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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * Test shared zeropage handling (with/without storage keys)4 *5 * Copyright (C) 2024, Red Hat, Inc.6 */7#include <sys/mman.h>8 9#include <linux/fs.h>10 11#include "test_util.h"12#include "kvm_util.h"13#include "kselftest.h"14#include "ucall_common.h"15 16static void set_storage_key(void *addr, uint8_t skey)17{18 asm volatile("sske %0,%1" : : "d" (skey), "a" (addr));19}20 21static void guest_code(void)22{23 /* Issue some storage key instruction. */24 set_storage_key((void *)0, 0x98);25 GUEST_DONE();26}27 28/*29 * Returns 1 if the shared zeropage is mapped, 0 if something else is mapped.30 * Returns < 0 on error or if nothing is mapped.31 */32static int maps_shared_zeropage(int pagemap_fd, void *addr)33{34 struct page_region region;35 struct pm_scan_arg arg = {36 .start = (uintptr_t)addr,37 .end = (uintptr_t)addr + 4096,38 .vec = (uintptr_t)®ion,39 .vec_len = 1,40 .size = sizeof(struct pm_scan_arg),41 .category_mask = PAGE_IS_PFNZERO,42 .category_anyof_mask = PAGE_IS_PRESENT,43 .return_mask = PAGE_IS_PFNZERO,44 };45 return ioctl(pagemap_fd, PAGEMAP_SCAN, &arg);46}47 48int main(int argc, char *argv[])49{50 char *mem, *page0, *page1, *page2, tmp;51 const size_t pagesize = getpagesize();52 struct kvm_vcpu *vcpu;53 struct kvm_vm *vm;54 struct ucall uc;55 int pagemap_fd;56 57 ksft_print_header();58 ksft_set_plan(3);59 60 /*61 * We'll use memory that is not mapped into the VM for simplicity.62 * Shared zeropages are enabled/disabled per-process.63 */64 mem = mmap(0, 3 * pagesize, PROT_READ, MAP_PRIVATE | MAP_ANON, -1, 0);65 TEST_ASSERT(mem != MAP_FAILED, "mmap() failed");66 67 /* Disable THP. Ignore errors on older kernels. */68 madvise(mem, 3 * pagesize, MADV_NOHUGEPAGE);69 70 page0 = mem;71 page1 = page0 + pagesize;72 page2 = page1 + pagesize;73 74 /* Can we even detect shared zeropages? */75 pagemap_fd = open("/proc/self/pagemap", O_RDONLY);76 TEST_REQUIRE(pagemap_fd >= 0);77 78 tmp = *page0;79 asm volatile("" : "+r" (tmp));80 TEST_REQUIRE(maps_shared_zeropage(pagemap_fd, page0) == 1);81 82 vm = vm_create_with_one_vcpu(&vcpu, guest_code);83 84 /* Verify that we get the shared zeropage after VM creation. */85 tmp = *page1;86 asm volatile("" : "+r" (tmp));87 ksft_test_result(maps_shared_zeropage(pagemap_fd, page1) == 1,88 "Shared zeropages should be enabled\n");89 90 /*91 * Let our VM execute a storage key instruction that should92 * unshare all shared zeropages.93 */94 vcpu_run(vcpu);95 get_ucall(vcpu, &uc);96 TEST_ASSERT_EQ(uc.cmd, UCALL_DONE);97 98 /* Verify that we don't have a shared zeropage anymore. */99 ksft_test_result(!maps_shared_zeropage(pagemap_fd, page1),100 "Shared zeropage should be gone\n");101 102 /* Verify that we don't get any new shared zeropages. */103 tmp = *page2;104 asm volatile("" : "+r" (tmp));105 ksft_test_result(!maps_shared_zeropage(pagemap_fd, page2),106 "Shared zeropages should be disabled\n");107 108 kvm_vm_free(vm);109 110 ksft_finished();111}112