ++i) {
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if (!guest_modes[i].enabled)
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continue;
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TEST_ASSERT(guest_modes[i].supported,
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"Guest mode ID %d (%s) not supported.",
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i, vm_guest_mode_string(i));
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run_test(i);
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}
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return 0;
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}
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